Nuclear localization of Argonaute 2 is affected by cell density and may relieve repression by microRNAs.

Argonaute protein is associated with post-transcriptional control of cytoplasmic gene expression through miRNA-induced silencing complexes (miRISC). Specific cellular and environmental conditions can trigger AGO protein to accumulate in the nucleus. Localization of AGO is central to understanding miRNA action, yet the consequences of AGO being in the nucleus are undefined. We show nuclear enrichment of AGO2 in HCT116 cells grown in two-dimensional culture to high density, HCT116 cells grown in three-dimensional tumor spheroid culture, and human colon tumors. The shift in localization of AGO2 from cytoplasm to nucleus de-represses cytoplasmic AGO2-eCLIP targets that were candidates for canonical regulation by miRISC. Constitutive nuclear localization of AGO2 using an engineered nuclear localization signal increases cell migration. Critical RNAi factors also affect the localization of AGO2. Knocking out an enzyme essential for miRNA biogenesis, DROSHA, depletes mature miRNAs and restricts AGO2 localization to the cytoplasm, while knocking out the miRISC scaffolding protein, TNRC6, results in nuclear localization of AGO2. These data suggest that AGO2 localization and miRNA activity can be regulated depending on environmental conditions, expression of mature miRNAs, and expression of miRISC cofactors. Localization and expression of core miRISC protein machinery should be considered when investigating the roles of miRNAs.

Effect of Hospital Cancer Designation on use of Multimodal Therapy and Survival of Metastatic Colorectal Cancer: A State-Wide Analysis.

BACKGROUND: Stage IV colorectal cancer (CRC) often requires multidisciplinary approach. However, multimodal treatment options (receipt of > 1 type of treatment) may not be uniformly delivered across health systems. We characterized the association between center-level cancer center designation and receipt of multimodal treatment and survival. METHODS: The Texas Cancer Registry was used to identify patients diagnosed with stage IV CRC from 2004-2017. We identified those who received care at either: a National Cancer Institute-designated (NCI-D), an American College of Surgeons-Commission on Cancer-designated (ACS-D), or an undesignated facility. We used multivariable logistic regression and Cox regression for analysis to assess receipt of one or more treatment modality and 5-year overall survival. RESULTS: Of 19,355 patients with stage IV CRC, 2955 (15%) received care at an NCI-D facility and 5871 (30%) received multimodal therapy. Both NCI-D (odds ratio [OR] 1.64; 95% confidence interval [CI] 1.49-1.81) and ACS-D (OR 1.37; 95% CI 1.27-1.48) were associated with increased likelihood of multimodal therapy compared with undesignated centers. NCI-D also was associated with significantly improved survival (hazard ratio [HR] 0.74; 95% CI 0.70-0.78), although ACS-D was associated with a modest improvement in survival (HR 0.95; 95% CI 0.92-0.99). Receipt of multimodal therapy was strongly associated with improved survival (HR 0.61; 95% CI 0.59-0.63). CONCLUSIONS: In patients with stage IV CRC, treatment at ACS-D and NCI-D facilities was associated with increased use of multimodality therapy and improved survival. However, only a small proportion of patients have access to these specialized centers, highlighting a need for expanded access to multimodal therapies at other centers.

Defining Volume Targets for Regionalization of Pancreaticoduodenectomy, Esophagectomy, and Major Lung Resection Centers to Improve Oncologic and Surgical Outcomes.

