What's Your Risk for Breast Cancer?
By Emily Albright, M.D.
Board Certified General Surgeon
Saint Anthony's Physician Group
Knowing your risk of any disease is presumably the first step toward taking action. And there are clear indications that significant numbers of women are becoming more involved with their personal health.
Breast cancer is the most commonly diagnosed cancer in women and, after lung cancer, the one most likely to lead to death. The death rate from breast cancer has fallen since 1990, however, and more tumors are being found at an earlier stage. With better understanding of risk factors, you have the potential to improve your chances against a potentially devastating disease.
AGE, FAMILY HISTORY: The number one risk factor for breast cancer is age. If you’re age 40, your risk of developing breast cancer lumps in the next 10 years is 1 in 48. If you’re 60, that risk has jumped to 1 in 26.
Family history is also important. If your mother, sister or daughter has breast cancer, your risk is double that of other women. And if you have more than one close relative with breast cancer, your risk is increased five-fold. In a few cases, family history is associated with a gene mutation such as BRCA1 or BRCA2 that substantially increases risk.
While you can’t change your age, genetics or family history, you can use these risk factors to guide your decisions concerning screening. Except for women with other risks, breast cancer is rarely diagnosed before age 40. That’s why, for women of average risk, the American Cancer Society recommends regular mammograms starting at age 40 and continuing as long as a woman is in good health.
The declining death rate from breast cancer is generally attributed to use of mammography combined with improved treatment. At any age, of course, a woman should learn about breast self examination and perform it at least monthly to look for lumps and changes. Breast self examination should be supplemented by clinical examinations in a doctor’s office once every three years before age 40 and yearly after that time.
BREAST DENSITY: Breast density may be one of the most important risk factors for breast cancer. In fact, except for age and genetic factors such as BRCA1 and BRCA2, breast density may be the strongest risk.
Dense breasts have less fat and more glandular material. Young women, who have a low risk, tend to have denser breasts, but so do some older women, particularly those who take hormone replacement therapy or have a genetic tendency.
The link between dense breasts and increased risk is not well understood, but early tumors are also more difficult to detect in dense breast tissue. While you have no control over whether your breasts are dense, you can be more vigilant if they are and consider asking your doctor about screening with digital mammography, MRI or ultrasound.
WEIGHT GAIN during adult life, and particularly after menopause, is a risk factor that you can control. A weight gain of 20 to 30 pounds after age 18 is associated with a 40 percent increased risk compared to a weight gain of five pounds or less. The theory is that fat cells stimulate production of estrogen, keeping the hormone in circulation even after menopause. One study found that women taking hormone therapy did not have the same risk associated with weight gain, presumably because the external source of hormones was greater than that of the fat cells.
PHYSICAL ACTIVITY: Getting regular exercise is one of the best ways of avoiding weight gain. It also helps regulate estrogen, insulin and insulin-like growth factors, all of which have been linked to the growth of cancer cells.
Studies have found that women who engage in moderately intense or vigorous exercise at least three or four hours a week are 20 to 30 percent less likely to develop breast cancer. The American Cancer Society recommends 45 to 60 minutes at least five days a week–a step up from what is generally recommended for good health.
FOLIC ACID, ALCOHOL: Women who have more than one drink a day of alcohol have an increased risk of breast cancer, but only if they fail to get adequate quantities (at least 500 micrograms a day) of folic acid, a B vitamin.
VITAMIN D: Women who spent considerable time outdoors in their teen years had a lower risk of breast cancer, according to one recent study. Sun exposure triggers vitamin D production in the body, and there is considerable evidence that vitamin D offers protection against breast and a number of other cancers.
Experts now realize that the recommended level of vitamin D (400 IU) is too low; 800 to 1,000 IU is best. Since dietary sources are limited, 10 to 15 minutes of unprotected exposure to the sun several days a week and/or vitamin D supplements may be prudent.
HORMONES: Estrogen has a role in the development of breast cancer. As a result, women taking birth control pills have a slightly increased risk that disappears within 10 years after stopping use, according to data from the Nurses’ Health Study. Long-term use of combined hormone replacement therapy has a similar effect that drops back to normal within five years, according to the Women’s Health Initiative.
OTHER FACTORS: Increased intake of fruits and vegetables has been linked to a decreased risk. Although the evidence is not as strong as once believed, there are numerous other health benefits to be gained from eating fruits and vegetables.
Soy, vitamin E, vitamin C and selenium are often touted as substances capable of lowering breast cancer risk. The evidence, however, is too weak to make a recommendation either way.
Taking a preventive approach to breast cancer still has its frustrations. About three quarters of breast cancers occur in persons with no known risk factors. If you know your personal risks, there’s no reason for either anxiety or self assurance. With exercise, weight control, healthy habits and regular screening, you can improve your odds.