Colorectal cancer screening for average-risk adults: 2018 guideline update from the American Cancer Society.

In the United States, colorectal cancer (CRC) is the fourth most common cancer diagnosed among adults and the second leading cause of death from cancer. For this guideline update, the American Cancer Society (ACS) used an existing systematic evidence review of the CRC screening literature and microsimulation modeling analyses, including a new evaluation of the age to begin screening by race and sex and additional modeling that incorporates changes in US CRC incidence. Screening with any one of multiple options is associated with a significant reduction in CRC incidence through the detection and removal of adenomatous polyps and other precancerous lesions and with a reduction in mortality through incidence reduction and early detection of CRC. Results from modeling analyses identified efficient and model-recommendable strategies that started screening at age 45 years. The ACS Guideline Development Group applied the Grades of Recommendations, Assessment, Development, and Evaluation (GRADE) criteria in developing and rating the recommendations. The ACS recommends that adults aged 45 years and older with an average risk of CRC undergo regular screening with either a high-sensitivity stool-based test or a structural (visual) examination, depending on patient preference and test availability. As a part of the screening process, all positive results on noncolonoscopy screening tests should be followed up with timely colonoscopy. The recommendation to begin screening at age 45 years is a qualified recommendation. The recommendation for regular screening in adults aged 50 years and older is a strong recommendation. The ACS recommends (qualified recommendations) that: 1) average-risk adults in good health with a life expectancy of more than 10 years continue CRC screening through the age of 75 years; 2) clinicians individualize CRC screening decisions for individuals aged 76 through 85 years based on patient preferences, life expectancy, health status, and prior screening history; and 3) clinicians discourage individuals older than 85 years from continuing CRC screening. The options for CRC screening are: fecal immunochemical test annually; high-sensitivity, guaiac-based fecal occult blood test annually; multitarget stool DNA test every 3 years; colonoscopy every 10 years; computed tomography colonography every 5 years; and flexible sigmoidoscopy every 5 years. CA Cancer J Clin 2018;68:250-281. © 2018 American Cancer Society.

Outcomes and potential impact of a virtual hands-on training program on MRI staging confidence and performance in rectal cancer.

OBJECTIVES: To explore the potential impact of a dedicated virtual training course on MRI staging confidence and performance in rectal cancer. METHODS: Forty-two radiologists completed a stepwise virtual training course on rectal cancer MRI staging composed of a pre-course (baseline) test with 7 test cases (5 staging, 2 restaging), a 1-day online workshop, 1 month of individual case readings (n = 70 cases with online feedback), a live online feedback session supervised by two expert faculty members, and a post-course test. The ESGAR structured reporting templates for (re)staging were used throughout the course. Results of the pre-course and post-course test were compared in terms of group interobserver agreement (Krippendorf's alpha), staging confidence (perceived staging difficulty), and diagnostic accuracy (using an expert reference standard). RESULTS: Though results were largely not statistically significant, the majority of staging variables showed a mild increase in diagnostic accuracy after the course, ranging between + 2% and + 17%. A similar trend was observed for IOA which improved for nearly all variables when comparing the pre- and post-course. There was a significant decrease in the perceived difficulty level (p = 0.03), indicating an improved diagnostic confidence after completion of the course. CONCLUSIONS: Though exploratory in nature, our study results suggest that use of a dedicated virtual training course and web platform has potential to enhance staging performance, confidence, and interobserver agreement to assess rectal cancer on MRI virtual training and could thus be a good alternative (or addition) to in-person training. CLINICAL RELEVANCE STATEMENT: Rectal cancer MRI reporting quality is highly dependent on radiologists' expertise, stressing the need for dedicated training/teaching. This study shows promising results for a virtual web-based training program, which could be a good alternative (or addition) to in-person training. KEY POINTS: • Rectal cancer MRI reporting quality is highly dependent on radiologists' expertise, stressing the need for dedicated training and teaching. • Using a dedicated virtual training course and web-based platform, encouraging first results were achieved to improve staging accuracy, diagnostic confidence, and interobserver agreement. • These exploratory results suggest that virtual training could thus be a good alternative (or addition) to in-person training.

Role of dynamic contrast-enhanced MRI in predicting severe acute radiation-induced rectal injury in patients with rectal cancer.

