Impact of Adjuvant Radiation Therapy for Microscopic Residual Tumor After Resection of Extrahepatic Bile Duct Cancer

The effect of adjuvant radiation therapy (RT) in extrahepatic bile duct (EHBD) cancer patients with microscopic-positive resection margins (R1 resection) is still controversial.Between January 2000 and March 2010, 52 patients with EHBD cancer underwent surgery at our institution, of whom 36 were subjected to a retrospective analysis. Eleven patients received adjuvant RT after resection [surgery (S)+RT group], which included 9 patients with R1 resection and 2 with para-aortic lymph node metastasis. Their oncological outcomes were analyzed and compared with those of the 25 patients with R0 resection who did not receive adjuvant RT (S group).Patients in the S+RT group had significantly more advanced disease than those in the S group. However, there was no significant difference in disease-free survival or overall survival between the 2 groups. Median survival times for the S+RT and the S groups were 44 and 47 months, respectively, whereas the 5-year survival rates were 38.9% and 46%, respectively (P=0.707). Locoregional recurrence was less frequent in the S+RT group as compared with the S group, but the incidence of distant metastasis was unaffected by the adjuvant RT.Our results support the beneficial effect of adjuvant RT in EHBD cancer patients with R1 resection. This effect seems to result from an improved control of the locoregional tumor by adjuvant RT.