Six or more hours per week of strenuous recreational activity may reduce the risks of invasive breast cancer by 23%, according to researchers from the University of Wisconsin Paul P. Carbone Comprehensive Cancer Center (UWCCC). Their report in a recent issue of Cancer Epidemiology Biomarkers & Prevention, based on a survey of over 15,000 women, shows that exercise has a protective effect against invasive breast cancer throughout a woman's lifetime. The results provide further evidence that for most women, physical activity may reduce the risk of invasive breast cancer, the researchers concluded.
Detailed Phone Interviews
To gain further insights into the mechanisms of risk reduction for breast cancer, the researchers investigated the relationship between physical activity and breast cancer risk in a population-based case control study in Massachusetts, New Hampshire, and Wisconsin.
During structured telephone interviews, the researchers questioned 7,630 women without breast cancer, 1,689 survivors of in situ, or noninvasive, breast cancer and 6,391 survivors of invasive breast cancer, all between the ages of 20 and 69. They asked detailed questions about physical activity, occupation, family history of breast cancer, menopausal status, and body mass index.
According to the researchers, women who exercised had a reduced risk of developing invasive breast cancer provided they didn't have a family history of breast cancer. This reduction in risk was apparent whether the physical activity took place early in life, in the postmenopausal years, or in the recent past.
"A woman's hormone levels naturally fluctuate throughout her life, and we have found that exercise likely offers protection against breast cancer regardless of a woman's stage in life," said Brian Sprague, a UWCCC research assistant and lead author of the study. "The take-home message for women should be that it is never too late to begin exercising."