OBJECTIVES: To explore the potential of dynamic contrast-enhanced MRI (DCE-MRI) quantitative parameters in predicting severe acute radiation-induced rectal injury (RRI) in rectal cancer. METHODS: This retrospective study enrolled 49 patients with rectal cancer who underwent neoadjuvant chemoradiotherapy and rectal MRI including a DCE-MRI sequence from November 2014 to March 2021. Two radiologists independently measured DCE-MRI quantitative parameters, including the forward volume transfer constant (Ktrans), rate constant (kep), fractional extravascular extracellular space volume (ve), and the thickness of the rectal wall farthest away from the tumor. These parameters were compared between mild and severe acute RRI groups based on histopathological assessment. Receiver operating characteristic curve analysis was performed to analyze statistically significant parameters. RESULTS: Forty-nine patients (mean age, 54 years ± 12 [standard deviation]; 37 men) were enrolled, including 25 patients with severe acute RRI. Ktrans was lower in severe acute RRI group than mild acute RRI group (0.032 min-1 vs 0.054 min-1; p = 0.008), but difference of other parameters (kep, ve and rectal wall thickness) was not significant between these two groups (all p > 0.05). The area under the receiver operating characteristic curve of Ktrans was 0.72 (95% confidence interval: 0.57, 0.84). With a Ktrans cutoff value of 0.047 min-1, the sensitivity and specificity for severe acute RRI prediction were 80% and 54%, respectively. CONCLUSION: Ktrans demonstrated moderate diagnostic performance in predicting severe acute RRI. CLINICAL RELEVANCE STATEMENT: Dynamic contrast-enhanced MRI can provide non-invasive and objective evidence for perioperative management and treatment strategies in rectal cancer patients with acute radiation-induced rectal injury. KEY POINTS: • To our knowledge, this study is the first to evaluate the predictive value of contrast-enhanced MRI (DCE-MRI) quantitative parameters for severe acute radiation-induced rectal injury (RRI) in patients with rectal cancer. • Forward volume transfer constant (Ktrans), derived from DCE-MRI, exhibited moderate diagnostic performance (AUC = 0.72) in predicting severe acute RRI of rectal cancer, with a sensitivity of 80% and specificity of 54%. • DCE-MRI is a promising imaging marker for distinguishing the severity of acute RRI in patients with rectal cancer.

Ultra-high b-value DWI in rectal cancer: image quality assessment and regional lymph node prediction based on radiomics.

OBJECTIVES: This study aims to evaluate image quality and regional lymph node metastasis (LNM) in patients with rectal cancer (RC) on multi-b-value diffusion-weighted imaging (DWI). METHODS: This retrospective study included 199 patients with RC who had undergone multi-b-value DWI. Subjective (five-point Likert scale) and objective assessments of quality images were performed on DWIb1000, DWIb2000, and DWIb3000. Patients were randomly divided into a training (n = 140) or validation cohort (n = 59). Radiomics features were extracted within the whole volume tumor on ADC maps (b = 0, 1000 s/mm2), DWIb1000, DWIb2000, and DWIb3000, respectively. Five prediction models based on selected features were developed using logistic regression analysis. The performance of radiomics models was evaluated with a receiver operating characteristic curve, calibration, and decision curve analysis (DCA). RESULTS: The mean signal intensity of the tumor (SItumor), signal-to-noise ratio (SNR), and artifact and anatomic differentiability score gradually were decreased as the b-value increased. However, the contrast-to-noise (CNR) on DWIb2000 was superior to those of DWIb1000 and DWIb3000 (4.58 ± 0.86, 3.82 ± 0.77, 4.18 ± 0.84, p < 0.001, respectively). The overall image quality score of DWIb2000 was higher than that of DWIb3000 (p < 0.001) and showed no significant difference between DWIb1000 and DWIb2000 (p = 0.059). The area under curve (AUC) value of the radiomics model based on DWIb2000 (0.728) was higher than conventional ADC maps (0.690), DWIb1000 (0.699), and DWIb3000 (0.707), but inferior to multi-b-value DWI (0.739) in predicting LNM. CONCLUSION: DWIb2000 provides better lesion conspicuity and LNM prediction than DWIb1000 and DWIb3000 in RC. CLINICAL RELEVANCE STATEMENT: DWIb2000 offers satisfactory visualization of lesions. Radiomics features based on DWIb2000 can be applied for preoperatively predicting regional lymph node metastasis in rectal cancer, thereby benefiting the stratified treatment strategy. KEY POINTS: Lymph node staging is required to determine the best treatment plan for rectal cancer. DWIb2000 provides superior contrast-to-noise ratio and lesion conspicuity and its derived radiomics best predict lymph node metastasis. DWIb2000 may be recommended as the optimal b-value in rectal MRI protocol.

Does Tri-Staple™ technology reduce the risk of anastomotic leakage in colorectal surgery? A propensity score matching analysis.

