Impact on overall survival and disease-free survival of adjuvant chemotherapy after neoadjuvant chemoradiotherapy for rectal cancer.

Abstract

e14173 Background: Colorectal cancer is the second most common cancer with 2,4 million people diagnosed. The rectal cancer (RC) is 27% of these cases. Neoadjuvant chemoradiotherapy (NCRT) has become standard but brought controversy in the adjuvant treatment. The objective was to assess the impact of adjuvant chemotherapy after NCRT. Methods: Between mar/96 and Oct/2010, 84 patients received NCRT, and 58 patients underwent resection of the rectum. The NCRT consisted of 5-FU 350mg/m2, D1-D5 (50% of cases) or 5-FU 425mg/m2, D1-D3 (43%) with LV 20mg/m2 bolus in the 1st and 5th week of the 25 sessions of radiotherapy in linear accelerator (total 45 - 50 Gy). When performed, Adjuvant chemotherapy (ADJC) consisted of 5-FU 425mg/m2, LV 20mg/m2, both on D1-D5 for 4 cycles. Evaluation of Overall Survival (O.S) and Disease-Free Survival (DFS) performed using Kaplan-Meier curve in SPSS version 13.0 Results: Of the 58 patients who underwent surgery, 90% were stage II, 51% occurred in the lower rectum and 66% were ECOG 1. Pathologic Complete Response (PCR) was obtained in 25.8% (15) of patients (group 1). Of these, 20% (3) received ADJC. Patients without PCR (group 2) received ADJC in 51% of the cases (22). The mean follow-up was 41 months. Both the DFS (HR: 2.594, 95% CI: 1134-5938, p = 0.024) and OS (HR: 2.615, 95% CI: 1005-6807, p = 0.0488) were higher in patients with PCR independent of the use of ADJC. On the other hand, patient treated with ADJC vs without ADJC, independent of presence of PCR, did not alter DFS (p = 0.74) or OS (p = 0.32). In PCR patients, ADJC do not interfere in the outcome (DFS, p = 0.76; SG, p = 0.73). In group 2 (patients without PCR), the subgroup with ADJC, there was a trend towards better SLD (p = 0.06) and OS (p = 0.06). Those who did not receive ADJC in group 2 had worse SLD (p = 0.011) and OS (p = 0.028) compared with group-1. Conclusions: Adjuvant treatment after NCRT did not increase OS or DFS. Patients without PRC had worse results without ADJC, compared to those with PCR. The first, probably, the subgroup of patients who benefited most from the use of ADJC. PCR improves OS and DFS regardless of ADJC, being perhaps the group that does not deserve ADJC.