Advanced Biliary Tract Cancer: Exploration of Third-Line and Other Therapeutic Areas After Failure of Chemotherapy Alone.

Biliary tract cancer (BTC) is a highly aggressive malignancy with an extremely poor prognosis and a gradually increasing incidence, warranting increased clinical attention. The majority of BTC patients are diagnosed at an unresectable stage, making systemic therapy-including first-line and subsequent treatments-critical for outcomes. However, due to disparities in medical resources and limited understanding of the disease, outcomes following first- and second-line therapies remain suboptimal. In this context, third-line treatment offers a potential opportunity to further extend patient survival, although challenges such as poor treatment tolerance and significant drug-related toxicities remain. A rational integration of chemotherapy, targeted therapy, immunotherapy, and novel radiotherapy techniques may constitute a standardized third-line therapeutic strategy for BTC. This review aims to discuss potential therapeutic adaptations and options in the setting where conventional chemotherapy has failed.