Women who suffer from Depression are at increased risk of developing Colorectal cancer, according to a new analysis of data from the Nurses’ Health Study, an ongoing study of some 127,000 female nurses.

However, the researchers found no link between depressive symptoms and the risk of colorectal adenomas - growths or polyps that can become cancerous.

While Depression has long been thought to play a role in the development of cancer, the data are inconclusive, 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.

Depression has been tied to certain risk factors for Colorectal cancer, they add, including diabetes, low estrogen levels, and behavioral risk factors such as smoking.

The researchers hypothesized that Depression would increase the risk of both Colorectal cancer and colorectal adenomas. Their study is the first to look specifically at Depression and Colorectal cancer.

They analyzed data from 81,612 women, all of whom were free of cancer at the study’s outset. Four hundred cases of Colorectal cancer and 680 colorectal adenomas were diagnosed in the study population during the 8-year follow-up period.

Women found to have the highest levels of depressive symptoms on a Mental Health Index had a 43 percent increased risk of Colorectal cancer compared with the women with the lowest levels, the researchers found. The association was stronger among overweight women.

This suggests, the researchers note, that Depression may worsen obesity’s adverse effects on cancer development. Further research will be needed, they conclude, to identify potential biological factors through which depressive symptoms may promote Colorectal cancer development.

SOURCE: American Journal of Epidemiology, November 1, 2005.