BACKGROUND AND OBJECTIVES: This study evaluates the Tri-Staple™ technology in colorectal anastomosis. METHODS: Patients who underwent rectosigmoidectomy between 2016 and 2022 were retrospectively evaluated and divided into two groups: EEA™ (EEA) or Tri-Staple™ (Tri-EEA). The groups were matched for age, sex, American Society of Anesthesiologists (ASA), and neoadjuvant radiotherapy using propensity score matching (PSM). RESULT: Three hundred and thirty-six patients were included (228 EEA; 108 Tri-EEA). The groups were similar in sex, age, and neoadjuvant therapy. The Tri-EEA group had fewer patients with ASA III/IV scores (7% vs. 33%; p < 0.001). The Tri-EEA group had a lower incidence of leakage (4% vs. 11%; p = 0.023), reoperations (4% vs. 12%; p = 0.016), and severe complications (6% vs. 14%; p = 0.026). There was no difference in complications, mortality, readmission, and length of stay. After PSM, 108 patients in the EEA group were compared with 108 in the Tri-EEA group. The covariates sex, age, neoadjuvant radiotherapy, and ASA were balanced, and the risk of leakage (4% vs. 12%; p = 0.04), reoperation (4% vs. 14%; p = 0.014), and severe complications (6% vs. 15%; p = 0.041) remained lower in the Tri-EEA group. CONCLUSION: Tri-Staple™ reduces the risk of leakage in colorectal anastomosis. However, this study provides only insights, and further research is warranted to confirm these findings.

Evolution of therapy for locally advanced rectal cancer.

Rectal cancer is a prevalent disease worldwide. The standard treatment of locally advanced rectal cancer (LARC) is preoperative chemoradiotherapy followed by surgery and adjuvant systemic chemotherapy. Studies have been done to determine the best sequence of treatments to improve survival, cure rate and long term toxicity profile. In this paper, we will review the literature regarding the evolution of LARC treatment.

Robot-assisted transanal minimally invasive surgery for the treatment of rectal adenocarcinoma.

This is a video vignette of a 57-year-old asymptomatic female patient. The patient underwent a screening colonoscopy which revealed a 10 mm scar in the rectum. Biopsy resulted in a well-differentiated tubular adenocarcinoma. Computed tomography and pelvic magnetic resonance imaging confirmed tumor characteristics without distant or lymph nodal metastasis. A minimally invasive robotic transanal resection using the Da Vinci Xi platform was performed, achieving full-thickness lesion excision with uneventful recovery. Histopathology revealed intramucosal adenocarcinoma with free margins. Local resection is advocated for selected T1 lesions and demands a thorough preoperative assessment. Robotic-assisted surgery presents a valuable alternative for early rectal adenocarcinoma management.

From burden to relief: The economic and quality-of-life advantages of pseudo continent perineal colostomy in ultra-low rectal cancer patients.

BACKGROUND AND OBJECTIVE: Pseudo Continent Perineal Colostomy (PCPC) is an alternative technique to left iliac colostomy (LIC) after abdominoperineal resection for ultra low rectal cancer (ULRC). It allows placing the stoma in the perineum to preserve patients' body image. However, concerns about its impact on quality of life and management costs have limited its adoption. We aimed to compare the early outcomes and financial burden of PCPC and LIC in ULRC patients in Morocco, a low-middle-income country. METHODS: From January 2018 to December 2019, all patients who underwent abdomino-perineal resection (APR) with LIC or PCPC were prospectively enrolled. For each patient, baseline characteristics, and in hospital and 90 days morbidity with a focus on perineal complications were reported. Quality of life (QOL) was assessed using the validated EORTC-C30 and CR29 questionnaires. Financial burden to patients was reported using declarative out-of-pocket costs (OOPC) analysis. RESULTS: Among 49 patients who underwent APR, 33 received PCPC and 16 received definitive LIC. Similar rates of early perineal complications were observed between the two groups (p = 0.49). Readmission rate at POD90 was higher in the LIC-group due to perineal sepsis (p = 0.09). QOL analysis at 6 months revealed that patients with PCPC had a higher global health status (p = 0.006), a better physical functioning and reported fewer symptoms of flatulence and fecal incontinence (p = 0.001). Patients with a LIC reported more financial difficulties with higher median OOPC of stoma management up to €23 versus €0 per month for PCPC (p = 0.0024). PCPC was the only predictive factor of improved patient reported outcomes. CONCLUSIONS: PCPC is a cost-effective alternative to the standard definitive colostomy without alteration of the QOL or additional perineal complications during the first 6 months following the surgery. These findings may help convince surgeons to offer this option to patients refusing definitive LIC.

Low energy contact X-ray brachytherapy for treatment of rectal cancer: a health technology appraisal by Health Technology Wales.

AIM: Health Technology Wales sought to evaluate the clinical and cost-effectiveness of contact X-ray brachytherapy (CXB) for early-stage rectal cancer. METHODS: Relevant studies were identified through systematic searches of MEDLINE, Embase, Cochrane Library and Scopus. A cost-utility model was developed to estimate the cost-effectiveness of CXB in National Health Service Wales, using results of the Organ Preservation in Early Rectal Adenocarcinoma (OPERA) trial. Patient perspectives were obtained through the Papillon Patient Support group and All-Wales Cancer Network. RESULTS: The OPERA randomized controlled trial showed that CXB improved complete response and organ preservation rates compared with external-beam boost for people with T2-3b, N0-1, M0 rectal cancer who are fit for surgery. Managing more of this population non-operatively after CXB was estimated to provide 0.2 quality-adjusted life years at an additional cost of £887 per person. CXB was cost effective compared with external-beam boost at a cost of £4463 per quality-adjusted life year gained. This conclusion did not change in scenario analysis and CXB was cost effective in 91% of probabilistic sensitivity analyses. Patients valued receiving clear information on all available options to support their individual treatment choices. The detrimental impact of a stoma on quality of life led some patients to reject the idea that surgery was their only option. CONCLUSION: This evidence review and cost-utility analysis indicates that CXB is likely to be clinically and cost effective, as part of a watch and wait strategy for adults fit for surgery. Wider access to CXB is supported by patient testimonies.

