Programme of self-reactive innate-like T cell-mediated cancer immunity.

Cellular transformation induces phenotypically diverse populations of tumour-infiltrating T cells1-5, and immune checkpoint blockade therapies preferentially target T cells that recognize cancer cell neoantigens6,7. Yet, how other classes of tumour-infiltrating T cells contribute to cancer immunosurveillance remains elusive. Here, in a survey of T cells in mouse and human malignancies, we identified a population of αß T cell receptor (TCR)-positive FCER1G-expressing innate-like T cells with high cytotoxic potential8 (ILTCKs). These cells were broadly reactive to unmutated self-antigens, arose from distinct thymic progenitors following early encounter with cognate antigens, and were continuously replenished by thymic progenitors during tumour progression. Notably, expansion and effector differentiation of intratumoural ILTCKs depended on interleukin-15 (IL-15) expression in cancer cells, and inducible activation of IL-15 signalling in adoptively transferred ILTCK progenitors suppressed tumour growth. Thus, the antigen receptor self-reactivity, unique ontogeny, and distinct cancer cell-sensing mechanism distinguish ILTCKs from conventional cytotoxic T cells, and define a new class of tumour-elicited immune response.

Preoperative Treatment of Locally Advanced Rectal Cancer.

BACKGROUND: Pelvic radiation plus sensitizing chemotherapy with a fluoropyrimidine (chemoradiotherapy) before surgery is standard care for locally advanced rectal cancer in North America. Whether neoadjuvant chemotherapy with fluorouracil, leucovorin, and oxaliplatin (FOLFOX) can be used in lieu of chemoradiotherapy is uncertain. METHODS: We conducted a multicenter, unblinded, noninferiority, randomized trial of neoadjuvant FOLFOX (with chemoradiotherapy given only if the primary tumor decreased in size by <20% or if FOLFOX was discontinued because of side effects) as compared with chemoradiotherapy. Adults with rectal cancer that had been clinically staged as T2 node-positive, T3 node-negative, or T3 node-positive who were candidates for sphincter-sparing surgery were eligible to participate. The primary end point was disease-free survival. Noninferiority would be claimed if the upper limit of the two-sided 90.2% confidence interval of the hazard ratio for disease recurrence or death did not exceed 1.29. Secondary end points included overall survival, local recurrence (in a time-to-event analysis), complete pathological resection, complete response, and toxic effects. RESULTS: From June 2012 through December 2018, a total of 1194 patients underwent randomization and 1128 started treatment; among those who started treatment, 585 were in the FOLFOX group and 543 in the chemoradiotherapy group. At a median follow-up of 58 months, FOLFOX was noninferior to chemoradiotherapy for disease-free survival (hazard ratio for disease recurrence or death, 0.92; 90.2% confidence interval [CI], 0.74 to 1.14; P = 0.005 for noninferiority). Five-year disease-free survival was 80.8% (95% CI, 77.9 to 83.7) in the FOLFOX group and 78.6% (95% CI, 75.4 to 81.8) in the chemoradiotherapy group. The groups were similar with respect to overall survival (hazard ratio for death, 1.04; 95% CI, 0.74 to 1.44) and local recurrence (hazard ratio, 1.18; 95% CI, 0.44 to 3.16). In the FOLFOX group, 53 patients (9.1%) received preoperative chemoradiotherapy and 8 (1.4%) received postoperative chemoradiotherapy. CONCLUSIONS: In patients with locally advanced rectal cancer who were eligible for sphincter-sparing surgery, preoperative FOLFOX was noninferior to preoperative chemoradiotherapy with respect to disease-free survival. (Funded by the National Cancer Institute; PROSPECT ClinicalTrials.gov number, NCT01515787.).

PD-1 Blockade in Mismatch Repair-Deficient, Locally Advanced Rectal Cancer.

BACKGROUND: Neoadjuvant chemotherapy and radiation followed by surgical resection of the rectum is a standard treatment for locally advanced rectal cancer. A subset of rectal cancer is caused by a deficiency in mismatch repair. Because mismatch repair-deficient colorectal cancer is responsive to programmed death 1 (PD-1) blockade in the context of metastatic disease, it was hypothesized that checkpoint blockade could be effective in patients with mismatch repair-deficient, locally advanced rectal cancer. METHODS: We initiated a prospective phase 2 study in which single-agent dostarlimab, an anti-PD-1 monoclonal antibody, was administered every 3 weeks for 6 months in patients with mismatch repair-deficient stage II or III rectal adenocarcinoma. This treatment was to be followed by standard chemoradiotherapy and surgery. Patients who had a clinical complete response after completion of dostarlimab therapy would proceed without chemoradiotherapy and surgery. The primary end points are sustained clinical complete response 12 months after completion of dostarlimab therapy or pathological complete response after completion of dostarlimab therapy with or without chemoradiotherapy and overall response to neoadjuvant dostarlimab therapy with or without chemoradiotherapy. RESULTS: A total of 12 patients have completed treatment with dostarlimab and have undergone at least 6 months of follow-up. All 12 patients (100%; 95% confidence interval, 74 to 100) had a clinical complete response, with no evidence of tumor on magnetic resonance imaging, 18F-fluorodeoxyglucose-positron-emission tomography, endoscopic evaluation, digital rectal examination, or biopsy. At the time of this report, no patients had received chemoradiotherapy or undergone surgery, and no cases of progression or recurrence had been reported during follow-up (range, 6 to 25 months). No adverse events of grade 3 or higher have been reported. CONCLUSIONS: Mismatch repair-deficient, locally advanced rectal cancer was highly sensitive to single-agent PD-1 blockade. Longer follow-up is needed to assess the duration of response. (Funded by the Simon and Eve Colin Foundation and others; ClinicalTrials.gov number, NCT04165772.).

Association of Lateral Pelvic Lymph Nodes with Disease Recurrence and Organ Preservation in Patients with Distal Rectal Adenocarcinoma Treated with Total Neoadjuvant Therapy.

