Tumor-related local complications as a major contributor to mortality after definitive radiotherapy for unresectable extrahepatic bile duct cancer.

PURPOSE: This study investigated oncologic outcomes and causes of death after radiotherapy in patients with unresectable extrahepatic bile duct cancer.

METHODS

We retrospectively analyzed 74 patients with localized unresectable or inoperable extrahepatic bile duct cancer treated with conventionally fractionated radiotherapy between September 2005 and February 2019. Fifty-five patients (74.3%) underwent three-dimensional conformal radiotherapy, and 19 patients (25.7%) received intensity-modulated radiotherapy. Induction chemotherapy was administered in 18 patients and 57 patients received concurrent chemotherapy.

RESULTS

Among all patients, 90.5% (67/74) had perihilar bile duct cancer, and the median radiotherapy dose was 54.0 Gy. With a median follow-up of 16.2 months, the median progression-free survival and overall survival were 11.5 and 18.3 months, respectively. Distant metastasis was the predominant first failure pattern (52.7%), followed by locoregional progression (20.3%). The 1- and 2-year freedom from local progression rates were 86.3% and 36.2%, respectively. Cholangitis, liver failure, and tumor bleeding accounted for 26 of 65 deaths, corresponding to at least 40.0% of all deaths. Radiotherapy dose above 54 Gy was not significantly associated with freedom from local progression, progression-free survival, or overall survival. No patients experienced grade ≥ 3 acute gastrointestinal toxicity, whereas grade ≥ 3 late toxicities occurred in 8.1%.

CONCLUSION

Definitive radiotherapy provided favorable local control with acceptable toxicity in unresectable extrahepatic bile duct cancer. Although distant metastasis was the predominant failure pattern, local complications accounted for at least 40% of deaths, supporting continued efforts to optimize local treatment alongside emerging systemic therapies.