Clinical Efficacy of Hypofractionated Proton Beam Therapy for Intrahepatic Cholangiocarcinoma

SIMPLE SUMMARY: Proton beam therapy (PBT) has the potential to improve local tumor control and subsequently improve survival of patients with inoperable or recurrent intrahepatic cholangiocarcinoma (IHCC); however, studies on PBT in patients with IHCC are still limited. This study evaluated the efficacy and safety of hypofractionated PBT in IHCC patients with inoperable or recurrent disease. Our findings demonstrated that hypofractionated PBT was considered tolerable and safe and offers a high rate of local tumor control and promising survival in patients with IHCC. In addition, the survival outcomes in selected patients with localized disease treated with hypofractionated PBT were comparable to those of surgical resection. Further large-scale studies are warranted to confirm these findings. ABSTRACT: Forty-seven patients with intrahepatic cholangiocarcinoma (IHCC) who received proton beam therapy (PBT) were analyzed to evaluate the clinical efficacy and safety of hypofractionated PBT in patients with inoperable or recurrent IHCC. The median prescribed dose of PBT was 63.3 GyE (range: 45–80 GyE) in 10 fractions, and the median duration of follow-up in all the patients was 18.3 months (range: 2.4–89.9 months). Disease progression occurred in 35 of the 47 (74.5%) patients; local, intrahepatic, and extrahepatic progression occurred in 5 (10.6%), 20 (42.6%), and 29 (61.7%) patients, respectively. The 2-year freedom from local progression (FFLP), progression-free survival (PFS), overall survival (OS) rates, and median time of OS were 86.9% (95% confidence interval [CI], 74.4–99.4%), 16.8% (95% CI, 4.3–29.3%), 42.7% (95% CI, 28.0–57.4%), and 21.9 months (95% CI, 16.2–28.3 months), respectively; grade ≥ 3 adverse events were observed in four (8.5%) patients. In selected patients with localized disease (no viable tumors outside of the PBT sites), the median time of OS was 33.8 months (95% CI, 5.4–62.3). These findings suggest that hypofractionated PBT is safe and could offer a high rate of FFLP and promising OS in patients with inoperable or recurrent IHCC.