Disease Characteristics and Management of Intrabiliary Colorectal Liver Metastasis: An Updated Systematic Review

Background/Objectives: Liver metastasis develops in approximately 50% of patients with colorectal cancer. Invasion of the biliary tract from colorectal liver metastasis (CRLM) is rarely reported. Preoperative diagnosis remains elusive, prohibiting optimal surgical management. The objective of this systematic review was to summarize the clinical, radiological, pathological, and treatment characteristics of ibCRLM and describe the reported outcomes. Methods: A systematic literature search of the Medline, Embase, Web of Science, CENTRAL, and CINAHL databases was undertaken for studies reporting clinical outcomes of patients with ibCRLM, up to May 2026. An individual patient data analysis approach was utilized. Results: Thirty-eight case reports and 10 case-series, incorporating 228 patients with biliary involvement from CRLM, were identified. Mean age was 62.4 ± 10.9 years, with a male-to-female ratio of 3.2:1. The majority of metastatic lesions were metachronous in 71.1% and solitary in 59.1% of patients. Surgical treatment was implemented in 89.2% of patients. Major hepatectomy was the most common procedure, being performed in 46.2% of patients, followed by minor hepatectomy in 38.7% and pancreatoduodenectomy in 4.3%. After a median follow-up of 52.5 months (range 2-164 months), the survival rate was 60.5%. Non-survivors were found to have significantly more synchronous CRLM (50% versus 0, p = 0.008), while a single patient did not receive any curative-intent treatment and died 20 days following CRLM presentation. Conclusions: IbCRLM is a distinct clinicopathological presentation of CRLM with characteristic radiological and pathological features. The available evidence suggests that selected patients may achieve favorable long-term outcomes following complete surgical resection, although these findings should be interpreted with caution given the limitations of the available literature.