Impacts of postoperative radiotherapy on long-term survival of patients with locally advanced biliary tract cancers——a propensity score-matched analysis based on the SEER database / 中华放射医学与防护杂志

ABSTRACT

Objective:To explore the impacts of postoperative radiotherapy on long-term survival of the patients with resectable locally advanced (T 3-4and/or N +) biliary tract cancers (BTCs) and to analyze the prognostic factors. Methods:The patients with locally advanced gallbladder cancer ( n=1 922) and the patients with extrahepatic biliary duct cancer ( n=3 408) who received surgical resection during 2006-2016 were selected from the Surveillance, Epidemiology, and End Result (SEER) database. They were grouped according to different treatment schemes (only surgery and surgery + radiation). The propensity score matching (PSM) method was employed to adjust the differences in baseline prognostic characteristics between patients who received only surgery and those treated with surgery+ radiation. The role of the two treatment schemes on the survival of the patients was analyzed using the Kaplan-Meier method and the prognosis factors were assessed using the Cox regression. Results:The 1 174 patients with gallbladder cancers and the 2 144 patients with extrahepatic biliary duct cancer were respectively matched according to propensity scores. The postoperative radiotherapy showed a significant advantage in 5-year cancer-specific survival (CSS) compared to only surgery for both the patients with gallbladder cancer ( χ2=35.73, P< 0.001) and those with extrahepatic biliary duct cancer ( χ2=9.878, P=0.002). After adjusting related covariates, independent prognostic factors for all the patients included pathological grading, T status, N status, treatment pattern, and age. For the patients with extrahepatic biliary duct cancer, independent prognostic factors also included race and year of diagnosis. The benefits of postoperative radiotherapy were observed in various clinicopathologic characteristics except for the patients with T 1-2 gallbladder cancer and the extrahepatic biliary duct cancer patients with a pathological grade of Ⅰ-Ⅱ and N 0 status or with age ≥ 70. Conclusions:Long-term survival benefits can be gained through postoperative radiotherapy for the patients with resectable locally advanced (T 3-4 and/or N+ ) BTCs. However, adjuvant radiation should be cautiously adopted for the patients with T 1-2 gallbladder cancer and the extrahepatic biliary duct cancer patients with a pathological grade of I-Ⅱ and N 0 status or with age ≥70.