Turnbull-Cutait pull-through coloanal anastomosis versus standard coloanal anastomosis plus diverting ileostomy for low anterior resection: a meta-analysis and systematic review.

PURPOSE: Coloanal anastomosis with loop diverting ileostomy (CAA) is an option for low anterior resection of the rectum, and Turnbull-Cutait coloanal anastomosis (TCA) regained popularity in the effort to offer patients a reconstructive option. In this context, we aimed to compare both techniques. METHODS: PubMed, Cochrane, and Scopus were searched for studies published until January 2024. Odds ratios (RRs) with 95% confidence intervals (CIs) were pooled with a random-effects model. Statistical significance was defined as p < 0.05. Heterogeneity was assessed using the Cochran Q test and I2 statistics, with p-values inferior to 0.10 and I2 >25% considered significant. Statistical analysis was conducted in RStudio version 4.1.2 (R Foundation for Statistical Computing). Registered number CRD42024509963. RESULTS: One randomized controlled trial and nine observational studies were included, comprising 1,743 patients, of whom 899 (51.5%) were submitted to TCA and 844 (48.5%) to CAA. Most patients had rectal cancer (52.2%), followed by megacolon secondary to Chagas disease (32.5%). TCA was associated with increased colon ischemia (OR 3.54; 95% CI 1.13 to 11.14; p < 0.031; I2 = 0%). There were no differences in postoperative complications classified as Clavien-Dindo ≥ IIIb, anastomotic leak, pelvic abscess, intestinal obstruction, bleeding, permanent stoma, or anastomotic stricture. In subgroup analysis of patients with cancer, TCA was associated with a reduction in anastomotic leak (OR 0.55; 95% CI 0.31 to 0.97 p = 0.04; I2 = 34%). CONCLUSION: TCA was associated with a decrease in anastomotic leak rate in subgroups analysis of patients with cancer.

Comparison of hand-sewn anterior repair, resection and hand-sewn anastomosis, resection and stapled anastomosis techniques for the reversal of diverting loop ileostomy after low anterior rectal resection: a randomized clinical trial.

BACKGROUND: Low anterior resection in patients with rectal cancer may require a defunctioning loop ileostomy formation that requires closure after a period of time. There are three common techniques for ileostomy closure: anterior repair (AR or fold-over closure), resection and hand-sewn anastomosis (RHA), and resection and stapled anastomosis (RSA). We aimed to compare them on the basis of operative and postoperative features. METHODS: Patients with rectal cancer who underwent low anterior resection without complications were included in this study and randomly assigned to three parallel groups to undergo loop ileostomy closure via either AR, RHA, or RSA. Early and late outcomes were gathered from all included patients. RESULTS: Among 93 patients with a mean age of 56.21 ± 11.78 years, consisting of 58 (62.4%) men, 31 patients underwent AR, 30 patients RHA, and 32 patients RSA. There was no significant difference among the groups regarding the frequency and location of intraoperative injuries (P = 0.157). The AR groups demonstrated significantly less consumption of gauzes following intraoperative bleeding compared to the two others groups. The results showed that the duration of surgery in the RSA was significantly shorter than in the AR or RHA group (both P < 0.001). Regarding postoperative course, only one case of hematoma and two cases of surgical wound infection occurred in the RHA group. Anastomotic leakage and complete or partial obstruction did not occur in any group of patients. Latent postoperative complications did not occur in any group of patients. The median time between surgery and discharge as well as the interval until first gas passage, first defecation, oral tolerated liquid diet, as well as oral tolerated soft and regular diet in the AR group were significantly lower than in the two other groups (both P < 0.001). However, there was no statistical difference in these intervals between the RHA and RSA groups. CONCLUSIONS: Resection and stapled anastomosis had the shortest duration among the three techniques; however, anterior repair had faster recovery, including earlier tolerated oral diet, gas passing and defecation, and discharge, in comparison with the other techniques. TRIAL REGISTRATION: Trial registration number IRCT20120129008861N5.

The importance of preoperative T3 stage substaging by 3D endorectal ultrasonography for the prognosis of middle and low rectal cancer.