BACKGROUND: Performance of complex cancer surgeries at high-volume (HV) centers has been shown to reduce operative mortality. However, the case volume threshold that should be used to define HV centers is unknown. In this study, we determined thresholds to define HV pancreaticoduodenectomy, esophagectomy, and major lung resection centers based on clinical parameters. Then, we assessed the association of hospital volume with oncologic outcomes and overall survival. METHODS: We identified adult NCDB patients undergoing pancreaticoduodenectomy, esophagectomy, and major lung resections between 2004 and 2015. Multivariable models with restricted cubic splines were built to predict 5-year overall survival for each surgery group according to average yearly case volume, adjusting for demographic and clinicopathologic factors. The change point procedure was then used to identify volume cut-points for each surgery type. RESULTS: We identified the following thresholds to define HV status: 25 cases/year for pancreaticoduodenectomy; 18 cases/year for esophagectomy; and 54 cases/year for major lung resections. For all surgery types, treatment at a HV center was associated with an increased likelihood of R0 resection and adequate lymph node evaluation. HV centers had significantly decreased 30- and 90-day, postoperative mortality after adjusting for age, sex, race, comorbidities, histology, and stage. An overall survival benefit also was observed for patients undergoing resections at HV centers. CONCLUSIONS: Using novel methodology, our study identified volume thresholds for HV pancreaticoduodenectomy, esophagectomy, and major lung resection centers that were associated with improved oncologic outcomes and overall survival. These definitions of HV centers should be considered when evaluating regionalization of complex cancer care.

Cost Analysis and Financial Implications of a Peritoneal Surface Malignancy Program in the USA.

BACKGROUND: We aimed to describe the financial implications of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) in the USA. MATERIALS AND METHODS: We conducted a retrospective cost analysis of 100 CRS/HIPEC procedures to examine the impact of patient and procedural factors on hospital costs and reimbursement. A comparison of surgeons' work relative value units (wRVUs) between CRS/HIPEC and a representative sample of complex surgical oncology procedures was made to assess the physicians' compensation rate. Univariable and multivariable backward logistic regression was used to analyze the association between perioperative variables and high direct cost (HDCs). RESULTS: The median direct cost per CRS/HIPEC procedure was US $44,770. The median hospital reimbursement was US $43,066, while professional reimbursement was US $8608, resulting in a positive contribution margin of US $7493/procedure. However, the contribution margin significantly varied with the payer mix. Privately insured patients had a positive median contribution margin of US $23,033, whereas Medicare-insured patients had a negative contribution margin of US $13,034. Length of stay (LOS) had the most significant association with HDC, and major complications had the most significant association with LOS. Finally, CRS/HIPEC procedures generated a median of 13 wRVU/h, which is significantly lower than the wRVU/h generated by open pancreatoduodenectomies, open gastrectomies, and hepatectomies. However, higher operation complexity and multiple visceral resections help compensate for the relatively low wRVU/h. CONCLUSIONS: CRS/HIPEC is an expensive operation, and prolonged LOS has the most significant impact on the total cost of the procedure. High-quality care is essential to improve patient outcomes and maintain the economic sustainability of the procedure.

Rates and Patterns of Recurrence After Microwave Ablation of Colorectal Liver Metastases: A Per Lesion Analysis of 416 Tumors in the Era of 2.45 GHz Generators.

BACKGROUND: For some patients with colorectal liver metastases (CRLMs), surgical resection of all visible disease can lead to long-term survival and even cure. When complete resection is not feasible, microwave ablation (MWA) can help achieve hepatic disease control. As modern 2.45-GHz MWA generators gain popularity, the characteristics of tumors most likely to benefit from this method remain unclear. This study aimed to evaluate local recurrence (LR) rates, patterns of recurrence, and factors contributing to treatment failure after 2.45-GHz MWA of CRLM. METHODS: Patients with CRLM who underwent operative 2.45-GHz MWA between 2011 and 2019 were identified in a prospectively maintained single-institution database. Recurrence outcomes were ascertained for each lesion by imaging review. Factors associated with LR were analyzed. RESULTS: The study enrolled 184 patients bearing 416 ablated tumors. Most of the patients (65.8%) had high clinical risk scores (3-5), and 165 (90%) underwent concurrent liver resection. The median tumor size was 10 mm. After a median follow-up period of 28.8 months, LR was observed in 45 tumors, and the cumulative incidence of LR at 24 months was 10.9% (95% confidence interval [CI], 8.0-14.3%]. In 7%, LR was the first recurrence site, often combined with recurrence elsewhere. The cumulative incidence of LR at 24 months was 6.8% (95% CI 3.8-11.0%) for tumors 10 mm in size or smaller, 12.4% (95% CI 7.8-18.1%) for tumors 11 to 20 mm in size, and 30.2% (95% CI 14.2-48.0%) for tumors larger than 20 mm. In the multivariable analysis, tumors larger than 20 mm with a subcapsular location were significantly associated with increased LR risk. CONCLUSIONS: Treatment of CRLM with 2.45-GHz MWA offers excellent local control at 2 years and is most successful for small tumors deep within the parenchyma.

