Pre-diagnostic 25-hydroxyvitamin D levels and subsite-specific colorectal cancer risk: A nested case-control study from the Norwegian Women and Cancer Study (NOWAC).

Colorectal cancer, the third most common cancer globally, causes over 900,000 deaths annually. Although vitamin D is observed to have potential anti-carcinogenic properties, research findings on its preventable effect against colorectal cancer remain inconclusive. Notably, different subsites within the colon and rectum may be associated with distinct risk factors.

Pre-diagnostic intake of vitamin D and incidence of colorectal cancer by anatomical subsites: the Norwegian Women and Cancer Cohort Study (NOWAC).

According to the World Cancer Research Fund International, vitamin D might decrease the risk of colorectal cancer (CRC). However, less is known about the association with cancers in different subsites of the colon and in the rectum. The aim of this study was to examine associations between pre-diagnostic intake of vitamin D and risk of CRC by anatomical subsites.