OBJECTIVE: The study aimed to validate the role of 3D-endorectal ultrasonography in prognosis and recurrence for patients with T3-stage rectal cancer by evaluating the preoperative extramural depth of tumor invasion. METHODS: In this study, we investigated the medical records of rectal cancer patients who were admitted to Changhai Hospital's Colorectal Surgery Division. The sample group was categorized into three subgroups (T3a, T3b, and T3c) based on the extent of tumor progression (<5 mm, 5-10 mm, and >10 mm) to assess the endorectal ultrasonography diagnostic performance. The 5-year disease-free survival and overall survival were assessed using the Kaplan-Meier method and a log rank test. Cox regression analysis verified the tumor invasion depth's significance as a prognostic predictor, and it was also utilized to evaluate other independent risk variables for recurrence after surgery. RESULTS: The study included 72 individuals with low and middle rectal cancer from January 2014 to November 2019. Twenty-two individuals had stage T3a, 22 had stage T3b, and 28 had stage T3c based on preoperative endorectal ultrasonography. Endorectal ultrasonography had 88.0%, 86.8%, and 76.2% overall accuracy for stratifying subgroups, respectively. According to the Kaplan-Meier curve, 5-year OS was 100%, 83.5%, and 92.9% for T3a, T3b, and T3c (p = 0.172), and 5-year disease-free survival was 100%, 80.8%, and 72.9% for T3a, T3b, and T3c, respectively (p = 0.014). A distinct risk factor for 5-year disease-free survival was the degree of tumor infiltration (p = 0.039). CONCLUSION: Preoperative T3 stage subdivision allows for categorization of prognosis and survival. Endorectal ultrasonography reports should make explicit declarations of T3a, T3b, and T3c scales.

Image-based artificial intelligence for the prediction of pathological complete response to neoadjuvant chemoradiotherapy in patients with rectal cancer: a systematic review and meta-analysis.

OBJECTIVE: Artificial intelligence (AI) holds enormous potential for noninvasively identifying patients with rectal cancer who could achieve pathological complete response (pCR) following neoadjuvant chemoradiotherapy (nCRT). We aimed to conduct a meta-analysis to summarize the diagnostic performance of image-based AI models for predicting pCR to nCRT in patients with rectal cancer. METHODS: This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A literature search of PubMed, Embase, Cochrane Library, and Web of Science was performed from inception to July 29, 2023. Studies that developed or utilized AI models for predicting pCR to nCRT in rectal cancer from medical images were included. The Quality Assessment of Diagnostic Accuracy Studies-AI was used to appraise the methodological quality of the studies. The bivariate random-effects model was used to summarize the individual sensitivities, specificities, and areas-under-the-curve (AUCs). Subgroup and meta-regression analyses were conducted to identify potential sources of heterogeneity. Protocol for this study was registered with PROSPERO (CRD42022382374). RESULTS: Thirty-four studies (9933 patients) were identified. Pooled estimates of sensitivity, specificity, and AUC of AI models for pCR prediction were 82% (95% CI: 76-87%), 84% (95% CI: 79-88%), and 90% (95% CI: 87-92%), respectively. Higher specificity was seen for the Asian population, low risk of bias, and deep-learning, compared with the non-Asian population, high risk of bias, and radiomics (all P < 0.05). Single-center had a higher sensitivity than multi-center (P = 0.001). The retrospective design had lower sensitivity (P = 0.012) but higher specificity (P < 0.001) than the prospective design. MRI showed higher sensitivity (P = 0.001) but lower specificity (P = 0.044) than non-MRI. The sensitivity and specificity of internal validation were higher than those of external validation (both P = 0.005). CONCLUSIONS: Image-based AI models exhibited favorable performance for predicting pCR to nCRT in rectal cancer. However, further clinical trials are warranted to verify the findings.

Adaptive Individualized high-dose preoperAtive (AIDA) chemoradiation in high-risk rectal cancer: a phase II trial.

PURPOSE: To evaluate the pathological complete response (pCR) rate of locally advanced rectal cancer (LARC) after adaptive high-dose neoadjuvant chemoradiation (CRT) based on 18 F-fluorodeoxyglucose positron emission tomography/computed tomography (18 F-FDG-PET/CT). METHODS: The primary endpoint was the pCR rate. Secondary endpoints were the predictive value of 18 F-FDG-PET/CT on pathological response and acute and late toxicity. All patients performed 18 F-FDG-PET/CT at baseline (PET0) and after 2 weeks during CRT (PET1). The metabolic PET parameters were calculated both at the PET0 and PET1. The total CRT dose was 45 Gy to the pelvic lymph nodes and 50 Gy to the primary tumor, corresponding mesorectum, and to metastatic lymph nodes. Furthermore, a sequential boost was delivered to a biological target volume defined by PET1 with an additional dose of 5 Gy in 2 fractions. Capecitabine (825 mg/m2 twice daily orally) was prescribed for the entire treatment duration. RESULTS: Eighteen patients (13 males, 5 females; median age 55 years [range, 41-77 years]) were enrolled in the trial. Patients underwent surgical resection at 8-9 weeks after the end of neoadjuvant CRT. No patient showed grade > 1 acute radiation-induced toxicity. Seven patients (38.8%) had TRG = 0 (complete regression), 5 (27.0%) showed TRG = 2, and 6 (33.0%) had TRG = 3. Based on the TRG results, patients were classified in two groups: TRG = 0 (pCR) and TRG = 1, 2, 3 (non pCR). Accepting p < 0.05 as the level of significance, at the Kruskal-Wallis test, the medians of baseline-MTV, interim-SUVmax, interim-SUVmean, interim-MTV, interim-TLG, and the MTV reduction were significantly different between the two groups. 18 F-FDG-PET/CT was able to predict the pCR in 77.8% of cases through compared evaluation of both baseline PET/CT and interim PET/CT. CONCLUSIONS: Our results showed that a dose escalation on a reduced target in the final phase of CRT is well tolerated and able to provide a high pCR rate.

