Impact of postoperative irradiation after non-curative resection of hilar biliary cancer

Background: The aim of this retrospective study was to determine the effect of surgical margin on the outcome of postoperative radiotherapy (RT) in patients with resected hilar biliary cancer. Methods: The study subjects were 87 patients with hilar biliary cancer resected surgically before 2008. Based on the Japanese Society of Biliary Surgery (JSBS) criteria for diagnosis of biliary cancer, the surgical margin status was categorized as margin 1 (histopathologically margin negative, but cancer cells identified within 5mm from the margin), margin 2 (histopathologically margin positive), and margin 0 (other margin status). Results: The surgical margin was 1 or 2 in 44 patients and 21 of these patients underwent RT. The 3-year overall survival and progression-free survival rates of the RT and non-RT groups were 47% and 23% (P=0.0392), and 49% and 19% (P=0.0197), respectively. Univariate and multivariate analyses identified RT as the only factor that influenced survival. Subgroup analysis showed that the effect of RT was dependent on pathologically negative lymph node metastasis and positive margin (margin 2). Conclusion: Postoperative RT is beneficial for patients with margins 1 and 2, especially those who are lymph node metastasis negative and have histopathologically positive margin.