Lifetime physical activity and risk of breast cancer.

We conducted a case-control study of 394 women with breast cancer and 788 control women (91% response) to investigate the association of lifetime physical activity with mainly menopausal breast cancer risk. After controlling for potential confounders, the odds ratios (95% confidence intervals) for increasing quartiles of lifetime physical activity were 1.00 (referent), 0.91 (0.60-1.37), 0.91 (0.60-1.39), and 1.10 (0.73-1.67), respectively; P, trend = 0.47. We also separately examined physical activity at ages 12-18, 19-34, 35-49 and > or =50 years; no significant trends were observed in any age group. These data do not support a role of physical activity in preventing breast cancer. Copyright 2001 Cancer Research Campaign