Development and multicenter validation of a multiparametric imaging model to predict treatment response in rectal cancer.

OBJECTIVES: To develop and validate a multiparametric model to predict neoadjuvant treatment response in rectal cancer at baseline using a heterogeneous multicenter MRI dataset. METHODS: Baseline staging MRIs (T2W (T2-weighted)-MRI, diffusion-weighted imaging (DWI) / apparent diffusion coefficient (ADC)) of 509 patients (9 centres) treated with neoadjuvant chemoradiotherapy (CRT) were collected. Response was defined as (1) complete versus incomplete response, or (2) good (Mandard tumor regression grade (TRG) 1-2) versus poor response (TRG3-5). Prediction models were developed using combinations of the following variable groups: (1) Non-imaging: age/sex/tumor-location/tumor-morphology/CRT-surgery interval (2) Basic staging: cT-stage/cN-stage/mesorectal fascia involvement, derived from (2a) original staging reports, or (2b) expert re-evaluation (3) Advanced staging: variables from 2b combined with cTN-substaging/invasion depth/extramural vascular invasion/tumor length (4) Quantitative imaging: tumour volume + first-order histogram features (from T2W-MRI and DWI/ADC) Models were developed with data from 6 centers (n = 412) using logistic regression with the Least Absolute Shrinkage and Selector Operator (LASSO) feature selection, internally validated using repeated (n = 100) random hold-out validation, and externally validated using data from 3 centers (n = 97). RESULTS: After external validation, the best model (including non-imaging and advanced staging variables) achieved an area under the curve of 0.60 (95%CI=0.48-0.72) to predict complete response and 0.65 (95%CI=0.53-0.76) to predict a good response. Quantitative variables did not improve model performance. Basic staging variables consistently achieved lower performance compared to advanced staging variables. CONCLUSIONS: Overall model performance was moderate. Best results were obtained using advanced staging variables, highlighting the importance of good-quality staging according to current guidelines. Quantitative imaging features had no added value (in this heterogeneous dataset). CLINICAL RELEVANCE STATEMENT: Predicting tumour response at baseline could aid in tailoring neoadjuvant therapies for rectal cancer. This study shows that image-based prediction models are promising, though are negatively affected by variations in staging quality and MRI acquisition, urging the need for harmonization. KEY POINTS: This multicenter study combining clinical information and features derived from MRI rendered disappointing performance to predict response to neoadjuvant treatment in rectal cancer. Best results were obtained with the combination of clinical baseline information and state-of-the-art image-based staging variables, highlighting the importance of good quality staging according to current guidelines and staging templates. No added value was found for quantitative imaging features in this multicenter retrospective study. This is likely related to acquisition variations, which is a major problem for feature reproducibility and thus model generalizability.

MRI-based multiregional radiomics for preoperative prediction of tumor deposit and prognosis in resectable rectal cancer: a bicenter study.

OBJECTIVE: To build T2WI-based multiregional radiomics for predicting tumor deposit (TD) and prognosis in patients with resectable rectal cancer. MATERIALS AND METHODS: A total of 208 patients with pathologically confirmed rectal cancer from two hospitals were prospectively enrolled. Intra- and peritumoral features were extracted separately from T2WI images and the least absolute shrinkage and selection operator was used to screen the most valuable radiomics features. Clinical-radiomics nomogram was developed by radiomics signatures and the most predictive clinical parameters. Prognostic model for 3-year recurrence-free survival (RFS) was constructed using univariate and multivariate Cox analysis. RESULTS: For TD, the area under the receiver operating characteristic curve (AUC) for intratumoral radiomics model was 0.956, 0.823, and 0.860 in the training cohort, test cohort, and external validation cohort, respectively. AUC for the peritumoral radiomics model was 0.929, 0.906, and 0.773 in the training cohort, test cohort, and external validation cohort, respectively. The AUC for combined intra- and peritumoral radiomics model was 0.976, 0.918, and 0.874 in the training cohort, test cohort, and external validation cohort, respectively. The AUC for clinical-radiomics nomogram was 0.989, 0.777, and 0.870 in the training cohort, test cohort, and external validation cohort, respectively. The prognostic model constructed by combining intra- and peritumoral radiomics signature score (radscore)-based TD and MRI-reported lymph nodes metastasis (LNM) indicated good performance for predicting 3-year RFS, with AUC of 0.824, 0.865, and 0.738 in the training cohort, test cohort and external validation cohort, respectively. CONCLUSION: Combined intra- and peritumoral radiomics model showed good performance for predicting TD. Combining intra- and peritumoral radscore-based TD and MRI-reported LNM indicated the recurrence risk. CLINICAL RELEVANCE STATEMENT: Combined intra- and peritumoral radiomics model could help accurately predict tumor deposits. Combining this predictive model-based tumor deposits with MRI-reported lymph node metastasis was associated with relapse risk of rectal cancer after surgery. KEY POINTS: • Combined intra- and peritumoral radiomics model provided better diagnostic performance than that of intratumoral and peritumoral radiomics model alone for predicting TD in rectal cancer. • The predictive performance of the clinical-radiomics nomogram was not improved compared with the combined intra- and peritumoral radiomics model for predicting TD. • The prognostic model constructed by combining intra- and peritumoral radscore-based TD and MRI-reported LNM showed good performance for assessing 3-year RFS.