OBJECTIVE: Assess the significance of enlarged lateral lymph nodes (LLN) for disease recurrence, metastasis, and organ preservation in patients with rectal cancer. BACKGROUND: Optimal treatment of rectal adenocarcinoma involving LLN is subject to debate. METHODS: A post hoc analysis of the OPRA trial, a multicenter study of patients with rectal cancer treated with total neoadjuvant therapy (TNT) followed by total mesorectal excision or watch-and-wait management. We analyzed the association of visible LLN (LLN+), LLN≥7 mm (short axis) on baseline MRI, and LLN≥4 mm on restaging MRI with recurrence, metastasis, and rectum preservation. RESULTS: At baseline, 57 out of 324 (18%) patients had LLN+. In 30 (53%) of 57 patients with LLN+ on baseline MRI, the LLN disappeared after TNT. Disease recurrence in LLN was rare (3.5% of patients with LLN+ and 0.4% of patients with LLN-). All patients with recurrence in LLN also had distant metastasis. The rate of organ preservation was significantly lower in patients with LLN≥4 mm on restaging MRI (P=0.013). We found no significant differences in rates of local recurrence or metastasis between patients with LLN+ vs. LLN- and in patients with LLN≥7 vs.<7 mm on baseline MRI. LLN dissection was performed in 3 patients; 2 of them died of distant metastasis. CONCLUSIONS: LLN involvement is not associated with disease recurrence or metastasis, but persistence of LLN≥4 mm after TNT is negatively associated with rectum preservation in patients with locally advanced rectal cancer treated with TNT. Dissection of lateral nodes likely benefits few patients.

Assessing Endoscopic Response in Locally Advanced Rectal Cancer Treated with Total Neoadjuvant Therapy: Development and Validation of a Highly Accurate Convolutional Neural Network.

BACKGROUND: Rectal tumors display varying degrees of response to total neoadjuvant therapy (TNT). We evaluated the performance of a convolutional neural network (CNN) in interpreting endoscopic images of either a non-complete response to TNT or local regrowth during watch-and-wait surveillance. METHODS: Endoscopic images from stage II/III rectal cancers treated with TNT from 2012 to 2020 at a single institution were retrospectively reviewed. Images were labelled as Tumor or No Tumor based on endoscopy timing (before, during, or after treatment) and the tumor's endoluminal response. A CNN was trained using ResNet-50 architecture. The area under the curve (AUC) was analyzed during training and for two test sets. The main test set included images of tumors treated with TNT. The other contained images of local regrowth. The model's performance was compared to sixteen surgeons and surgical trainees who evaluated 119 images for evidence of tumor. Fleiss' kappa was calculated by respondent experience level. RESULTS: A total of 2717 images from 288 patients were included; 1407 (51.8%) contained tumor. The AUC was 0.99, 0.98, and 0.92 for training, main test, and local regrowth test sets. The model performed on par with surgeons of all experience levels for the main test set. Interobserver agreement was good ( k = 0.71-0.81). All groups outperformed the model in identifying tumor from images of local regrowth. Interobserver agreement was fair to moderate ( k = 0.24-0.52). CONCLUSIONS: A highly accurate CNN matched the performance of colorectal surgeons in identifying a noncomplete response to TNT. However, the model demonstrated suboptimal accuracy when analyzing images of local regrowth.

Validation of a Clinical Calculator Predicting Freedom From Colon Cancer Recurrence After Surgery on the Basis of Molecular and Clinical Variables.

BACKGROUND: The Memorial Sloan Kettering clinical calculator for estimating the likelihood of freedom from colon cancer recurrence on the basis of clinical and molecular variables was developed at a time when testing for microsatellite instability was performed selectively, based on patient age, family history, and histologic features. Microsatellite stability was assumed if no testing was done. OBJECTIVE: This study aimed to validate the calculator in a cohort of patients who had all been tested for microsatellite instability. DESIGN: Retrospective cohort analysis. SETTINGS: Comprehensive cancer center. PATIENTS: This study included consecutive patients who underwent curative resection for stage I, II, or III colon cancer between 2017 and 2019. INTERVENTION: Universal testing of mircrosatellite phenotype in all cases. MAIN OUTCOME MEASURES: The calculator's predictive accuracy was assessed using the concordance index and a calibration plot of predicted versus actual freedom from recurrence at 3 years after surgery. For a secondary sensitivity analysis, the presence of a tumor deposit(s) (disease category N1c) was considered equivalent to one positive lymph node (category N1a). RESULTS: With a median follow-up of 32 months among survivors, the concordance index for the 745 patients in the cohort was 0.748 (95% CI, 0.693-0.801), and a plot of predicted versus observed recurrences approached the 45° diagonal, indicating good discrimination and calibration. In the secondary sensitivity analysis for tumor deposits, the concordance index was 0.755 (95% CI, 0.700-0.806). LIMITATIONS: This study was limited by its retrospective, single-institution design. CONCLUSIONS: These results, based on inclusion of actual rather than imputed microsatellite stability status and presence of tumor deposits, confirm the predictive accuracy and reliability of the calculator. See Video Abstract . VALIDACIN DE UNA CALCULADORA CLNICA QUE PREDICE LA AUSENCIA DE RECURRENCIA POSTQUIRURGICA DEL CNCER DE COLON SOBRE LA BASE DE VARIABLES MOLECULARES Y CLNICAS: ANTECEDENTES:La calculadora clínica del Memorial Sloan Kettering para la estimación de la probabilidad de ausencia de recurrencia del cáncer de colon sobre la base de variables clínicas y moleculares, se desarrolló en un momento en que las pruebas para la inestabilidad de microsatélites se realizaban de forma selectiva, basadas en la edad del paciente, los antecedentes familiares y las características histológicas. Se asumía la estabilidad micro satelital si no se realizaba ninguna prueba.OBJETIVO:El objetivo de este estudio fue validar la calculadora en una cohorte de pacientes a los que se les había realizado la prueba de inestabilidad de microsatélites.DISEÑO:Análisis de cohorte retrospectivo.AJUSTE:Centro integral de cáncer.PACIENTES:Pacientes consecutivos con cáncer de colon que fueron sometidos a resección curativa por cáncer de colon en estadios I, II o III entre los años 2017 y 2019.PRINCIPALES MEDIDAS DE RESULTADO:La precisión predictiva de la calculadora fue evaluada mediante el índice de concordancia y un gráfico de calibración de la ausencia de recurrencia predecida versus la real a los 3 años tras la cirugía. A los efectos de un análisis secundario de sensibilidad, la presencia de depósito(s) tumoral(es) (categoría de enfermedad N1c) se consideró equivalente a un ganglio linfático positivo (categoría N1a).RESULTADOS:Con una mediana de seguimiento de 32 meses entre los supervivientes, el índice de concordancia para los 745 pacientes de la cohorte fue de 0,748 (intervalo de confianza del 95 %, 0,693 a 0,801), y una gráfica de recurrencias previstas versus observadas se acercó a la diagonal de 45°, indicando una buena discriminación y calibración. En el análisis secundario de sensibilidad para depósitos tumorales, el índice de concordancia fue de 0,755 (intervalo de confianza del 95 %, 0,700 a 0,806).LIMITACIONES:Diseño retrospectivo, institución única.CONCLUSIONES:Estos resultados, basados en la inclusión real del estado de estabilidad de microsatélites en lugar de imputado y la presencia de depósitos tumorales, confirman la precisión predictiva y la confiabilidad de la calculadora. (Traducción-Dr Osvaldo Gauto ).

