Adjuvant pelvic radiotherapy in patients with stage IVA rectal adenocarcinoma.

Abstract

711 Background: For patients with stage IVA rectal cancer with liver metastases treated with curative-intent chemotherapy and surgery, the role of adjuvant pelvic radiotherapy (RT) is unclear. The purpose of this study was to evaluate the impact of pelvic RT on oncologic outcomes in this patient population. Methods: We retrospectively reviewed medical records of all patients with stage IVA rectal adenocarcinoma with liver metastases treated with curative-intent resection of the primary tumor and all liver metastases at our institution between 1991 and 2010. Patient and treatment characteristics were compared between patients who did or did not receive pelvic RT using chi-square and unpaired ttests. Survival and recurrence estimates were calculated from date of initial diagnosis using the Kaplan-Meier method. Local recurrence (LR) was defined as recurrence in the pelvis occurring at or before distant recurrence (DR). Cox regression was used to compare rates of freedom from LR (FFLR), freedom from DR (FFDR), and overall survival (OS) between patients who did or did not receive pelvic RT. Results: The analysis included 65 patients. Median patient age at diagnosis was 59 years (range, 27-87). Tumor stage was T2 (n = 4), T3 (n = 53), or T4 (n = 8). The median number of liver metastases was 2 (range, 1-14). Surgery was low anterior resection (n = 54) or abdominoperineal resection (n = 11). All patients received perioperative fluoropyrimidine based chemotherapy. Pelvic RT was administered to 35 patients (54%), either preoperatively (n = 22) or postoperatively (n = 13). Median RT dose was 50.4 Gy (range 25-58). Patient characteristics were similar for those who did or did not receive pelvic RT. Median follow-up was 3.7 years. The 3-year estimates of FFLR, FFDR and OS were 81% vs 58% (p =.056), 35% vs 29% (p =.75), and 66% vs 71% (p =.81) for RT vs no RT, respectively. Conclusions: In this analysis of patients with stage IVA rectal cancer with liver metastases undergoing curative intent therapy, pelvic RT (vs. no pelvic RT) was associated with a trend to lower rates of LR and similar rates of DR and OS.