Identifying breast cancer risk factors:
Combined hormone-replacement therapy – In the largest study of its kind, research by Dr. Christopher Li found that postmenopausal women who take combined estrogen/progestin hormone-replacement therapy for at least three years are four times more likely to develop various forms of lobular breast cancer. Learn more »
Exercise and weight – Dr. Anne McTiernan and colleagues have found that postmenopausal women who keep their weight in check and exercise regularly have a significantly lower risk of developing breast cancer. The multicenter study was part of a long-term national study called the Women's Health Initiative. Learn more »
Alcohol consumption – A study led by Dr. Polly Newcomb found that women who consumed 14 or more drinks per week, regardless of the type (wine, liquor or beer), faced a 24 percent increase in breast cancer compared with non-drinkers. Learn more »
Genetic susceptibility – A multicenter research study painted one of the clearest pictures yet of mutations in genes that indicate susceptibility to breast cancer—findings that could help identify women who would benefit from genetic testing. The comprehensive study tracked the prevalence of mutations in BRCA1 and BRCA2 genes in African-American and Caucasian women and examined factors, such as age at breast cancer diagnosis, that predict the likelihood of such mutations. Learn more »
Smoking – Older women who have smoked for 11 or more "pack years"—the lifetime equivalent of a pack a day for at least 11 years—face a 30 to 40 percent increased risk of developing breast cancer as compared to women who've never smoked, according to a study by Dr. Christopher Li and colleagues. What's more, the study found that long-term smokers who also take combination hormone-replacement therapy increase their odds of getting breast cancer by 110 percent. Learn more »
Breast density – A study co-authored by Dr. Emily White found that women whose breasts contain less fatty tissue were more likely to develop breast cancer than those with dense breasts that contain more fatty tissue. The findings, which were based on data collected from more than 1 million women, suggest that a woman's breast density is nearly as important as her age in determining her risk of developing the disease. Learn more »
Fetal cells: Drs. V.K. Gadi and J. Lee Nelson led a study that found cells from a fetus that persist in a woman's body long after pregnancy—a common occurrence known as fetal microchimerism–is associated with a reduction in a woman's risk of breast cancer. Learn more »
Birth control pills: Taking oral contraceptives for a year or more may increase a woman's risk of developing triple-negative breast cancer, a rare breast form of the disease. The study, led by Dr. Kathi Malone, found that women 40 and under faced a 4.2-times greater risk of developing the disease. Using contraceptives for a longer period of time and starting use at an early age further increased this risk. Learn more »