Anal Adenocarcinoma Treated in the Era of Total Neoadjuvant Therapy and Nonoperative Management.

BACKGROUND: Anal adenocarcinoma bears a treatment strategy unique to other anal cancers. OBJECTIVE: This study aimed to describe oncologic outcomes of total neoadjuvant therapy followed by watch-and-wait approach for anal adenocarcinoma. DESIGN: Retrospective analysis. SETTINGS: This study was conducted at a comprehensive cancer center. PATIENTS: Patients with anal adenocarcinoma treated between 2004 and 2019 were selected. INTERVENTIONS: Fifty-four patients received neoadjuvant therapy and were divided into 2 groups according to their treatment strategy: total neoadjuvant therapy versus single neoadjuvant modality therapy. MAIN OUTCOME MEASURES: Organ preservation, tumor regrowth, local failure, distant metastasis rates, recurrence-free survival, and overall survival. RESULTS: This study included 70 patients with anal adenocarcinoma. Fifty-four patients (77%) received neoadjuvant therapy, of whom 30 (42%) received total neoadjuvant therapy and 24 (34%) received single neoadjuvant modality. Twenty-three (33%) patients achieved complete clinical response and were managed by watch-and-wait approach. The proportion of patients able to continue to watch-and-wait approach was higher after receiving total neoadjuvant therapy (60%) compared with single neoadjuvant modality therapy (20%; p = 0.004). A tumor regrowth rate of 22% was observed in the total neoadjuvant therapy group. The 5-year overall survival rate was 70% (95% CI, 59%-83%), including 61% (95% CI, 42%-88%) for the total neoadjuvant therapy and 65% (95% CI, 48%-88%) for the single neoadjuvant modality groups. Colostomy was avoided in 50% of patients who received total neoadjuvant therapy and 83% of watch-and-wait patients. Five-year recurrence-free survival rates of 55% (95% CI, 39%-79%) and 30% (95% CI, 15%-58%) were observed in the total neoadjuvant therapy and single neoadjuvant modality groups. LIMITATIONS: Retrospective nature. CONCLUSIONS: This is the first report in the literature describing the safety and feasibility of nonoperative management for anal adenocarcinoma. Anal adenocarcinoma treated with total neoadjuvant therapy and nonoperative management achieve regrowth rates comparable to those observed in rectal cancer, with oncologic outcomes similar to those of traditional treatment strategies. See Video Abstract . ADENOCARCINOMA ANAL TRATADO EN LA ERA DE LA TERAPIA NEOADYUVANTE TOTAL Y EL TRATAMIENTO NO QUIRRGICO: ANTECEDENTES:El adenocarcinoma anal conlleva una estrategia de tratamiento único para otros cánceres anales.OBJETIVO:Describir los resultados oncológicos de la terapia neoadyuvante total seguida de observar y esperar en adenocarcinoma anal.DISEÑO:Análisis retrospectivo.AJUSTE:Este estudio se llevó a cabo en un centro oncológico integral.PACIENTES:Se seleccionaron pacientes con adenocarcinoma anal tratados entre 2004-2019.INTERVENCIONES:Cincuenta y cuatro pacientes recibieron terapia neoadyuvante y se dividieron en dos grupos según su estrategia de tratamiento: terapia neoadyuvante total versus terapia de modalidad neoadyuvante única.PRINCIPALES MEDIDAS DE RESULTADO:Preservación de órganos, recurrencia tumoral, falla local, tasas de metástasis a distancia, libre de recurrencia y supervivencia general.RESULTADOS:El estudio incluyó a 70 pacientes con adenocarcinoma anal. Cincuenta y cuatro pacientes (77%) recibieron terapia neoadyuvante, de los cuales 30 (42%) recibieron terapia neoadyuvante total y 24 (34%) recibieron modalidad neoadyuvante única. Veintitrés (33%) pacientes presentaron una respuesta clínica completa y fueron tratados con vigilancia y espera. La proporción de pacientes capaces de continuar en observar y esperar fue mayor después de recibir terapia neoadyuvante total (60%) en comparación con la terapia de modalidad neoadyuvante única (20%) ( p = 0,004). Se observó una tasa de recurrencia tumoral del 22% en el grupo de terapia neoadyuvante total. La tasa de supervivencia general a 5 años fue del 70% (IC95% 59%-83 %), incluido el 61% (IC95% 42%-88%) para la terapia neoadyuvante total y el 65% (IC95% 48%-88%) para grupos de modalidad neoadyuvante única. Se evitó la colostomía en el 50% de los pacientes que recibieron terapia neoadyuvante total y el 83% de los pacientes en observar y esperar. Se observaron tasas de supervivencia libre de recurrencia a cinco años del 55% (IC95% 39%-79%) y del 30% (IC95% 15%-58%) en los grupos de terapia neoadyuvante total y modalidad neoadyuvante única, respectivamente.LIMITACIONES:Diseño retrospectivo.CONCLUSIONES:Este es el primer informe en la literatura que describe la seguridad y viabilidad del tratamiento no quirúrgico del adenocarcinoma anal. El adenocarcinoma anal tratado con terapia neoadyuvante total y manejo no quirúrgico logra tasas de recurrencia comparables a las observadas en el cáncer de recto, con resultados oncológicos similares a las estrategias de tratamientos tradicionales. (Traducción-Dr. Fidel Ruiz Healy ).

Tumour deposits are independently associated with recurrence in colon cancer.

