High stress cuts breast cancer risk, study finds

Scientists speculate on role of estrogen

LONDON— Women who say they live highly stressful lives are at less risk than others of developing breast cancer for the first time, according to research in the British Medical Journal.

Scientists from Denmark drew their conclusions after studying 6,689 women over a period of 18 years, and speculated that it may be because daily stress suppressed production of estrogen, which is a breast cancer risk factor. “ Prolonged low- key stress of everyday life results in a persistent activation of stress hormones, which may impair estrogen synthesis and may therefore be related to lower risk of breast cancer,” they wrote. However, they pointed out this link was an untested hypothesis that deserved follow- up investigation. Not only did the researchers from the National Institute of Public Health in Copenhagen find a lower incidence of primary breast cancer among stressed women, they found the higher the daytoday stress levels the lower the risk. The women in the study were ranked on a scale of one to six on their “ perceived stress.” For each step up the sixpoint scale, the researchers noted an 8 per cent reduction in risk of first- instance breast cancer.

Stress was not defined in the study beyond being the kind of daily stress the women themselves perceived. Previous studies have found major stressful life events — the death of a partner, for instance — may increase the likelihood of breast cancer. The authors warned that stress was far from a key to good health, noting that “ more women in the high- stress group died during follow- up than in the medium or low-stress groups. Also, high daily stress levels have been associated with increased risk of other potential killers like heart disease.