ColorectalCancer liver metastasis detection timing—synchronous vs early or late metachronous—was not independently associated with overall survival after adjustment, supporting treatment planning guided by tumor burden and treatment feasibility.

Question Is the timing of colorectal cancer liver metastasis (CRLM) detection, defined as synchronous, early metachronous, or late metachronous, associated with overall survival?

Findings In this cohort study of 1,250 patients, synchronous CRLM initially appeared to be associated with worse survival; however, timing of detection was not an independent factor after adjusting for tumor number, size, variant status, carcinoembryonic antigen levels, and treatment strategy. The ability to undergo local treatment had the greatest association with improved survival.

Meaning These findings suggest synchronicity is not independently associated with a survival benefit and may instead be indicative of underlying tumor biology, with synchronous metastases occurring earlier in the disease course.