Perioperative outcomes of robotic and laparoscopic surgery for colorectal cancer: a propensity score-matched analysis.

BACKGROUND: Robotic colorectal surgery is becoming the preferred surgical approach for colorectal cancer (CRC). It offers several technical advantages over conventional laparoscopy that could improve patient outcomes. In this retrospective cohort study, we compared robotic and laparoscopic surgery for CRC using a national cohort of patients. METHODS: Using the colectomy-targeted ACS-NSQIP database (2015-2020), colorectal procedures for malignant etiologies were identified by CPT codes for right colectomy (RC), left colectomy (LC), and low anterior resection (LAR). Optimal pair matching was performed. "Textbook outcome" was defined as the absence of 30-day complications, readmission, or mortality and a length of stay < 5 days. RESULTS: We included 53,209 out of 139,759 patients screened for eligibility. Laparoscopic-to-robotic matching of 2:1 was performed for RC and LC, and 1:1 for LAR. The largest standardized mean difference was 0.048 after matching. Robotic surgery was associated with an increased rate of textbook outcomes compared to laparoscopy in RC and LC, but not in LAR (71% vs. 64% in RC, 75% vs. 68% in LC; p < 0.001). Robotic LAR was associated with increased major morbidity (7.1% vs. 5.8%; p = 0.012). For all three procedures, the mean conversion rate of robotic surgery was lower than laparoscopy (4.3% vs. 9.2%; p < 0.001), while the mean operative time was higher for robotic (225 min vs. 177 min; p < 0.001). CONCLUSIONS: Robotic surgery for CRC offers an advantage over conventional laparoscopy by improving textbook outcomes in RC and LC. This advantage was not found in robotic LAR, which also showed an increased risk of serious complications. The associations highlighted in our study should be considered in the discussion of the surgical management of patients with colorectal cancer.

Conditional Survival in Patients With Rectal Cancer and Complete Clinical Response Managed by Watch and Wait After Chemoradiation: Recurrence Risk Over Time.

OBJECTIVE: Analyze conditional recurrence-free survival (cRFS) for rectal cancer patients with complete clinical response (cCR) after neoadjuvant chemoradiation (nCRT) managed nonoperatively after each year without recurrence. SUMMARY BACKGROUND DATA: Select patients with cCR after nCRT have been managed nonoperatively. Risk factors for local recurrence, the need for prolonged follow-up, and the risk of recurrence over time are not well defined. METHODS: Retrospective review of patients with rectal cancer cT2-4N0-2M0 treated with nCRT. Mean follow-up was 64 months. Patients who achieved cCR were managed nonoperatively. cRFS was used to investigate the evolution of recurrence-odds, as patients remain recurrence-free after completion of nCRT. Three-year cRFS was estimated at "x" years after completion of nCRT based on the formula cRFS3 = RFS(x+3)/RFS(x). RESULTS: One hundred ninety-seven patients with cCR after nCRT were included. Overall survival and recurrence-free survival (RFS) at 5 years were 81.9% (95% CI 74.0%-87.6%) and 60.4% (95% CI 52.5%-67.4%) respectively. Using cRFS estimates, the probability of remaining disease-free for an additional 3 years if the patient survived without disease at 1, 3, and 5 years, was 77.4% (95% CI 68.8%-83.8%), 91.0% (95% CI 81.9%-95.7%), and 94.3% (95% CI 82.9%-98.2%), respectively. In contrast, actuarial RFS rates for similar intervals were 79.1% (95% CI 72.5%-84.2%), 64.2% (95% CI 56.5%-70.8%), and 60.4% (95% CI 52.5%-67.4%). After 2 years disease-free, 3 year cRFS became similar for T2 and T3 cancers. In contrast, patients undergoing extended nCRT became less likely to develop recurrences only after initial 2 years of successful organ-preservation. CONCLUSIONS: Conditional survival suggests that patients have significantly lower risks (≤10%) of developing recurrences after 2 years of achieving cCR following nCRT.