AIM: Tumour deposits are focal aggregates of cancer cells in pericolic fat and mesentery, distinct from vessels, nerves and lymphatics. Their presence upstages lymph node negative patients but is ignored in lymph node positive patients. We investigated the clinicopathological factors associated with tumour deposits and their impact on recurrence in lymph node positive and negative patients. METHOD: Clinicopathological variables were collected from the medical records of patients with Stage I-III colon cancer who underwent resection in 2017-2019. Pathology was reviewed by a gastrointestinal pathologist. Patients with rectal cancer, metastasis, and concurrent malignancy were excluded. RESULTS: Tumour deposits were noted in 69 (9%) of 770 patients. They were associated with the presence of lymph node metastasis, advanced T category, poorly differentiated tumours, microsatellite stable subtype and lymphovascular and perineural invasion (p < 0.05). The presence of tumour deposits (hazard ratio 2.48, 95% CI 1.49-4.10) and of lymph node metastasis (hazard ratio 3.04, 95% CI 1.72-5.37) were independently associated with decreased time to recurrence. There was a weak correlation (0.27) between the number of tumour deposits and the number of positive lymph nodes. CONCLUSION: Tumour deposits are associated with more advanced disease and high-risk pathological features. The presence of tumour deposits and lymph node metastasis were found to be independent risk factors for decreased time to recurrence. A patient with both lymph node metastasis and tumour deposits is more than twice as likely to have recurrence compared with a patient with only lymph node metastasis. Tumour deposits independently predict recurrence and should not be ignored in lymph node positive patients.

Younger Patients with Colon Cancer are More Likely to Experience Financial Toxicity Than Older Patients.

BACKGROUND: The incidence of young-onset colon cancer is increasing. This study investigated the extent to which financial hardships associated with colon cancer care are associated with patient age. METHODS: A consecutive sample of patients with non-metastatic colon cancer who underwent resection at a comprehensive cancer center between 2017 and 2019 were retrospectively enrolled from a clinical database. Patients with one or more of the following events associated with their colon cancer care were categorized as having experienced financial toxicity: two or more bills sent to collections, application for a payment plan, settlement, bankruptcy, or enrollment in a financial assistance program. RESULTS: Of 764 patients identified, 157 (21 %) experienced financial toxicity. In a univariable analysis, financial toxicity was significantly associated with younger age, female sex, nonpartnered marital status, and median income by ZIP code area (p < 0.05). A multivariable analysis showed that with each 10-year decrease in patient age, the odds of financial toxicity increased by 30 % (odds ratio [OR], 1.30; 95 % confidence interval [CI], 1.14-1.48). With each $50,000 decrease in median income by ZIP code area, the odds of financial toxicity increased by 35 % (OR, 1.35; 95 % CI, 1.05-1.74). CONCLUSIONS: Younger patients with colon cancer are at greater risk for financial toxicity than older patients. As this population continues to grow, so will the need for timely and effective financial support mechanisms.

Lymph Node Metastases and Associated Recurrence-Free Survival in Microsatellite Stable and Unstable Colon Cancer.

BACKGROUND: In contrast to microsatellite stable (MSS) colon cancer, predictors of lymph node metastases and their association with recurrence are not well-defined in microsatellite instability (MSI) colon cancer. METHODS: A cohort of nonmetastatic colon cancer patients undergoing surgery between 2015 and 2021 were evaluated for predictors of lymph node metastases (LNMs) and their association with recurrence-free survival (RFS). RESULTS: Of 1466 patients included in the analyses, 361 (25 %) had MSI. Compared with MSS, MSI was associated with earlier stage, fewer LNMs in the patients with N1 or N2 disease, and fewer high-risk features. Compared with the T3-T4 MSS patients, the odds ratios for LNM were 0.52 (95% confidence interval [CI], 0.38-0.71) for the T3-T4 MSI patients, 0.27 (95% CI, 0.38-0.71) for the T1-T2 MSS patients, and 0.15 (95 % CI, 0.08-0.26) for the T1-T2 MSI patients. In both groups, LNMs were associated with T category, patient age, and venous, lymphatic, or perineural invasion. In the MSS patients, LNMs were additionally associated with patient sex and histologic grade. Compared with the MSS patients, the MSI patients with N0 and N1 disease had a better 3-year RFS. However, the MSI patients with N2 disease had a lower rate of 3-year RFS than the MSS patients (hazard ratio, 19.75 vs 4.49). CONCLUSIONS: In MSI colon cancer, LNMs are 50 % less prevalent, but the factors associated with LNM are like those in MSS colon cancer. The improved prognosis traditionally associated with early-stage MSI colon cancers dissipates with four or more LNMs. These findings should be taken into consideration by clinicians selecting the most appropriate course of treatment for MSI colon cancer.

MRI Assessment of Extramural Venous Invasion Before and After Total Neoadjuvant Therapy for Locally Advanced Rectal Cancer and Its Association with Disease-Free and Overall Survival.

BACKGROUND: Extramural venous invasion (EMVI) on baseline MRI is associated with poor prognosis in patients with locally advanced rectal cancer. This study investigated the association of persistent EMVI after total neoadjuvant therapy (TNT) (chemoradiotherapy and systemic chemotherapy) with survival. METHODS: Baseline MRI, post-TNT MRI, and surgical pathology data from 175 patients with locally advanced rectal cancer who underwent TNT and total mesorectal excision between 2010 and 2017 were retrospectively analyzed for evidence of EMVI. Two radiologists assessed EMVI status with disagreement adjudicated by a third. Pathologic EMVI status was assessed per departmental standards. Cox regression models evaluated the associations between EMVI and disease-free and overall survival. RESULTS: EMVI regression on both post-TNT MRI and surgical pathology was associated with disease-free survival (hazard ratio, 0.17; 95% confidence interval (CI), 0.04-0.64) and overall survival (hazard ratio, 0.11; 95% CI, 0.02-0.68). In an exploratory analysis of 35 patients with EMVI on baseline MRI, only six had EMVI on pathology compared with 18 on post-TNT MRI; these findings were not associated (p = 0.2). Longer disease-free survival was seen with regression on both modalities compared with remaining positive. Regression on pathology alone, independent of MRI EMVI status, was associated with similar improvements in survival. CONCLUSIONS: Baseline EMVI is associated with poor prognosis even after TNT. EMVI regression on surgical pathology is common even with persistent EMVI on post-TNT MRI. EMVI regression on surgical pathology is associated with improved DFS, while the utility of post-TNT MRI EMVI persistence for decision-making and prognosis remains unclear.

Characteristics of Mismatch Repair-Deficient Colon Cancer in Relation to Mismatch Repair Protein Loss, Hypermethylation Silencing, and Constitutional and Biallelic Somatic Mismatch Repair Gene Pathogenic Variants.

