SZCZECIN, POLAND. Polish researchers report that psychological stress is a powerful risk factor for the development of breast cancer. Their study involved 257 women who had undergone breast cancer surgery during the period 1993-1998 and 565 controls who were free of breast cancer. The participants were questioned in detail about their diet, lifestyle, and reproductive history and also reported exposure to major stressful life events, stress of daily activity, and work-related stress. After adjusting for age and other known risk factors, the researchers concluded that women whose daily life was stressful, who had experienced major stressful life events (divorce, loss of spouse, etc) and suffered from depression had a 3.7 times higher risk for breast cancer than did women who did not experience such stress. Work-related stress, on its own, was associated with a statistically non-significant increase in breast cancer risk of 16%.
Kruk, J and Aboul-Enein, HY. Psychological stress and the risk of breast cancer: a case-control study. Cancer Detection and Prevention, Vol. 28, No. 6, 2004, pp. 399-408