While caffeine consumption has not been linked to an overall increase in breast cancer in the general population, a high intake of caffeine may increase the risk of breast cancer in women who have a history of benign, or non-cancerous, breast disease, according to a study published in the Archives of Internal Medicine .

Researchers from Brigham and Women's Hospital and Harvard Medical School and their colleagues studied detailed dietary information from 38,432 women aged 45 and older who were free of cancer and followed these women for 10 years. They found that, in general, consumption of caffeinated foods and beverages was not associated with an overall risk of breast cancer. However, in women with benign breast disease, there was a borderline significant positive association between breast cancer risk and the highest intake of caffeine.

The researchers also found a link between high caffeine consumption and the risk of developing breast tumors that were either hormone-receptor negative or larger than 2 centimeters. They conclude that their findings indicate that caffeine consumption may affect breast cancer progression, but state that these findings still warrant further study.

Source

Arch Intern Med. 2008:168:2022-2031.