Proton beam therapy for unresectable intrahepatic cholangiocarcinoma

Background and Aim Treatment for unresectable intrahepatic cholangiocarcinoma (ICC) has not been established. The aim of the study was to evaluate the outcome of proton beam therapy (PBT) for patients with unresectable ICC. Methods Up to 2010, 20 patients (11 males, 9 females, median age 63 years old) with unresectable ICC (two, seven, seven, and four in stages II, IIIA, IIIC, and IV, respectively) were treated with PBT. The largest dimensions of the tumors ranged from 15 to 140 mm (median: 50 mm). The intrahepatic region and lymph nodes received median total proton doses of 72.6 GyE in 22 fractions and 56.1 GyE in 17 fractions, respectively. Four patients received concurrent chemotherapy (tegafur, gimeracil, and oteracil; TS‐1) during PBT. Twelve patients were treated curatively, and eight were treated palliatively because tumors were present outside the irradiation field. Results In the curative group, nine tumors within the irradiated field were controlled in follow‐up of 8.6–62.6 months (median: 20.8 months). Median survival rates in the curative and palliative groups were 27.5 and 9.6 months, respectively, and overall 1‐ and 3‐year survival rates were 82% and 38%, and 50% and 0%, respectively. Eight patients survived for > 2 years, and there was no distant metastasis in five of these patients after 2 years. No severe side‐effects occurred. Conclusions The results suggest that long‐term survival can be achieved using PBT for patients with unresectable ICC without distant metastasis. Further studies are required to determine the optimal treatment schedule and best combination of PBT and chemotherapy.