e15609 Background: Locally advanced unresectable intrahepatic cholangiocarcinoma (IHCC) remains incurable. Prior data has shown the effectiveness of hypofractionated radiation therapy (HRT) with biological equivalent doses (BED) greater than 80.5 Gy in improving local control and survival for this patient population. This is an updated report of our IHCC experience with HRT in 15 or 25 fractions using a simultaneous integrated boost technique. Methods: A retrospective analysis of 63 patients (median age 64, range 29-87) diagnosed between 2007-2016 who received HRT was performed. RT dose ranged from 58-90 Gy in 15 fractions and 62.5-100 Gy in 25 fractions, translating to a median BED of 97.5 (range 78.1-144 Gy). Median primary tumor size at diagnosis was 7.8 cm (2.4-17cm). Forty-eight (76%) patients received gemcitabine-based therapy prior to HRT. Results: Median follow up was 31 months (4-110). The 2 year overall-survival (OS), local-progression-free-survival (LPFS), intrahepatic-distant-metastasis-free-survival (IH-DMFS) and extraheptic-distant-metastasis-free-survival (EH-DMFS) were 71% (95% CI 58-82), 67% (95% CI 50-80), 40% (95% CI 28-54) and 40% (95% CI 27-54) respectively. Pattern of failure analysis revealed 16 patients with local failure after HRT, of which only 5 (8% of total) progressed within the high iso-dose field line (BED > 80.5). After HRT, 41 (65%) patients had intrahepatic metastasis that occurred outside the radiation field, and 34 (54%) patients developed extrahepatic metastasis. On multi-variate analysis, T-stage was an independent predictor of OS, LPFS, IH-DMFS, and EH-DMFS. Larger normal liver volume and 15 fraction treatments were independently associated with better LPFS and IH-MFS respectively. There were no significant HRT-related toxicities. Conclusions: HRT demonstrates safety and efficacy for durable local control and prolonged overall survival in patients with unresectable IHCC. Dominant modes of failure are outside the HRT field. Improvements in systemic therapies could further improve outcomes for this patient population.
Hypofractionated Radiation Therapy for Unresectable/Locally Recurrent Intrahepatic Cholangiocarcinoma
