Liver Oligometastasis in Biliary Tract Cancer and Impact on Survival Outcomes

Outcomes of unresectable biliary tract cancer (BTC) with varying extents of liver involvement remain unclear. We evaluated characteristics and outcomes of BTC patients with liver metastases who underwent chemotherapy. We retrospectively reviewed consecutive BTC patients with synchronous or metachronous intrahepatic metastases who started first-line chemotherapy at our institution between January 2016 and December 2021. Ninety-six patients were included, of which 57 only had liver metastases and 39 had multiorgan involvement. The liver only group had longer median overall survival (OS) (11.8 vs. 7.4 months, P = 0.006) and median progression-free survival (PFS) (4.1 vs. 2.7 months, P = 0.035) than the multiorgan group. Patients with oligometastases (defined as no more than three liver metastases) achieved longer OS than those with polymetastases (four or more liver metastases) in the entire cohort. Within the liver only group, there were no significant differences in OS or PFS between the oligometastasis and polymetastasis groups. Patients who underwent subsequent surgery had significantly longer median OS than those who did not (44.4 vs. 7.7 months, P < 0.001). Age ≥ 75 years, liver-only metastasis, modified Glasgow prognostic score ≥ 1 carcinoembryonic antigen ≥ 5 μg/L, and subsequent surgery were independent predictors of OS. Liver oligometastasis was only a significant predictor of longer OS in univariate Cox analysis. Outcomes in BTC patients with metastases limited to the liver, particularly those with oligometastasis, were more favorable than those with multiorgan metastases. Selected cases, generally with liver oligometastases, may achieve prolonged OS through subsequent surgery.