Research progress on the correlation between vitamin D and colorectal cancer: opportunities and challenges

Colorectal cancer (CRC) ranks as the third most common cancer worldwide and is the second leading cause of cancer-related fatalities. The treatment and prognosis of CRC have drawn increasing attention. Currently, the main treatment modality is comprehensive therapy, with surgical treatment as the primary approach supplemented by radiotherapy and chemotherapy. However, for patients with metastatic and advanced CRC, how to improve their prognosis and quality of life remains a challenging research topic. Vitamin D, an essential fat-soluble vitamin in the human body, possesses functions that go beyond simply regulating calcium and phosphorus metabolism. A growing body of evidence has validated a significant correlation between CRC and vitamin D. This article systematically elaborates on the physiological functions, sources, metabolic pathways of vitamin D, the influencing factors of its content in the body, and comprehensively reviews the relationship between vitamin D and CRC as well as their clinical research applications from aspects including the cancer-inhibiting mechanism of vitamin D, the reactivity of CRC patients with different genotypes to vitamin D, the differences in vitamin D content in patients with tumors at different anatomical sites, and the regulation of intestinal flora balance mediated by vitamin D. The aim is to provide references for the prevention and treatment of colorectal cancer in the future.