Advantage of adjuvant radiation therapy in octogenarians undergoing surgical resection of rectal cancer.

Abstract

650 Background: Radiation in patients with rectal cancer is an important adjuvant therapy. It can be given either pre-operative or post-operative phase or both. However the optimum timing of the radiation in terms of pre-operative or post-op phase remains a question of debate in octogenarian patients as there is lack of enough evidence. Methods: In this study we aim to find the optimum time of radiation therapy in octogenarians with rectal cancer undergoing surgical resection. Octogenarians with rectal cancer were selected from surveillance, Epidemiology and End Results (SEER) database collected between 1998 and 2009. The data set contained 4,026 patients with rectal cancer who underwent surgical resection and radiation therapy. They were divided into 3 groups. 1,586 (39%) patients had radiation before the surgery. 66 (2%) patients had radiation before and after the surgery, also called the combination group. 2,347(59%) patients had radiation after the surgery. Taking in the consideration of unequal sample sizes, Tukey-Kramer multiple comparison tests was used to compare the mean survival of the patients in each group. Results: The mean survival in pre-operative radiation group was 37.7 months, in combination group was 48.41 months and post-operative radiation group was 44.3 months. There was no statistically significant difference in survival time between the combination group and the radiation after surgery group (p-value=0.64). There was marginal statistical significance in survival time between the combination group and the before surgery group (p-value=.05). There was a statistically significant difference in survival time between the radiation after surgery group and the radiation before surgery group (p-value<0.0001). Conclusions: Octogenarian patients with rectal cancer undergoing adjuvant radiation therapy, with or without neoadjuvant radiation, have greater survival than compared to neoadjuvant only radiation. There appears to be survival advantage of postoperative radiation therapy in octogenarian patients with rectal cancer.