BACKGROUND: Mismatch repair-deficient colon cancer is heterogeneous. Differentiating inherited constitutional variants from somatic genetic alterations and gene silencing is important for surveillance and genetic counseling. OBJECTIVE: This study aimed to determine the extent to which the underlying mechanism of loss of mismatch repair influences molecular and clinicopathologic features of microsatellite instability-high colon cancer. DESIGN: This is a retrospective analysis. SETTINGS: This study was conducted at a comprehensive cancer center. PATIENTS: Patients with microsatellite instability-high colon cancer of stage I, II, or III were included. INTERVENTION: Patients underwent a curative surgical resection. MAIN OUTCOME MEASURES: The main outcome measures were hypermethylation of the MLH1 promoter, biallelic inactivation, constitutional pathogenic variants, and loss of specific mismatch repair proteins. RESULTS: Of the 157 identified tumors with complete genetic analysis, 66% had hypermethylation of the MLH1 promoter, 18% had constitutional pathogenic variants, (Lynch syndrome), 11% had biallelic somatic mismatch repair gene pathogenic variants, and 6% had unexplained high microsatellite instability. The distribution of mismatch repair loss was as follows: MLH1 and PMS2 co-loss, 79% of the tumors; MSH2 and MSH6 co-loss, 10%; MSH6 alone, 3%; PMS2 alone, 2%; other combinations, 2%; no loss, 2%. Tumor mutational burden was lowest in MLH1- and PMS2-deficient tumors. MSH6-deficient tumors had the lowest levels of tumor-infiltrating lymphocytes, lowest MSI scores, and fewest frameshift deletions. Patients with MLH1 promoter hypermethylation were significantly more likely to be older and female and to have right-sided colon lesions than patients with biallelic inactivation. Mutation was the most prevalent second hit in tumors with biallelic inactivation and tumors of patients with Lynch syndrome. LIMITATIONS: This study was limited by potential selection or referral bias, missing data for some patients, and relatively small sizes of some subgroups. CONCLUSIONS: Clinical characteristics of mismatch repair-deficient colon cancer vary with the etiology of microsatellite instability, and its molecular characteristics vary with the affected mismatch repair protein. See Video Abstract at http://links.lww.com/DCR/B984 . CARACTERSTICAS DEL CNCER DE COLON CON DEFICIENCIA EN LA REPARACIN DE ERRORES DE EMPAREJAMIENTO EN RELACIN CON LA PRDIDA DE PROTENAS MMR, SILENCIAMIENTO DE LA HIPERMETILACIN Y LAS VARIANTES PATGENAS SOMTICAS DE GENES MMR CONSTITUCIONAL Y BIALLICO: ANTECEDENTES:El cáncer de colon deficiente en la reparación de errores de emparejamiento es heterogéneo. La diferenciación de las variantes constitucionales heredadas de las alteraciones genéticas somáticas y el silenciamiento de genes es importante para la vigilancia y el asesoramiento genético.OBJETIVO:Determinar hasta qué punto el mecanismo subyacente de pérdida de reparación de desajustes influye en las características moleculares y clinicopatológicas del cáncer de colon con alta inestabilidad de microsatélites.DISEÑO:Análisis retrospectivo.ESCENARIO:Centro integral de cáncer.PACIENTES:Pacientes con cáncer de colon con inestabilidad de microsatélites alta en estadio I, II, o III.INTERVENCIÓN:Resección quirúrgica con intención curativa.PRINCIPALES RESULTADOS Y MEDIDAS:Hipermetilación del promotor MLH1, inactivación bialélica, variante patógena constitucional y pérdida de proteínas específicas reparadoras de desajustes.RESULTADOS:De los 157 tumores identificados con un análisis genético completo, el 66 % tenía hipermetilación del promotor MLH1, el 18 % tenía una variante patogénica constitucional (síndrome de Lynch), el 11 % tenía variantes patogénicas somáticas bialélicas de algún gen MMR y el 6 % tenía una alta inestabilidad de microsatélites sin explicación. La distribución de la pérdida según la proteína de reparación del desajuste fue la siguiente: pérdida conjunta de MLH1 y PMS2, 79 % de los tumores; co-pérdida de MSH2 y MSH6, 10%; MSH6 solo, 3%; PMS2 solo, 2%; otras combinaciones, 2%; sin pérdida, 2%. La carga mutacional del tumor fue más baja en los tumores deficientes en MLH1 y PMS2. Los tumores con deficiencia de MSH6 tenían los niveles más bajos de linfocitos infiltrantes de tumores, las puntuaciones más bajas del sensor de IMS y la menor cantidad de deleciones por cambio de marco. Los pacientes con hipermetilación del promotor MLH1 tenían significativamente más probabilidades de ser mayores y mujeres y de tener lesiones en el colon derecho que los pacientes con inactivación bialélica. La mutación fue el segundo golpe más frecuente en tumores con inactivación bialélica y tumores de pacientes con síndrome de Lynch.LIMITACIONES:Sesgo potencial de selección o referencia, datos faltantes para algunos pacientes y tamaños relativamente pequeños de algunos subgrupos.CONCLUSIONES:Las características clínicas del cáncer de colon deficiente en reparación de desajustes varían con la etiología de la inestabilidad de microsatélites, y sus características moleculares varían con la proteína de reparación de desajustes afectada. Vea Resumen de video en http://links.lww.com/DCR/B984 . (Traducción-Dr. Felipe Bellolio ).

Comparison of Robotic, Laparoscopic, and Open Resections of Nonmetastatic Colon Cancer.

