High Stress May Cut Breast Cancer Risk
But Having Lots of Chronic Stress Still Isn't Healthy, Researchers Warn
Sept. 8, 2005 -- Women who feel stressed out may be less likely to develop breast cancer than their mellower peers, Danish researchers report in the British Medical Journal.
But the scientists aren't trumpeting the benefits of stress. They warn that feeling stressed can take a big toll on the body.
If that sounds like a mixed message, don't fret. Here is the scientists' theory: High stress levels crank up production of stress hormones. Over time, that throws off estrogen production -- a growth factor for some breast cancers. Less estrogen means less breast cancer, write Naja Rod Nielsen and colleagues.
Nielsen is a student and research assistant at Denmark's National Institute of Public Health.
Nielsen's team looked at data from more than 6,600 women in Denmark. The women had enrolled in a long-term study of heart health.
When the heart study started, the women were about 50 years old. They rated the intensity and frequency of their tension, nervousness, impatience, and sleeplessness.
What upsets one person may not bother another. That's why the researchers asked the women about feelings, not sources of stress.
The women were followed for up to 18 years. During that time, 251 women had their first breast cancer diagnosis.
High Stress, Breast Cancer
Women who reported high stress levels at the study's start were 40% less likely to be diagnosed with breast cancer during the study than those who had reported low stress levels.
That was especially true of women who were receiving hormone therapy. For those women, every increase on a six-point stress scale brought an 8% drop in breast cancer risk, write the researchers.
The jury is still out on how stress affects breast cancer risk. The Danish findings contradict several other studies, note Nielsen and colleagues. They add that one of those studies focused on extremely stressful life events, not day-to-day stresses.
"A greater risk of breast cancer associated with stressful life events is not necessarily in contrast with a lower risk of breast cancer associated with daily stress," write Nielsen's team.