Proposed Definition for Oligometastatic Recurrence in Biliary Tract Cancer Based on Results of Locoregional Treatment: A Propensity-Score-Stratified Analysis

Background Oligometastatic recurrence involves relapsed tumors for which locoregional treatment (LT) may yield a survival benefit. However, there are no clear criteria for selecting patients for LT or determining the effects of LT in recurrent biliary tract cancer (BTC). The aim of this retrospective study is to assess the effects of LT on survival outcomes and to identify potential criteria for selecting LT in recurrent BTC. Patients and Methods In the present work, 232 consecutive patients with recurrent BTC who initially underwent curative surgery between 1996 and 2015 were evaluated. The primary outcome was length of survival after recurrence (SAR). Propensity score stratification with various tumor-related factors was used to identify patients who would likely benefit from LT. Results Among the cohort, 60 (25.9%) patients underwent LT, whereas 172 (74.1%) patients did not. The multivariate Cox model identified carbohydrate antigen 19-9 levels of > 50 U/mL, multiorgan recurrence, tumor number > 3, tumor size > 30 mm, and early recurrence (≤ 1 year) as independent predictors of poor SAR ( P 1 year) (median SAR: 48.6 vs. 14.2 months, n = 33 vs. n = 34, hazard ratio: 0.10, 95% confidence interval: 0.04–0.20, P