Comprehensive Complication Index Validates Improved Outcomes Over Time Despite Increased Complexity in 3707 Consecutive Hepatectomies.

OBJECTIVE: The aim of this study was to evaluate trends over time in perioperative outcomes for patients undergoing hepatectomy. BACKGROUND: As perioperative care and surgical technique for hepatectomy have improved, the indications for and complexity of liver resections have evolved. However, the resulting effect on the short-term outcomes over time has not been well described. METHODS: Consecutive patients undergoing hepatectomy during 1998 to 2015 at 1 institution were analyzed. Perioperative outcomes, including the comprehensive complication index (CCI), were compared between patients who underwent hepatectomy in the eras 1998 to 2003, 2004 to 2009, and 2010 to 2015. RESULTS: The study included 3707 hepatic resections. The number of hepatectomies increased in each era (794 in 1998 to 2003, 1402 in 2004 to 2009, and 1511 in 2010 to 2015). Technical complexity increased over time as evidenced by increases in the rates of major hepatectomy (20%, 23%, 30%, P < 0.0001), 2-stage hepatectomy (0%, 3%, 4%, P < 0.001), need for portal vein embolization (5%, 9%, 9%, P = 0.001), preoperative chemotherapy for colorectal liver metastases (70%, 82%, 89%, P < 0.001) and median operative time (180, 175, 225 minutes, P < 0.001). Significant decreases over time were observed in median blood loss (300, 250, 200 mL, P < 0.001), transfusion rate (19%, 15%, 5%, P < 0.001), median length of hospitalization (7, 7, 6 days, P < 0.001), rates of CCI ≥26.2 (20%, 22%, 16%, P < 0.001) and 90-day mortality (3.1%, 2.6%, 1.3%, P < 0.01). On multivariable analysis, hepatectomy in the most recent era 2010 to 2015 was associated with a lower incidence of CCI ≥26.2 (odds ratio 0.7, 95% confidence interval 0.6-0.8, P < 0.0001). CONCLUSION: Despite increases in complexity over an 18-year period, continued improvements in surgical technique and perioperative outcomes yielded a resultant decrease in CCI in the most current era.

Poly(ADP-Ribose) Polymerase Inhibition Sensitizes Colorectal Cancer-Initiating Cells to Chemotherapy.

Colorectal cancer (CRC) remains a leading killer in the U.S. with resistance to treatment as the largest hurdle to cure. Colorectal cancer-initiating cells (CICs) are a self-renewing tumor population that contribute to tumor relapse. Here, we report that patient-derived CICs display relative chemoresistance compared with differentiated progeny. In contrast, conventional cell lines failed model therapeutic resistance. CICs preferentially repaired chemotherapy-induced DNA breaks, prompting us to interrogate DNA damage pathways against which pharmacologic inhibitors have been developed. We found that CICs critically depended on the key single-strand break repair mediator, poly(ADP-ribose) polymerase (PARP), to survive treatment with standard-of-care chemotherapy. Small molecule PARP inhibitors (PARPi) sensitized CICs to chemotherapy and reduced chemotherapy-treated CIC viability, self-renewal, and DNA damage repair. Although PARPi monotherapy failed to kill CICs, combined PARPi therapy with chemotherapy attenuated tumor growth in vivo. Clinical significance of PARPi for CRC patients was supported by elevated PARP levels in colorectal tumors compared with normal colon, with further increases in metastases. Collectively, our results suggest that PARP inhibition serves as a point of fragility for CICs by augmenting therapeutic efficacy of chemotherapy. Stem Cells 2019;37:42-53.

Prognostic Implications of Pathological Response to Neoadjuvant Chemoradiation in Pathologic Stage III Rectal Cancer.

