Impact of intraluminal brachytherapy on survival outcome for radiation therapy for unresectable biliary tract cancer: a propensity-score matched-pair analysis.

Purpose: To determine whether adding intraluminal brachytherapy (ILBT) to definitive radiation therapy (RT) for unresectable biliary tract cancer has a positive impact on survival outcome.

Methods And Materials: The original cohort comprised 209 patients, including 153 who underwent external beam RT (EBRT) alone and 56 who received both ILBT and EBRT. By matching propensity scores, 56 pairs (112 patients) consisting of 1 patient with and 1 patient without ILBT were selected. They were well balanced in terms of sex, age, performance status, clinical stage, jaundice, and addition of chemotherapy. The impact of ILBT on overall survival (OS), disease-specific survival (DSS), and local control (LC) was investigated.

Results: The 2-year OS rates were 31% for the ILBT+ group and 40% for theILBT- group (P=.862). The 2-year DSS rates were 42% for the ILBT+ group and 41% for the ILBT- group (P=.288). The 2-year LC rates were 65% for the ILBT+ group and 35% for the ILBT- group (P=.094). Three of the 4 sensitivity analyses showed a significantly better LC for the ILBT+ group (P=.010, .025, .049), and another showed a marginally better LC (P=.068), and none of the sensitivity analyses showed any statistically significant differences in OS or DSS.

Conclusions: In the treatment for unresectable biliary tract cancer, the addition of ILBT to RT has no impact on OS or DSS but is associated with better LC. Therefore, the role of ILBT should be addressed by other measures than survival benefit, for example, by less toxicity, prolonged biliary tract patency decreasing the need for further palliative interventions, or patient quality of life.