Long-term efficacy of preoperative radiotherapy for locally advanced low rectal cancer

The purpose of this study was to assess the long-term efficacy of preoperative radiotherapy for locally advanced low rectal cancer. Between April 1990 and June 2005, all patients who underwent surgery for low rectal cancer with a pretreatment diagnosis of T3 or resectable T4 without distant metastasis were enrolled. The total dose of radiation was 45 Gy. Patients with a partial or complete response were defined as radiotherapy responders (RT-R) and the others as radiotherapy non-responders (RT-NR). Patients who did not receive radiotherapy were termed the non-radiotherapy group (NRT). The endpoint of this study was overall survival and local and/or distant metastasis. There were 24 patients in RT-R, 26 in RT-NR, and 40 in NRT. Gastrointestinal complications were commonly observed in all groups. RT-R had a significantly higher incidence of genitourinary complications. Five-year overall survival rate was 79.6% in RT-R, 58.9% in RT-NR, and 58.8% in NRT. The difference was significant in favor of RT-R over the others (P=0.015, 0.024, respectively). Five-year local recurrence-free survival rate was 100% in RT-R, 81.5% in RT-NR, and 74.9% in NRT. RT-R had significantly improved local control compared with the others (P=0.034, 0.021, respectively). Five-year distant metastasis-free survival was not statistically different among all groups. Survival benefit of preoperative radiotherapy was limited to responders. Considering the increased risk of adverse effects, identification of predictors of radiosensitivity is required in order to provide the most suitable treatment for individual patients.