OBJECTIVE: To evaluate the independent prognostic ability of the American Joint Committee on Cancer (AJCC) tumor regression scores within pathologic stage II and III rectal cancers. BACKGROUND: Response to neoadjuvant chemoradiation (nCRT) has been debated as a biologic surrogate for tumor biology and prognosis in rectal cancer. AJCC regression scores have been shown to correlate with prognosis. METHODS: Patient demographics, tumor characteristics, and AJCC scores (0 = complete response; 1 = isolated tumor cells remaining; 2 = residual cancer outgrown by fibrosis; 3 = extensive residual cancer) were assessed from 545 rectal cancer patients treated by nCRT followed by surgery at a single institution. Patients were classified as responders (score 0-2) or nonresponders (score 3). Survival analyses were performed using Cox proportional hazards models. RESULTS: Of 545 cases, 123 and 182 were pathologic stage II and III, respectively. Median follow-up was 4.9 years. AJCC regression scores were not independently prognostic within stage II cancers. However, AJCC scores were strongly associated with prognosis within stage III cancers (nonresponse 5-year overall survival [OS] 27% vs 67%, P < 0.001). Stage III responders (N = 139, 76.4%) had similar outcomes to stage II (5-year OS 67% vs 74%, P = 0.89). Conversely, stage III nonresponders (N = 43, 23.6%) approached stage IV outcomes (5-year OS 27% vs 18%, P = 0.09). On multivariable analysis, nonresponse (hazard ratio 3.2, 95% confidence interval 1.7-6.2), along with positive margin, abdominoperineal resection, and no adjuvant chemotherapy administration were independently associated with worse OS. CONCLUSIONS: AJCC response score after nCRT is a novel prognostic factor in pathologic stage III rectal cancer and may guide surveillance and adjuvant therapy decisions.

Conditional Probability of Survival After Neoadjuvant Chemoradiation and Proctectomy for Rectal Cancer: What Matters and When.

BACKGROUND: Disease-free survival estimated from the time of surgery does not account for the changing likelihood of survival based on time already accrued. Conditional disease-free survival is defined as the probability of remaining disease free after reaching a specific time point without recurrence. OBJECTIVE: The purpose of this study was to evaluate conditional disease-free survival for patients with rectal cancer who were treated by proctectomy after neoadjuvant chemoradiation. DESIGN: Demographics, tumor characteristics, and tumor regression scores were assessed. Three-year conditional disease-free survival was estimated at x year after surgery based on the formula cDFS3 = DFS(x+3)/DFS(x), where DFS is disease-free survival and cDFS is conditional disease-free survival. Analyses were performed using Cox proportional hazards models. SETTING: The study was conducted at a single tertiary referral center. PATIENTS: A total of 545 patients with rectal cancer who were treated by neoadjuvant chemoradiation and curative intent surgery between 1992 and 2012 were included. MAIN OUTCOME MEASURES: Disease-free survival and conditional disease-free survival were measured. RESULTS: The median patient age was 57.5 years, and 28.4% were women. Median follow-up was 5.9 years. Disease-free survival at 1, 3, and 5 years was 89%, 71%, and 63%. The probability of remaining disease free for an additional 3 years for patients disease free at 1, 3, and 5 years was 75%, 83%, and 82%. Tumor regression, pathologic stage, margin status, differentiation, and procedure (low anterior versus abdominoperineal resection) were associated with disease-free survival on multivariable analysis (p < 0.05), but their relevance varied over time. R1 resection and differentiation were initially significant but not at 5 years. In contrast, tumor regression after neoadjuvant chemoradiation had a long-lasting impact on survival (at 5 y, conditional disease-free survival for an additional 3 y: 91%, 85%, 76%, and 71% for regression scores 0, 1, 2, and 3; p = 0.002). LIMITATIONS: This was a retrospective study over 20 years, with evolution in adjuvant therapies during this time. CONCLUSIONS: Conditional disease-free survival estimates improved over time, confirming that most patients will see a recurrence within the first few years. The impact of specific prognostic factors evolves variably over time. This information is useful to patients and providers and can help guide counseling and surveillance. See Video Abstract at http://links.lww.com/DCR/A771.

Mucinous Histology Signifies Poor Oncologic Outcome in Young Patients With Colorectal Cancer.

