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. OS curves of patients with and without conversion surgery.