PROSPECT Eligibility and Clinical Outcomes: Results From the Pan-Canadian Rectal Cancer Consortium.

BACKGROUND: The PROSPECT trial (N1048) is evaluating the selective use of chemoradiation in patients with cT2N1 and cT3N0-1 rectal cancer undergoing sphincter-sparing low anterior resection. We evaluated outcomes of PROSPECT-eligible and -ineligible patients from a multi-institutional database. PATIENTS AND METHODS: Data from patients with locally advanced rectal cancer who received chemoradiation and low anterior resection from 2005 to 2014 were retrospectively collected from 5 Canadian centers. Overall survival, disease-free survival (DFS), recurrence-free survival (RFS), and time to local recurrence (LR) were estimated using the Kaplan-Meier method, and a multivariate analysis was performed adjusting for prognostic factors. RESULTS: A total of 566 (37%) of 1531 patients met the PROSPECT eligibility criteria. Eligible patients were more likely to have better PS (P = .0003) and negative circumferential resection margin (P < .0001). PROSPECT eligibility was associated with improved DFS (hazard ratio [HR], 0.75; 95% confidence interval [CI], 0.61-0.91), overall survival (HR, 0.73; 95% CI, 0.57-0.95), and RFS (HR, 0.68; 95% CI, 0.54-0.86) in univariate analyses. In multivariate analysis, only RFS remained significantly improved for PROSPECT-eligible patients (HR, 0.75; 95% CI, 0.57-1.00, P = .0499). The 3-year DFS and freedom from LR for PROSPECT-eligible patients were 79.1% and 97.4%, respectively, compared to 71.1% and 96.8% for PROSPECT-ineligible patients. CONCLUSION: Real-world data corroborate the eligibility criteria used in the PROSPECT study; the criteria identify a subgroup of patients in whom risk of recurrence is lower and in whom selective use of chemoradiation should be actively examined.

Predictors of Pathologic Complete Response After Neoadjuvant Treatment for Rectal Cancer: A Multicenter Study.

BACKGROUND: Pathologic complete response (pCR) to neoadjuvant chemoradiation (CRT) for rectal cancer is associated with better long-term outcomes, and is used as an early indicator of response to novel agents. To assess the rate and predictors of pCR, we performed a retrospective multicenter study involving 5 Canadian cancer centers. PATIENTS AND METHODS: Cancer registries identified consecutive patients with locally advanced rectal adenocarcinoma from the Tom Baker Cancer Centre, Cross Cancer Institute, British Columbia Cancer Agency, Ottawa Hospital Cancer Centre, and the Dr H. Bliss Murphy Cancer Centre who received fluoropyrimidine-based CRT and had curative intent surgery from 2005 to 2012. Patient, tumor, and therapy characteristics were correlated with response. RESULTS: Of the 891 patients included, 885 patients had pCR data available. Of the included patients, 161 (18.2%) had a pCR to CRT, and 724 (81.8%) did not. Patients with a pCR had a lower pretreatment carcinoembryonic antigen (CEA) level, and higher hemoglobin level in univariate analysis. In multivariable analysis, statin use at baseline (odds ratio [OR], 1.7; 95% confidence interval [CI], 1.02-2.92; P = .04), lower pretreatment CEA level (OR, 1.03; 95% CI, 1.01-1.06; P = .03), and distance closer to anal verge (OR, 1.07; 95% CI, 1.01-1.15; P = .04) were significant predictors of pCR. The 3-year disease-free survival was 86% in those with a pCR versus 62.5% in those without a pCR (P < .0001) and pCR was associated with improved overall survival (hazard ratio, 0.29; 95% CI, 0.17-0.51; P < .0001). CONCLUSION: Lower pretreatment CEA level, proximity to anal verge, and statin use are predictors of pCR in our large retrospective cohort. Clinical trials to investigate statins combined with neoadjuvant CRT might be warranted.