BACKGROUND: The incidence of colorectal cancer in the young (under age 40) is increasing, and this population has worse oncologic outcomes. Mucinous histology is a potential prognostic factor in colorectal cancer, but has not been evaluated specifically in young patients. OBJECTIVE: The objective of the study was to determine factors associated with poor outcome in young patients with colorectal cancer (≤40 years) and to determine relationships between mucinous histology and oncologic outcomes in this population. DESIGN: This is a retrospective study. SETTING: Patients from a single-institution tertiary care center were studied. PATIENTS: A total of 224 patients with colorectal cancer under 40 years of age diagnosed between 1990 and 2010 were included (mean age, 34.7 years; 51.3% female). 34 patients (15.2%) had mucinous histology. INTERVENTIONS(S): There were no interventions. MAIN OUTCOME MEASURES: Oncologic outcomes were analyzed according to the presence of mucinous histology. RESULTS: The mucinous and nonmucin colorectal cancer study populations were statistically similar in age, sex, tumor location, pathological stage, differentiation, and adjuvant chemotherapy use. Five-year disease-free survival was 29.1% versus 71.3% (p < 0.0001) and 5-year overall survival was 54.7% versus 80.3% (p < 0.0001) for mucinous and nonmucinous patients, respectively. Mucinous colorectal cancers recurred earlier at a median time of 36.4 months versus 94.2 months for nonmucin colorectal cancers (p < 0.001). On multivariate analysis, pathological stage (stage II HR, 3.61; 95% CI, 1.37-9.50; stage III HR, 5.27; 95% CI, 2.12-12.33), positive margins (HR, 1.95; 95% CI, 1.12-3.23), angiolymphatic invasion (HR, 2.15; 95% CI, 1.26-3.97), and mucinous histology (HR, 2.36; 95% CI, 1.44-3.96) were independently associated with worse disease-free and overall survival. LIMITATIONS: This is a retrospective study without genetic information. CONCLUSIONS: Mucinous histology is a negative prognostic factor in young patients with colorectal cancer. This is associated with early and high recurrence rates, despite use of standard neoadjuvant and adjuvant regimens. Physicians need to be aware of this association and potentially explore novel treatment options. See Video Abstract at http://links.lww.com/DCR/A575.

Simvastatin enhances radiation sensitivity of colorectal cancer cells.

INTRODUCTION: Neoadjuvant chemoradiation (CRT) for rectal cancer induces variable responses, and better response has been associated with improved oncologic outcomes. Our group has previously shown that the administration of HMG-CoA reductase inhibitors, commonly known as statins, is associated with improved response to neoadjuvant CRT in rectal cancer patients. The purpose of this study was to study the effects of simvastatin on colorectal cancer cells and explore its potential as a radiation-sensitizer in vitro. METHODS: Four colorectal cancer cell lines (SW480, DLD1, SW837, and HRT18) were used to test the effects of simvastatin alone, radiation alone, and combination therapy. Outcome measures included ATP-based cell viability, colony formation, and protein (immunoblot) assays. RESULTS: The combination of radiation and simvastatin inhibited colony formation and cell viability of all four CRC lines, to a greater degree than either treatment alone (p < 0.01). In addition, the effects of simvastatin in this combination therapy were dose dependent, with increased concentrations resulting in more potentiated inhibitory effects. The radiosensitizing effects of simvastatin on cell viability were negated by the presence of exogenous GGPP in the media. On protein analyses of irradiated cells, simvastatin treatment inhibited phosphorylation of ERK1/2, in a dose-dependent manner, while the total levels of ERK1/2 remained stable. In addition, the combined treatment resulted in increased levels of cleaved caspase 3, indicating greater apoptotic activity in the cells treated with radiation and simvastatin together. CONCLUSIONS: Treatment with simvastatin hindered CRC cell viability and enhanced radiation sensitivity in vitro. These effects were tied to the depletion of GGPP and the decreased phosphorylation of ERK1/2, suggesting a prominent role for the EGFR-RAS-ERK1/2 pathway, through which statin enhances radiation sensitivity.

Incidence, Patterns, and Predictors of Locoregional Recurrence in Colon Cancer.