High-resolution integrated dynamic shimming diffusion-weighted imaging (DWI) in the assessment of rectal cancer.

OBJECTIVES: To investigate the feasibility of high-resolution integrated dynamic shimming echo planar imaging (iEPI) applied to rectal cancer. METHODS: A total of seventy-eight patients with non-mucinous rectum adenocarcinoma were enrolled in this study. Using a prototype high-resolution iEPI sequence, high-resolution single-shot EPI (sEPI) sequence, and sEPI sequence, subjective and objective assessment and apparent diffusion coefficient (ADC) value were measured for comparison. The spearman rank correlation analysis test and the receiver operating characteristic curve were performed to evaluate correlation between tumor ADC values, corresponding T stage, and differentiation degree of rectal cancer. RESULTS: The subjective assessment of the image quality (IQ) of high-resolution iEPI was rated superior to high-resolution sEPI and sEPI by both readers (p < 0.001). Signal-to-noise ratio, contrast-to-noise, and signal-intensity ratio were significantly higher in high-resolution iEPI than the other two sequences (p < 0.001). There was no significant difference of tumor ADC values among three EPI sequences in the group of low- to well-differentiated rectal cancer. An inverse correlation was noted between ADC values on three DWI sequences and pathological T stage of rectal cancer (r = - 0.693, - 0.689, - 0.640, p < 0.001). The AUC values of high-resolution iEPI, high-resolution sEPI, and sEPI in predicting well-differentiated rectal cancer were 0.910, 0.761, and 0.725 respectively. CONCLUSIONS: In conclusion, the high-resolution iEPI provided significantly higher IQ and stable ADC compared to another two sequences. High-resolution iEPI has the highest efficacy among three examined sequences in differentiation of rectal cancer with different degrees of differentiation. KEY POINTS: • High-resolution iEPI provided a significantly better IQ than high-resolution sEPI and sEPI when assessing rectal cancer. • The AUC of high-resolution sEPI was the highest among three EPI sequences in predicting well-differentiated rectal cancer.

Extracellular volume fraction determined by equilibrium contrast-enhanced CT for the prediction of the pathological complete response to neoadjuvant chemoradiotherapy for locally advanced rectal cancer.

OBJECTIVES: To determine the extracellular volume (ECV) fraction derived from equilibrium contrast-enhanced CT for predicting pathological complete response (pCR) after neoadjuvant chemoradiotherapy (NCRT) in locally advanced rectal cancer (LARC). METHODS: The ECV fraction before NCRT (ECVpre) and/or ECV after NCRT (ECVpost) of rectal tumors was assessed, and ECVΔ was calculated as ECVpost - ECVpre. The histopathologic tumor regression grading (TRG) was assessed. pCR (TRG 0 grade) was defined as the absence of viable tumor cells in the primary tumor and lymph nodes. Demographic and clinicopathological characteristics and ECV fraction were compared between the pCR and non-pCR groups. A mixed model was constructed by logistic regression. The performance for predicting pCR was assessed with the area under the receiver-operator curve (AUC). The AUCs of the different methods were compared by the method proposed by DeLong et al. RESULTS: Seventy-five patients were included; 17 achieved pCR, and 58 achieved non-pCR. The ECVpost (17.05 ± 2.36% vs. 29.94 ± 1.20%; p < 0.001) and ECVΔ (- 17.01 ± 3.01% vs. 0.44 ± 1.45%; p < 0.001) values in the pCR group were significantly lower than those in the non-pCR group. The mixed model that combined ECVpost with ECVΔ achieved an AUC of 0.92 (95% confidence interval (CI) = 0.81-0.98), which was higher than that of ECVpost (AUC, 0.91 (95% CI = 0.80-0.97); p = 0.60) or ECVΔ (AUC, 0.90 (95% CI = 0.79-0.97); p = 0.61). CONCLUSIONS: ECVpost and ECVΔ determined by using equilibrium contrast-enhanced CT were useful in distinguishing between pCR and non-pCR patients with LARC who received NCRT. KEY POINTS: • ECVpost and ECVΔ (ECVpost - ECVpre) differed significantly between the non-pCR and pCR groups. • ECVpre cannot be used to predict the efficacy of neoadjuvant chemoradiotherapy. • ECVpost combined with ECVΔ had the best performance with an AUC of 0.92 for predicting pCR after NCRT in LARC.

