Background: Neoadjuvant therapy, followed by surgery, reduces the risk of local relapse in rectal cancer, but approximately 30% will relapse with distant metastases, highlighting the importance of adjuvant chemotherapy (aCT). Objective: The objective of the study was to study two regimens of adjuvant treatment in patients with locally advanced rectal cancer and analyze their efficacy and toxicity. Methods: Between January 2009 and December 2016, 193 patients with Stage II-III rectal cancer who had received neoadjuvant therapy were included by consecutive non-probability sampling. The decision to administer aCT, as well as the specific regimen, was at the discretion of the medical oncologist. Disease-free survival (DFS) and overall survival (OS) were calculated. Results: The mean DFS was 84.85 (95% confidence interval [CI]: 79-90) months in 164 patients receiving aCT, compared to 57.71 (95% CI: 40-74) months in 29 who did not receive aCT (p < 0.001). Then, mean OS was 92.7 (95% CI: 88-97) months and 66.18 (95% CI 51-81) months, respectively (p < 0.001). DFS was 83.6 (95% CI: 76-91) months in 74 patients receiving adjuvant 5-fluorouracil (5-FU), and 82.9 (95% CI: 75-90) months in 90 receiving 5-FU plus oxaliplatin (p = 0.49). OS was 87 (95% CI: 80-94) versus 93.65 (95% CI: 88-99) months, respectively (p = 0.76). The multivariate analysis identified aCT hazard ratio (HR) 0.30 (95% CI: 0.1-0.46), perineural invasion HR 3.36 (95% CI: 1.7-6.5), and pathological complete response HR 0.10 (95% CI: 0.01-0.75) as independent markers of DFS. Conclusions: In our study, aCT was associated with longer DFS and OS. 5-FU plus oxaliplatin showed greater toxicity with no added benefit in DFS or OS.

To study the effect of the pathologic complete response (pCR) on the survival of patients treated with surgery and neoadjuvant chemo-radiotherapy in locally advanced non-metastatic rectal carcinoma (LARC). Materials and methodology We underwent an observational retrospective analysis of cohorts. The recruitment was carried out by means of non-probabilistic consecutive inclusion of patients with rectal cancer treated between January 2009 and December 2016 with surgery and neoadjuvant chemo-radiotherapy. The patients recruited had been diagnosed with locally advanced non-metastatic rectal cancer. cT3-4 o N+. based on the American Joint Committee on Cancer (AJCC) 2010. with histological confirmation of adenocarcinoma and no treatment with induction chemotherapy. The pathologic response was calibrated in accordance with the Ryan system. Survival was calculated with multivariate Cox regression analysis Results Pathologic complete response was reached by 19.2% Patients. The disease free survival was significantly lower in the no pathologic complete response (HR 0.099. p value 0.025). The progression in the group of patients with pathological complete response occurred in only one patient and have local and distal component compared to 39 patients in no pCR 21.2% distant metastases and 3.8% locally relapse. Perineural invasion and adjuvant chemotherapy were also significatly associated with disease free survival Conclusions The pathological complete response is a good prognosis factor in patients treated with surgery and nCRT in LARC with distal and local relapse. Perineural invasion and adjuvant chemotherapy were also good prognostic factors.

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