BACKGROUND: Locoregional recurrence (LR) in colon cancer is uncommon but often incurable, while the factors associated with it are unclear. The purpose of this study was to identify patterns and predictors of LR after curative resection for colon cancer. METHODS: All patients who underwent colon cancer resection with curative intent between 1994 and 2008 at a tertiary referral center were identified from a prospectively maintained institutional database. The association of LR with clinicopathologic and treatment characteristics was determined using univariable and multivariable analyses. RESULTS: A total of 1397 patients were included with a median follow-up of 7.8 years; 635 (45%) were female, and the median age was 69 years. LR was detected in 61 (4.4%) patients. Median time to LR was 21 months. On multivariable analysis, the independent predictors of LR were disease stage [hazard ratio (HR) for Stage II 4.6, 95% confidence interval (CI) 1.05-19.9, HR for Stage III 10.8, 95% CI 2.6-45.8], bowel obstruction (HR 3.8, 95% CI 1.9-7.4), margin involvement (HR 4.1, 95% CI 1.9-8.6), lymphovascular invasion (HR 1.9, 95% CI 1.06-3.5), and local tumor invasion (fixation to another structure, perforation, or presence of associated fistula, HR 2.2, 95% CI 1.1-4.5). Adjuvant chemotherapy was not associated with reduced LR in patients with either Stage II or Stage III tumors. CONCLUSIONS: Adherence to oncologic surgical principles in colon cancer resection results in low rates of LR, which is associated with tumor-dependent factors. Recognition of these factors can help to determine appropriate postoperative surveillance.

Molecular Biology: Are We Getting Any Closer to Providing Clinically Useful Information?

Advances in molecular biology and biomarker research have significantly impacted our understanding and treatment of multiple solid malignancies. In rectal cancer, where neoadjuvant chemoradiation is widely used for locally advanced disease, most efforts have focused on the identification of predictors of response in an attempt to appropriately select patients for multimodality therapy. A variety of biomarkers have been studied, including genetic mutations, chromosomal copy number alterations, and single as well as multigene expression patterns. Also, as transanal resection of rectal tumors requires accurate preoperative detection of lymph node metastasis, the identification of biomarkers of regional nodal involvement has been another important field of active research. While preliminary results have been promising, lack of external validation means has a limited translation to clinical use. This review summarizes recent developments in rectal cancer biomarker research, highlighting the challenges associated with their adoption, and evaluating their potential for clinical use.

NPTX2 is associated with neoadjuvant therapy response in rectal cancer.

BACKGROUND: Neoadjuvant chemoradiation (CRT) is recommended for locally advanced rectal cancer. Tumor response varies from pathologic complete response (pCR) to no tumor regression. The mechanisms behind CRT resistance remain undefined. In our previously generated complementary DNA microarrays of pretreatment biopsies from rectal cancer patients, neuronal pentraxin 2 (NPTX2) expression discriminated patients with pCR from those with residual tumor. As tumor response is prognostic for survival, we sought to evaluate the clinical relevance of NPTX2 in rectal cancer. MATERIALS AND METHODS: Real-time quantitative polymerase chain reaction was used to evaluate NPTX2 messenger RNA expression in individual rectal cancers before CRT. Tumors with NPTX2 expression <50% of normal rectum were defined as NPTX2-low and those with >50% were defined as NPTX2-high. NPTX2 levels were compared to response to therapy and oncologic outcomes using Mann-Whitney, Kruskal-Wallis, chi-square, and Mantel-Cox (log-rank) tests, as appropriate. RESULTS: Rectal cancers from 40 patients were included. The mean patient age was 56.8 years, and 30% were female. pCR was achieved in eight of 40 patients (20%). In these patients, messenger RNA NPTX2 levels were significantly decreased compared to those with residual cancer (fold change 30.4, P = 0.017). Patients with NPTX2-low tumors (n = 13) achieved improved response to treatment (P = 0.012 versus NPXT2-high tumors), with 38.5% and 46.1% of patients achieving complete or moderate response, respectively. Of patients with NPTX2-high tumors (n = 27), 11.1% and 18.5% achieved complete or moderate response, respectively. No recurrence or death was recorded in patients with NPTX2-low tumors, reflecting more favorable disease-free survival (P = 0.045). CONCLUSIONS: Decreased NPTX2 expression in rectal adenocarcinomas is associated with improved response to CRT and improved prognosis. Further studies to validate these results and elucidate the biological role of NPTX2 in rectal cancer are needed.

