While stress has been linked to a woman’s risk of developing breast cancer, having an overly stressful job does not appear to do so, new study findings show.

Overall, women who rated the amount of stress they faced at work as “severe” were no more likely to develop breast cancer than women who said they dealt with “minimal” stress at work.

Although work is only one aspect of life that can cause stress, “it should be reassuring for the general audience that our findings do not support job stress to be associated with a higher breast cancer risk among women,” Dr. Eva S. Schernhammer of Brigham and Women’s Hospital and Harvard University in Boston, Massachusetts, told Reuters Health.

Previous research has suggested that life stressors may increase the risk of breast cancer, Schernhammer and her colleagues note in the American Journal of Epidemiology. However, the results have not been entirely convincing, particularly since many of the studies have asked women to recall stress after they have already been diagnosed with cancer, which may cause them to overemphasize its influence.

Also, additional research shows that episodes of intense stress may inhibit tumors in people, perhaps by beefing up the immune system. In contrast, some studies have found that chronic stress may weaken the immune system, thereby increasing the risk of cancer.

To investigate further, Schernhammer and her colleagues reviewed information collected from more than 37,500 women about their workplace stress, and followed them for up to eight years, noting who developed breast cancer.

Women in so-called “active” jobs - meaning they had high workplace demands but also a lot of latitude when making decisions - were actually 17 percent less likely to develop breast cancer than women in “low-strain” jobs, where they had a lot of control over a limited number of workplace demands.

Some women also held “passive” jobs with few demands and little control over them, and “high-strain” jobs, which featured lots of demands and little control. For these categories, the chances of developing breast cancer were 10 percent and 13 percent lower, respectively, than among low-strain workers.

Schernhammer noted that workplace stress may not affect cancer risk because it does not influence certain hormones linked to breast cancer.

SOURCE: American Journal of Epidemiology, December 2004.