Impact of Tumor Size on the Survival Benefit of Anatomic Versus Non-Anatomic Resection for Intrahepatic Cholangiocarcinoma.

Background: The role of anatomic resection (AR) versus non-anatomic resection (NAR) for intrahepatic cholangiocarcinoma (ICC) has not been thoroughly investigated. This study sought to define the impact of tumor size on the relative therapeutic benefit of AR versus NAR for ICC. Specifically, the study aimed to identify a threshold tumor size to define when AR rather than NAR may be warranted to achieve better survival outcomes for patients undergoing resection of ICC.

Methods: Patients who underwent liver resection for ICC were identified from an international multi-institutional database. A multivariable Cox model with an interaction term was used to assess the relationship between tumor size and the survival impact of AR.

Results: Among 969 patients, 506 (72.9 %) underwent AR, whereas 263 (27.1 %) had an NAR. Multivariable analysis demonstrated an interaction between tumor size and AR (hazard ratio [HR], 0.94; 95 % confidence interval [CI], 0.88-1.00; p = 0.045). A plot of the interaction demonstrated that AR was associated with improved outcomes for tumors size ≥4 cm. Among 257 (26.5 %) patients with tumors smaller than 4 cm, recurrence-free survival (RFS) did not differ between NAR and AR (3-year RFS: 65.2 % [95 % CI, 55.7-76.2] vs 58.1 % [95 % CI, 49.2-68.5]; p = 0.720). In contrast, among 712 (73.4 %) patients with tumors size ≥4 cm, AR was associated with improved RFS (3-year RFS: 34.7 % [95 % CI, 27.5-43.8] vs 44.9 % [95 % CI, 40.4-50.0]; p = 0.018).

Conclusions: Anatomic resection was associated with improved RFS for ICC patients with tumors size ≥4 cm, indicating that tumor size may be a valuable criterion to determine the extent of liver resection for resectable ICC patients.