BACKGROUND: Laparoscopic resection for colon cancer has not been associated with improvements in oncological outcomes in comparison to open resection. Robotic resections are associated with increased lymph node yield and radicality of mesenteric resection in patients with right-sided tumors. It is unclear whether lymph node yield is higher in robotic resections in other parts of the colon and whether higher lymph node yield is associated with improved survival. OBJECTIVE: To compare survival rates between robotic, laparoscopic, and open resections in a large cohort of patients with nonmetastatic colon cancer. DESIGN: This is a retrospective observational study. SETTING: A single comprehensive cancer center. PATIENTS: Patients who underwent resection of nonmetastatic primary colon cancer between January 2006 and December 2018. MAIN OUTCOME MEASURES: Univariable and multivariable models were used to identify predictors of disease-free and overall survival. Lymph node yield and perioperative outcomes were compared between operative approaches. RESULTS: There were 2398 patients who met the inclusion criteria: 699 (29%) underwent open, 824 (34%) underwent laparoscopic, and 875 (36%) underwent robotic resection. The median follow-up was 3.8 years (45.4 months). Robotic surgery was associated with higher lymph node yield and radicality of mesenteric resection. On multivariable analysis, the surgical approach was not associated with a difference in disease-free or overall survival. Minimally invasive colectomy was associated with fewer complications and shorter length of stay in comparison to open surgery. In a direct comparison between the 2 minimally invasive approaches, robotic colectomy was associated with fewer complications, shorter length of stay, and lower conversion rate than laparoscopy. LIMITATIONS: This was a single-center retrospective study. CONCLUSIONS: Our data indicate that the 3 surgical approaches are similarly effective in treating primary resectable colon cancer and that differences in outcomes are observed primarily in the early postoperative period. See Video Abstract at http://links.lww.com/DCR/C115 . COMPARACIN DE RESECCIONES ROBTICAS, LAPAROSCPICAS Y ABIERTAS DE CNCER DE COLON NO METASTSICO: ANTECEDENTES:La resección laparoscópica para el cáncer de colon no se ha asociado con mejoras en los resultados oncológicos en comparación con la resección abierta. Las resecciones robóticas se asocian con un mayor rendimiento de los ganglios linfáticos y la radicalidad de la resección mesentérica en pacientes con tumores del lado derecho. No está claro si la cosecha ganglionar es mayor en las resecciones robóticas en otras partes del colon y si un mayor rendimiento de los ganglios linfáticos se asocia con una mejor supervivencia.OBJETIVO:Comparar las tasas de supervivencia entre resecciones robóticas, laparoscópicas y abiertas en una gran cohorte de pacientes con cáncer de colon no metastásico.DISEÑO:Este es un estudio observacional retrospectivo.ESCENARIO:Este estudio se realizó en un único centro oncológico integral.PACIENTES:Pacientes que se sometieron a resección de cáncer de colon primario no metastásico entre enero de 2006 y diciembre de 2018.PRINCIPALES MEDIDAS DE RESULTADO:Se utilizaron modelos univariables y multivariables para identificar predictores de supervivencia libre de enfermedad y global. La cosecha ganglionar y los resultados perioperatorios se compararon entre los abordajes quirúrgicos.RESULTADOS:Hubo 2398 pacientes que cumplieron con los criterios de inclusión: 699 (29%) se sometieron a cirugía abierta, 824 (34%) se sometieron a resección laparoscópica y 875 (36%) se sometieron a resección robótica. La mediana de seguimiento fue de 3,8 años (45,4 meses). La cirugía robótica se asoció con una mayor cosecha ganglionar y la radicalidad de la resección mesentérica. En el análisis multivariable, el abordaje quirúrgico no se asoció con una diferencia en la supervivencia general o libre de enfermedad. La colectomía mínimamente invasiva se asoció con menos complicaciones y una estancia más corta en comparación con la cirugía abierta. En una comparación directa entre los dos enfoques mínimamente invasivos, la colectomía robótica se asoció con menos complicaciones, una estancia más corta y una tasa de conversión más baja que la laparoscopia.LIMITACIONES:Este fue un estudio retrospectivo de un solo centro.CONCLUSIONES:Nuestros datos indican que los tres enfoques quirúrgicos son igualmente efectivos en el tratamiento del cáncer de colon resecable primario y que las diferencias en los resultados se observan principalmente en el período posoperatorio temprano. Consulte Video Resumen en http://links.lww.com/DCR/C115 . (Traducción-Dr. Felipe Bellolio ).

American Joint Committee on Cancer acceptance criteria for inclusion of risk models for individualized prognosis in the practice of precision medicine.

The American Joint Committee on Cancer (AJCC) has increasingly recognized the need for more personalized probabilistic predictions than those delivered by ordinal staging systems, particularly through the use of accurate risk models or calculators. However, judging the quality and acceptability of a risk model is complex. The AJCC Precision Medicine Core conducted a 2-day meeting to discuss characteristics necessary for a quality risk model in cancer patients. More specifically, the committee established inclusion and exclusion criteria necessary for a risk model to potentially be endorsed by the AJCC. This committee reviewed and discussed relevant literature before creating a checklist unique to this need of AJCC risk model endorsement. The committee identified 13 inclusion and 3 exclusion criteria for AJCC risk model endorsement in cancer. The emphasis centered on performance metrics, implementation clarity, and clinical relevance. The facilitation of personalized probabilistic predictions for cancer patients holds tremendous promise, and these criteria will hopefully greatly accelerate this process. Moreover, these criteria might be useful for a general audience when trying to judge the potential applicability of a published risk model in any clinical domain. CA Cancer J Clin 2016;66:370-374. © 2016 American Cancer Society.

Survival After Induction Chemotherapy and Chemoradiation Versus Chemoradiation and Adjuvant Chemotherapy for Locally Advanced Rectal Cancer.

BACKGROUND: Total neoadjuvant therapy (TNT) improves tumor response in locally advanced rectal cancer (LARC) patients compared to neoadjuvant chemoradiotherapy alone. The effect of TNT on patient survival has not been fully investigated. MATERIALS AND METHODS: This was a retrospective case series of patients with LARC at a comprehensive cancer center. Three hundred and eleven patients received chemoradiotherapy (chemoRT) as the sole neoadjuvant treatment and planned adjuvant chemotherapy, and 313 received TNT (induction fluorouracil and oxaliplatin-based chemotherapy followed by chemoradiotherapy in the neoadjuvant setting). These patients then underwent total mesorectal excision or were entered in a watch-and-wait protocol. The proportion of patients with complete response (CR) after neoadjuvant therapy (defined as pathological CR or clinical CR sustained for 2 years) was compared by the χ2 test. Disease-free survival (DFS), local recurrence-free survival, distant metastasis-free survival, and overall survival were assessed by Kaplan-Meier analysis and log-rank test. Cox regression models were used to further evaluate DFS. RESULTS: The rate of CR was 20% for chemoRT and 27% for TNT (P=.05). DFS, local recurrence-free survival, metastasis-free survival, and overall survival were no different. Disease-free survival was not associated with the type of neoadjuvant treatment (hazard ratio [HR] 1.3; 95% confidence interval [CI] 0.93-1.80; P = .12). CONCLUSIONS: Although TNT does not prolong survival than neoadjuvant chemoradiotherapy plus intended postoperative chemotherapy, the higher response rate associated with TNT may create opportunities to preserve the rectum in more patients with LARC.

Adoption of Organ Preservation and Surgeon Variability for Patients with Rectal Cancer Does Not Correlate with Worse Survival.