Comparison of MRI response evaluation methods in rectal cancer: a multicentre and multireader validation study.

OBJECTIVES: To compare four previously published methods for rectal tumor response evaluation after chemoradiotherapy on MRI. METHODS: Twenty-two radiologists (5 rectal MRI experts, 17 general/abdominal radiologists) retrospectively reviewed the post-chemoradiotherapy MRIs of 90 patients, scanned at 10 centers (with non-standardized protocols). They applied four response methods; two based on T2W-MRI only (MRI tumor regression grade (mrTRG); split-scar sign), and two based on T2W-MRI+DWI (modified-mrTRG; DWI-patterns). Image quality was graded using a 0-6-point score (including slice thickness and in-plane resolution; sequence angulation; DWI b-values, signal-to-noise, and artefacts); scores < 4 were classified below average. Mixed model linear regression was used to calculate average sensitivity/specificity/accuracy to predict a complete response (versus residual tumor) and assess the impact of reader experience and image quality. Group interobserver agreement (IOA) was calculated using Krippendorff's alpha. Readers were asked to indicate their preferred scoring method(s). RESULTS: Average sensitivity/specificity/accuracy was 57%/64%/62% (mrTRG), 36%/79%/66% (split-scar), 40%/79%/67% (modified-mrTRG), and 37%/82%/68% (DWI-patterns); mrTRG showed higher sensitivity but lower specificity and accuracy (p < 0.001) compared to the other methods. IOA was lower for the split scar method (0.18 vs. 0.39-0.43). Higher reader experience had a significant positive effect on diagnostic performance and IOA (except for the split scar sign); below-average imaging quality had a significant negative effect on diagnostic performance. DWI pattern was selected as the preferred method by 73% of readers. CONCLUSIONS: Methods incorporating DWI showed the most favorable results when combining diagnostic performance, IOA, and reader preference. Reader experience and image quality clearly impacted diagnostic performance emphasizing the need for state-of-the-art imaging and dedicated radiologist training. KEY POINTS: • In a multireader study comparing 4 MRI methods for rectal tumor response evaluation, those incorporating DWI showed the best results when combining diagnostic performance, IOA, and reader preference. • The most preferred method (by 73% of readers) was the "DWI patterns" approach with an accuracy of 68%, high specificity of 82%, and group IOA of 0.43. • Reader experience level and MRI quality had an evident effect on diagnostic performance and IOA.

Prognostic value of multi b-value DWI in patients with locally advanced rectal cancer.

OBJECTIVES: To evaluate the potential of multi b-value DWI in predicting the prognosis of patients with locally advanced rectal cancer (LARC). METHODS: From 2015 to 2019, a total of 161 patients with LARC were enrolled and randomly sampled into a training set (n = 113) and validation set (n = 48). Multi b-value DWI (b = 0~1500 s/mm2) scans were postprocessed to generate functional parameters, including apparent diffusion coefficient (ADC), Dt, Dp, f, distributed diffusion coefficient (DDC), and α. Histogram features of each functional parameter were submitted into Least absolute shrinkage and selection operator (LASSO) and stepwise multivariate COX analysis to generate DWI_score based on the training set. The prognostic model was constructed with functional parameter, DWI_score, and clinicopathologic factors by using univariate and multivariate COX analysis on the training set and verified on the validation set. RESULTS: Multivariate COX analysis revealed that DWI_score was an independent indicator for 5-year progression-free survival (PFS, HR = 5.573, p < 0.001), but not for overall survival (OS, HR = 2.177, p = 0.051). No mean value of functional parameters was correlated with PFS or OS. Prognostic model for 5-year PFS based on DWI_score, TNM-stage, mesorectal fascia (MRF), and extramural venous invasion (EMVI) showed good performance both in the training set (AUC = 0.819) and validation set (AUC = 0.815). CONCLUSIONS: The DWI_score based on histogram features of multi b-value DWI functional parameters was an independent factor for PFS of LARC and the prognostic model with a combination of DWI_score and clinicopathologic factors could indicate the progression risk before treatment. KEY POINTS: • Mean value of functional parameters obtained from multi b-value DWI might not be useful to assess the prognosis of LARC. • The DWI_score based on histogram features of multi b-value DWI functional parameters was an independent prognosis factor for PFS of LARC. • Prognostic model based on DWI_score and clinicopathologic factors could indicate the progression risk of LARC before treatment.