There's no one big way to reduce your risk for breast cancer, but a combination of approaches could make a difference, reports the January 2007 issue of Harvard Women's Health Watch. Here are several factors that could affect your risk:

Weight gain: Studies show that weight gain is a risk factor for breast cancer after menopause. The link is estrogen, which is believed to promote the development of breast cancer. Fat tissue converts precursors in the body into estrogen, keeping the hormone in circulation even when ovarian production stops at menopause.

Alcohol: Women who consume even a few drinks per week raise their risk for breast cancer. Scientists aren't sure why; it may be that alcohol raises estrogen levels or interacts with carcinogens.

Activity level: Exercise may help prevent breast cancer and its recurrence in a few ways, including by keeping weight down and decreasing the amount of estrogen in breast tissue.

Vitamin D: There's evidence that vitamin D helps protect against several types of cancer, including breast cancer.

Hormone use: Because lifetime exposure to estrogen is a risk factor for breast cancer, there's concern about women's use of birth control pills and postmenopausal hormones. Discuss your risk with your doctor before taking these. Chemoprevention. Taking the anti-estrogen drug tamoxifen or raloxifene may cut the incidence of breast cancer in women at increased risk for the disease.