Colorectal Cancer Epidemiology in the Nurses' Health Study.

OBJECTIVES: To review the contribution of the Nurses' Health Study (NHS) to identifying risk and protective factors for colorectal adenomas and colorectal cancer (CRC).

METHODS: We performed a narrative review of the publications using the NHS between 1976 and 2016.

RESULTS: Existing epidemiological studies using the NHS have reported that red and processed meat, alcohol, smoking, and obesity were associated with an increased risk of CRC, whereas folate, calcium, vitamin D, aspirin, and physical activity were associated with decreased risk of CRC. Moreover, modifiable factors, such as physical activity, vitamin D, folate, insulin and insulin-like growth factor binding protein-1, and diet quality, were identified to be associated with survival among CRC patients. In recent years, molecular pathological epidemiological studies have been actively conducted and have shown refined results by molecular subtypes of CRC.

CONCLUSIONS: The NHS has provided new insights into colorectal adenomas, CRC etiology, and pathogenic mechanisms. With its unique strengths, the NHS should continue to contribute to the field of CRC epidemiology and play a major role in public health.