BACKGROUND AND OBJECTIVES: Watch-and-wait is variably adopted by surgeons and the impact of this on outcomes is unknown. We compared the disease-free survival and organ preservation rates of locally advanced rectal cancer patients treated by expert colorectal surgeons at a comprehensive cancer center. METHODS: This study included retrospective data on patients diagnosed with stage II/III rectal adenocarcinoma from January 2013 to June 2017 who initiated neoadjuvant therapy (either with chemoradiation, chemotherapy, or a combination of both) and were treated by an expert colorectal surgeon. RESULTS: Overall, 444 locally advanced rectal cancer patients managed by five surgeons were included. Tumor distance from the anal verge, type of neoadjuvant therapy, and organ preservation rates varied by treating surgeon. There was no difference in disease-free survival after stratifying by the treating surgeon (p = 0.2). On multivariable analysis, neither the type of neoadjuvant therapy nor the treating surgeon was associated with disease-free survival. CONCLUSIONS: While neoadjuvant therapy type and organ preservation rates varied among surgeons, there were no meaningful differences in disease-free survival. These data suggest that among expert colorectal surgeons, differing thresholds for selecting patients for watch-and-wait do not affect survival.

Technical feasibility of salvage endoscopic submucosal dissection after chemoradiation for locally advanced rectal adenocarcinoma.

BACKGROUND AND AIMS: The standard treatment of locally advanced rectal cancer is chemoradiation (CRT) followed by proctectomy and adjuvant chemotherapy. However, there is an emerging role for nonsurgical management after CRT or total neoadjuvant therapy (TNT) consisting of CRT and neoadjuvant chemotherapy. Endoscopic submucosal dissection (ESD) after CRT or TNT for rectal cancer, termed "salvage ESD," may be a viable nonsurgical option for carefully selected patients. We aimed to evaluate the feasibility and safety of salvage ESD. METHODS: A retrospective chart review of cases of salvage ESD for locally advanced rectal cancer and standard ESD for rectal tumors without prior CRT from July 2018 to August 2020 at our institution was performed. Clinical factors and imaging, procedural, and pathology results were collected and compared. RESULTS: Twelve salvage ESD cases were compared with 27 standard ESD cases. Before CRT, 83.3% of lesions in the salvage ESD group were initially clinically staged as T3. The en-bloc resection rates were 92.7% and 91.7% (P = 1.00) and R0 resection rates 66.7% and 75.0% (P = .55) for the standard and salvage groups, respectively. In the salvage ESD group, no adverse events were observed, and 75.0% of the adenocarcinomas in the salvage ESD group had morphologically changed to hyperplasia or adenoma after CRT, with no identifiable lesions greater than T1 tumor depth. CONCLUSIONS: Salvage ESD for locally advanced rectal cancer is technically feasible with low adverse event rates. There may be a diagnostic role in salvage ESD in assessing pathologic response to CRT and a possible therapeutic role in resection of residual lesions with the potential to avoid surgery.

Occurrence of peritoneal carcinomatosis in patients with rectal cancer undergoing staging pelvic MRI: clinical observations.

OBJECTIVES: Describe the cumulative incidence (CUIN) of peritoneal carcinomatosis (PC) and survival in patients presenting with advanced rectal cancer at staging pelvic MRI. METHODS: From 2013 to 2018, clinicopathologic records of patients with pretreatment rectal MRI clinical (c)T3c, cT3d, cT4a, and cT4b primary rectal adenocarcinoma were retrospectively reviewed by two radiologists. Standard MRI descriptors and pathologic stages were recorded. Recurrence-free (RFS) and overall survival (OS) were estimated using the Kaplan-Meier method. Development of PC was explored using competing risk analysis. Differences in survival were compared using the log-rank test. Gray's test was used to test for differences in CUIN of PC. RESULTS: Three hundred forty-three patients (147 women; median age, 56 years) had MRI stages cT3cd, n = 170; cT4a, n = 40; and cT4b, n = 133. Median follow-up among survivors was 27 months (0.36-70 months). For M1 patients, OS differed only by cT stage (2-year OS: cT3 88.1%, cT4a 79.1%, cT4b 64.7%, p = 0.045). For M0 patients, OS and RFS differed only by pathological (p)T stage. We observed a statistically significant difference in the cumulative incidence of PC by cT stage (2-year CUIN: cT3 3.2%, cT4a 8.5%, cT4b 1.6%, p = 0.01), but not by pT stage. Seventy-nine patients (23%) presented with metastatic disease (M1), eight with PC (2.3%). Overall, eight patients presented with PC (cT4a: n = 4, other stages: n = 4) and 22 developed PC (cT4a: n = 5, other stages: n = 17). CONCLUSIONS: PC is uncommon in rectal cancer. MRI-based T stage exhibited an overall association with the cumulative incidence of PC, and descriptively, cT4a stage appears to have the highest CUIN. KEY POINTS: • In a retrospective study of 343 patients with rectal cancer undergoing baseline MRI and clinical follow-up, we found that peritoneal carcinomatosis was rare. • We observed a significant overall association between PC at presentation and cT stage that appeared to be driven by the higher proportion of cT4a patients presenting with PC. • Among patients that did not present with PC, we observed a significant overall association between time to PC and cT stage that may be driven by the higher cumulative incidence of PC in cT4a patients.

MRI radiomics features of mesorectal fat can predict response to neoadjuvant chemoradiation therapy and tumor recurrence in patients with locally advanced rectal cancer.