Effect of KRAS Mutation on Long-Term Outcomes of Patients Undergoing Hepatic Resection for Colorectal Liver Metastases.

PURPOSE: To investigate the prognostic value of KRAS in a large cohort of patients undergoing liver resection for colorectal liver metastases (CRLM). METHODS: Between 2003 and 2013, 334 patients underwent hepatic resection for CRLM at Johns Hopkins Hospital and met the inclusion criteria. Clinicopathologic characteristics, perioperative details, and outcomes were stratified by KRAS status-mutant KRAS (mtKRAS) versus wild-type KRAS (wtKRAS)-and analyzed. RESULTS: mtKRAS was identified in 115 (34.4 %) patients. At a median follow-up of 28.2 months, recurrence was observed in 59 (51.3 %) patients with mtKRAS and 117 (53.4 %) patients with wtKRAS (P = 0.79); there was no difference in the pattern of recurrence (liver: mtKRAS 39.0 % vs. wtKRAS 52.1 %; lung: mtKRAS 55.6 % vs. wtKRAS 64.3 %; both P > 0.05). Although 5-year log-rank overall survival (OS) was comparable among mtKRAS (41.6 %) vs. wtKRAS (48.5 %), on multivariable Cox survival analysis and after adjusting for known predictors of OS mtKRAS was associated with worse OS (hazard ratio 1.65; 95 % confidence interval 1.07-2.54; P = 0.02). Among patients who experienced a recurrence, 5-year OS was worse among those patients who had mtKRAS (mtKRAS 28.1 % vs. wtKRAS 44.5 %; P = 0.004). After controlling for tumor factors and receipt of chemotherapy, mtKRAS status remained independently associated with a worse outcome among patients who experienced recurrence (hazard ratio 2.07; 95 % confidence interval 1.31-3.27; P = 0.002). CONCLUSIONS: mtKRAS was noted in one-third of patients with CRLM. Although KRAS status did not affect the pattern of recurrence and recurrence-free survival, mtKRAS was an independent predictor of worse OS. The effect was more pronounced among patients who experienced a recurrence after resection of CRLM.

The Role of Neoadjuvant Therapy in Characterizing Indeterminate Lung Lesions in Patients with Resectable Colorectal Liver Metastases.

BACKGROUND: Incidental pulmonary lesions are frequently found during the preoperative evaluation of patients considered for resection of colorectal liver metastases (CRLM), and their presence can confound management decisions. This study investigates the role of clinical and radiologic factors, including response to preoperative systemic chemotherapy, in determining the malignant probability of these lesions. METHODS: Computed tomography (CT) scans of 33 patients with small (≤1 cm) lung lesions undergoing resection for CRLM after preoperative chemotherapy were reviewed. Radiological features were recorded from three sequential CT scans (baseline, postchemotherapy, and follow-up). Malignancy was diagnosed either by resection or serial imaging. Chemotherapy response comparing lung lesions and CRLM was categorized as: (1) concordant or (2) discordant. Chemotherapy response, imaging features, and other clinical factors were evaluated in multivariate analyses as predictors of malignancy. RESULTS: Among the 86 indeterminate lung lesions identified, 23 % (20/86) were found to be metastases on follow-up. Lesions 6-10 mm were more likely to be metastases (odds ratio [OR] = 3.14, p = 0.045), as were lesions located in the lower lobes (OR = 4.50, p = 0.018). Concordant chemotherapy response was found in 13 of 86 (15 %) and was independently associated with metastatic disease (OR = 19.87, p < 0.001), with 11 of 13 (85 %) lesions determined to be metastases. In contrast, only 9 of 73 lesions (12 %) with discordant response were found to be metastases. CONCLUSIONS: Lesion size, location, and chemotherapy response pattern were independent predictors of malignancy for patients with resectable CRLM and small indeterminate lung lesions. Utilization of preoperative chemotherapy can be a useful method of ruling out pulmonary metastases in these patients.