Whos At Risk - Chapter 6 Breast Cancer Whos At Risk: Cancer

Content provided by the Faculty of the Harvard Medical School

Who's at risk?

Scientists have identified a number of factors that affect a person's risk of developing breast cancer. Some of them can be controlled; others cannot.

Gender. Both women and men develop breast cancer, but women are much more likely to develop the disease, largely because their breasts undergo a complex hormonal evolution as they mature during their teens and early twenties.

Age. The risk of getting this disease rises sharply as a woman gets older. Breast cancer chiefly occurs in women who are older than 50, and despite the news headlines, it's uncommon in women under age 35, except in cases that might involve hereditary influences.

Family medical history. Vulnerability to breast cancer is heightened for any woman who has a close blood relative diagnosed with the disease. Having one first-degree relative (mother, sister, or daughter) with breast cancer approximately doubles a woman's risk. Having two first-degree relatives with breast cancer increases her risk five-fold. In a few cases, breast cancer is the direct result of a genetic mutation, such as those identified as BRCA1 and BRCA2, which is inherited from either parent, or from an interaction among other genes. Women who inherit the BRCA1 gene, for instance, have 15 times the chance of developing breast cancer as women who do not have that particular form of the gene.

Ethnic/racial background. White women are at greatest risk for the disease, but African American women are at highest risk for the disease before mid-life. Latino and Asian American women have the lowest risk of breast cancer. If you are Jewish, and especially if you are of Ashkenazi descent (from Central or Eastern Europe), you have an increased chance of developing breast cancer because of the much greater likelihood that you have inherited a BRCA1 or BRCA2 gene mutation.

Menstrual periods and hormone exposure. Anything that increases your long-term exposure to ovarian hormones has an influence on breast cancer risk. Early menstruation, late menopause, and late age of first pregnancy or no pregnancy can slightly increase a woman's risk of developing breast cancer.

Prolonged treatment with hormone therapy after menopause increases breast cancer risk. The highest risk is related to the combination of estrogen and a progestin (progesterone).

Tissue changes in the breast. Some forms of benign breast disease increase your risk of breast cancer. Lobular carcinoma in situ is a noncancerous tumor in the lobules, the milk-producing glands of the breast, which does not penetrate the gland walls. Atypical ductal hyperplasia is the name for microscopic changes in the breast. Both of these noncancerous conditions increase a woman's risk of developing breast cancer.

Previous breast cancer. If you have already had breast cancer in one breast, you are two to four times more likely to develop it in your other breast. Likewise, if you have had colon or ovarian cancer, your risk for breast cancer is slightly increased.

Previous radiation treatment. Women who've had high doses of radiation to the chest before age 30 - usually for Hodgkin's disease - have a significantly increased risk for breast cancer as adults. Therefore women who received high-dose radiation therapy before age 30 should have yearly mammograms and breast exams. These cancers usually are first noted 10 to 15 years after the radiation therapy was completed. On the other hand, radiation received after age 30 does not significantly increase a woman's risk of developing breast cancer.

Height. It may seem ridiculous that your height could affect your risk for breast cancer. But tall women are at increased risk for the disease, for reasons that remain unclear.

Alcohol. A moderate link exists between the use of alcohol and breast cancer. Wine, beer, and hard liquor can elevate the amount of estrogen in the blood, and anything that increases long-term exposure to estrogen can increase breast cancer risk. According to studies, having one drink a day or more appears to modestly increase breast cancer risk.

Weight. The influence of weight on the risk of breast cancer depends on several factors, including your age and whether you take hormone replacement therapy. But, in general, avoiding weight gain during the adult years can help reduce breast cancer risk.

Sedentary lifestyle. A few studies have looked at the relationship between physical activity and breast cancer risk, but the results so far have been inconsistent. Some studies show a substantial risk reduction, some turn up evidence of a moderate protection, and others show no effect. Although the link between exercise and a lower risk of breast cancer remains inconclusive, experts believe that the benefits of exercise in controlling weight gain (which increases risk) and other indirect evidence is sufficient to recommend regular exercise as a preventive measure.

Last updated:	May 01, 2008