OBJECTIVE: To interrogate the mesorectal fat using MRI radiomics feature analysis in order to predict clinical outcomes in patients with locally advanced rectal cancer. METHODS: This retrospective study included patients who underwent neoadjuvant chemoradiotherapy for locally advanced rectal cancer from 2009 to 2015. Three radiologists independently segmented mesorectal fat on baseline T2-weighted axial MRI. Radiomics features were extracted from segmented volumes and calculated using CERR software, with adaptive synthetic sampling being employed to combat large class imbalances. Outcome variables included pathologic complete response (pCR), local recurrence, distant recurrence, clinical T-category (cT), post-treatment T category (ypT), and post-treatment N category (ypN). A maximum of eight most important features were selected for model development using support vector machines and fivefold cross-validation to predict each outcome parameter via elastic net regularization. Diagnostic metrics of the final models were calculated, including sensitivity, specificity, PPV, NPV, accuracy, and AUC. RESULTS: The study included 236 patients (54 ± 12 years, 135 men). The AUC, sensitivity, specificity, PPV, NPV, and accuracy for each clinical outcome were as follows: for pCR, 0.89, 78.0%, 85.1%, 52.5%, 94.9%, 83.9%; for local recurrence, 0.79, 68.3%, 80.7%, 46.7%, 91.2%, 78.3%; for distant recurrence, 0.87, 80.0%, 88.4%, 58.3%, 95.6%, 87.0%; for cT, 0.80, 85.8%, 56.5%, 89.1%, 49.1%, 80.1%; for ypN, 0.74, 65.0%, 80.1%, 52.7%, 87.0%, 76.3%; and for ypT, 0.86, 81.3%, 84.2%, 96.4%, 46.4%, 81.8%. CONCLUSION: Radiomics features of mesorectal fat can predict pathological complete response and local and distant recurrence, as well as post-treatment T and N categories. KEY POINTS: • Mesorectal fat contains important prognostic information in patients with locally advanced rectal cancer (LARC). • Radiomics features of mesorectal fat were significantly different between those who achieved complete vs incomplete pathologic response (accuracy 83.9%, 95% CI: 78.6-88.4%). • Radiomics features of mesorectal fat were significantly different between those who did vs did not develop local or distant recurrence (accuracy 78.3%, 95% CI: 72.0-83.7% and 87.0%, 95% CI: 81.6-91.2% respectively).

MRI at Restaging After Neoadjuvant Therapy for Rectal Cancer Overestimates Circumferential Resection Margin Proximity as Determined by Comparison With Whole-Mount Pathology.

BACKGROUND: Current guidelines recommend restaging with MRI after neoadjuvant therapy for rectal cancer, but the accuracy of restaging MRI in estimating circumferential margin involvement requires additional clarification. OBJECTIVE: The objective of this study was to measure the accuracy of circumferential resection margin assessment by MRI after neoadjuvant therapy and identify characteristics associated with accuracy. DESIGN: MRI data were retrospectively analyzed for concordance with the findings of whole-mount pathology analysis of the corresponding surgical specimens. Univariate and multivariate logistic regression analyses were performed to identify characteristics associated with accuracy. SETTING: This study was conducted at a comprehensive cancer center. PATIENTS: Included in the study were consecutive patients who underwent total mesorectal excision for rectal cancer between January 2018 and March 2020 after receiving neoadjuvant therapy and undergoing restaging with MRI. MAIN OUTCOME MEASURES: The primary outcome of this study included accuracy, sensitivity, specificity, and positive and negative predictive values for categorizing the circumferential resection margin as threatened; mean and paired mean differences were in proximity of the margin. RESULTS: Of the 94 patients included in the analysis, 39 (41%) had a threatened circumferential resection margin according to MRI at restaging, but only 17 (18%) had a threatened margin based on pathology. The accuracy of MRI in identifying a threatened margin was 63.8%, with margin proximity overestimated by 0.4 cm on average. In multivariate logistic regression, anterior location of the margin and tumor proximity to the anal verge were independently associated with reduced MRI accuracy. LIMITATIONS: A limitation was the retrospective design at a single institution. CONCLUSIONS: The knowledge that MRI-based restaging after neoadjuvant therapy overestimates circumferential margin proximity may render some surgical radicality unnecessary and thereby help avoid the associated morbidity. With the recognition that MRI-based assessment of margin proximity may not be reliable for anterior margin and for distal tumors, radiologists may want to use greater caution in interpreting images of tumors with these characteristics and to acknowledge the uncertainty in their reports. See Video Abstract at http://links.lww.com/DCR/B814. LA IRM EN LA REESTADIFICACIN LUEGO DE TERAPIA NEOADYUVANTE EN EL CNCER DE RECTO SOBRESTIMA LA PROXIMIDAD DEL MARGEN DE RESECCIN CIRCUNFERENCIAL SEGN LO DETERMINADO COMPARATIVAMENTE CON LA PIEZA DE ANATOMOPATOLOGA: ANTECEDENTES:Las pautas actuales recomiendan la re-estadificación por medio de la resonancia magnética luego de terapia neoadyuvante en los casos de cáncer de recto, pero la precisión de la reevaluación con la IRM para estimar el grado de implicación del margen circunferencial requiere aclaraciones adicionales.OBJETIVO:Medir el grado de exactitud en la evaluación del margen de resección circunferencial mediante resonancia magnética después de la terapia neoadyuvante e identificar las características asociadas con la precisión.DISEÑO:Se analizaron retrospectivamente los datos de resonancia magnética para determinar la concordancia entre los hallazgos del análisis de la pieza de anatamopatología y las muestras quirúrgicas correspondientes. Se realizó el análisis de regresión logística univariada y multivariada para identificar las características asociadas con la exactitud.AJUSTE:Centro oncológico integral.PACIENTES:Todos aquellos que se sometieron consecutivamente a una excisión total del mesorrecto por cáncer rectal entre Enero 2018 y Febrero 2020 luego de recibir terapia neoadyuvante y someterse a una re-estadificación por imágenes de resonancia magnética (IRM).PRINCIPALES MEDIDAS DE RESULTADO:La exactitud, la sensibilidad y especificidad; los valores predictivos positivos y negativos para categorizar el margen de resección circunferencial como amenazado; la diferencia media y las medias pareadas de proximidad a los margenes.RESULTADOS:De los 94 pacientes incluidos en el análisis, 39 (41%) tenían un margen de resección circunferencial amenazado según la resonancia magnética en la re-estadificación, pero solo 17 (18%) tenían un margen amenazado basado en la patología. La precisión de la resonancia magnética para identificar un margen amenazado fue del 63,8%, con la proximidad del margen sobreestimada en 0,4 cm en promedio. En la regresión logística multivariada, la ubicación anterior de los bordes de resección y la proximidad del tumor al margen anal se asociaron de forma independiente con la reducción en la precisión de la resonancia magnética.LIMITACIONES:Diseño retrospectivo en una institución única.CONCLUSIONES:El saber que la re-estadificación basada en la IRM, luego de terapia neoadyuvante sobreestima la proximidad de la lesión a los márgenes circunferenciales, hace innecesaria cierta radicalidad quirúrgica complementaria, lo que ayuda a evitar morbilidad asociada. Reconociendo que la evaluación de proximidad de los márgenes de resección basada en la resonancia magnética, no puede ser confiable en casos de márgenes anteriores y en casos de tumores distales. Los radiólogos recomiendan tener más precaución en la interpretación de imágenes de tumores con estas características y reconocen cierto desasosiego en sus informes. Consulte Video Resumen en http://links.lww.com/DCR/B814.