Insurance Co-Payment Status and Advanced-Stage Presentation of Colorectal Cancer in a Universal Healthcare System: A Surgical Cohort Study From Japan.

Colorectal cancer (CRC) is one of the most common malignancies worldwide and remains a leading cause of cancer-related mortality, particularly in aging societies such as Japan. The stage at diagnosis is a major determinant of prognosis, with stage IV disease associated with poor outcomes despite advances in systemic therapy.