Impact of conversion surgery after chemotherapy in patients with initially unresectable and recurrent biliary tract cancer

Purpose: Gemcitabine, cisplatin, and S-1 chemotherapy was superior to gemcitabine and cisplatin chemotherapy for progression-free survival and overall survival for unresectable and recurrent biliary tract cancer in a randomized phase III trial (KHBO1401). This study aimed to evaluate the outcome of conversion surgery after chemotherapy in biliary tract cancer patients (ancillary study, KHBO1401-3C).Methods: A total of 246 patients were enrolled in KHBO1401. We compared progression-free and overall survivals between the conversion surgery and non-conversion surgery groups.Results: Eight patients (3.3%) underwent conversion surgery with chemotherapy, seven of whom were diagnosed with unresectable disease and one with recurrence. Six and two patients received gemcitabine, cisplatin, and S-1 chemotherapy as well as gemcitabine and cisplatin chemotherapy, respectively. Three patients in the conversion surgery group who received gemcitabine, cisplatin, and S-1 chemotherapy showed no disease progression and survived without postoperative chemotherapy. Preoperative carbohydrate antigen 19-9 (CA19-9) level was a prognostic factor for conversion surgery. After correcting for immortal time bias, 1-year progression-free survival rates in the conversion surgery and non-conversion surgery groups were 50.0% and 19.0%, respectively (hazard ratio 0.343, 95% confidence interval 0.286-0.843, p = 0.0092). One-year overall survival rates in the conversion surgery and non-conversion surgery groups were 87.5% and 56.0%, respectively (hazard ratio 0.222, 95% confidence interval 0.226-0.877, p = 0.0197).Conclusions: Conversion surgery might be an option for the treatment of unresectable and recurrent biliary tract cancer in patients with normal preoperative CA19-9 level.