Link Between Depression and Colorectal Cancer

According to a new analysis of data from the Nurses' Health Study, an ongoing study of some 127,000 female nurses, women who suffer from depression are at an increased risk of developing colorectal cancer.
Researchers however have found no link between depressive symptoms and the risk of colorectal adenomas, which are growths or polyps that can become cancerous. Dr. Candyce H. Kroenke of Brigham and Women's Hospital and Harvard Medical School in Boston, and colleagues explain in the American Journal of Epidemiology that while depression has long been thought to play a role in the development of cancer, the data are inconclusive. But they add that depression has been tied to certain risk factors for colorectal cancer, including diabetes, low estrogen levels, and behavioral risk factors such as smoking.
Researchers hypothesized that depression would increase the risk of both colorectal cancer and colorectal adenomas. They are the first to look specifically at depression and colorectal cancer. Data analyzed from 81,612 women, all free from cancer at the study's onset, showed 400 cases of colorectal cancer and 680 colorectal adenomas were diagnosed during the 8 year follow up period. Women with the highest levels of depressive symptoms on the Mental Health Index had a 43 percent increased risk of colorectal cancer compared to women with lower levels. The association was stronger among overweight women. These findings suggest that depression may worsen obesity's adverse effects on cancer development. They concluded that further research will be needed to identify potential biological factors through which depressive symptoms may promote colorectal cancer development.