Researchers say there may be a silver lining for women who have to deal frequently with the irritation of hot flashes. A study from the Fred Hutchinson Cancer Research Center in Seattle found a correlation between lowered breast cancer incidence and the physical symptoms of menopause.

Dr. Christopher Li said the most annoying types of menopause symptoms were among the most strongly linked to lower breast cancer risk.

"In particular we found that women who experienced more intense hot flushes - the kind that woke them up at night - had a particularly low risk of breast cancer," he said.

Li and his fellow researchers postulate that there is a connection between the body's levels of estrogen and progesterone - hormones which, they say, are important factors in the development of some breast cancers - and the tapering-off of their production in the ovaries of menopausal women.

The full results of the study are due to be published in the February edition of Cancer Epidemiology Biomarkers and Prevention.

Experts say the best defense against breast cancer is still early detection, and urge women to have frequent mammograms as they enter middle age.