This'll frost a few pumpkins

It turns out that chronic stress reduces your risk of breast cancer. This is based on a prospective cohort study, so it's about the best you can do without deliberately stressing out thousands of women for 20 years as an experiment. The study is very methodologically sound and shows a clear dose-response relationship. The more stress, the less cancer.

The reason appears to be that chronic stress affects your hormonal balance, and among other consequences reduces estrogen levels, which in turn reduces breast cancer risk -- and by a considerable amount, I might add. Women with high levels of stress had only 60% the breast cancer risk of women with low levels.

But don't go out and marry a lazy, demanding jerk or invite your unemployed 24-year-old video game-addicted son to move back in. The authors point out that stress is bad for you in other ways, particularly cardiovascular risk. Don't forget that heart disease kills more women than breast cancer, even though it doesn't seem to get as much publicity or have the same political constituency. The lesson, if there is one, is that there isn't any one cause for health and disease, no matter what the Maharishi tells you. We're complicated.