Log odds of metastatic lymph nodes is crucial for improving outcomes in patients undergoing surgery for perihilar cholangiocarcinoma.

• Patients with log odds of metastatic lymph nodes ≥ -2.0 saw a survival advantage from adjuvant chemotherapy (31.3 months vs 20.1 months).
• Those with log odds < -2.0 showed no survival benefit (69.2 months vs 51.0 months).

Utilizing log odds of metastatic lymph nodes can better guide decisions on adjuvant treatment, helping select patients who will benefit most.