Medication and lifestyle may lower breast cancer risk
By Jane E. Brody
Mammography is a valuable tool for finding breast cancer when it is still confined to the breast and highly amenable to cure. But no matter how good the odds for survival may be with early detection, I’m quite certain women would rather not develop breast cancer in the first place.
Yet, even though 1 woman in 8 will eventually receive a breast cancer diagnosis, only a minority currently take advantage of the well-established lifestyle measures for reducing chances of developing the disease, and far fewer take medications that can help prevent it in women at higher than average risk.
Part of the problem may well be the confusion wrought by periodic reports of conflicting evidence for what raises — or lowers — a woman’s chances of developing breast cancer, ranging from the drugs she uses to the foods and beverages she consumes. Another inhibiting factor is the limited amount of time doctors can devote to assessing a woman’s risk of breast cancer and explaining the complex trade-offs involved in breast cancer prevention.
In the latest report published in JAMA, experts at the University of California, San Francisco, reviewed compelling evidence for two classes of drugs normally prescribed following breast cancer treatment that can also help prevent cancer in some women not yet affected by this disease. One class consists of two drugs, tamoxifen and raloxifene, that inhibit the action of estrogen in selective tissues. The other consists of three aromatase inhibitors, anastrozole, exemestane and letrozole, that reduce the levels of circulating estrogen that could stimulate the growth of estrogen-sensitive breast cancers.
Whether a woman might consider such drugs depends in part on lifestyle measures and medical history. Although some women may choose to ignore existing evidence and continue to do what they enjoy regardless of the associated risk, experts say women should at least be able to weigh their chosen behaviors against a raised breast cancer risk. Their decisions should also consider their personal health history and the ailments that run in their families to which they too may be susceptible.
Consumption of alcohol is a classic example. Even a small amount of alcohol — less than one drink a day — can raise breast cancer risk, and the more a woman drinks, the greater her chances of developing this disease. A friend recently treated for an early-stage breast cancer quit drinking wine, which resulted in weight loss that may also reduce her risk of a new or recurring breast cancer.
On the other hand, moderate consumption of alcohol, and wine in particular, is associated with a reduced cardiovascular risk, so if heart disease figures more prominently than cancer in your family, you may decide to have that daily glass of wine. With smoking, however, there is no health benefit, only risk — to your breasts as well as every major organ and your life.
Another modifiable breast cancer hazard is being overweight, especially after menopause, when body fat becomes the major source of cancer-promoting hormones. The good news here is that the two measures that can help you lose excess weight — a healthy diet and regular physical activity — also protect against breast cancer and reduce the risk of heart disease.
Strive for a mostly plant-based diet of vegetables, fruits, whole grains, beans and nuts; healthy sources of fats like olive and canola oil; and fish in lieu of red meat. And include a weekly minimum of 2 1/2 hours of moderate physical activity, or 75 minutes of vigorous activity, plus strength training twice a week.
Alas, two long-known protective factors — early childbearing (in the teens and 20s) and prolonged breastfeeding — run headlong into the life goals of many modern women who seek graduate degrees and professional advancement, as well as young women financially unable to support a family.
Many older women run into another confusing and controversial decision: whether and for how long to take hormone therapy to counter life-disrupting symptoms of menopause. Barring an earlier history of breast cancer, current advice for women who have not had a hysterectomy is to take combination hormone therapy (that is, estrogen and a progestin) for as short a time as needed to control symptoms but no longer than a few years.
A recent study, published July 28 in JAMA, described the long-term effects on breast cancer risk among 27,347 postmenopausal women randomly assigned to take hormone replacement or not. The authors, led by Dr. Rowan T. Chlebowski at UCLA Medical Center, reviewed the health status of the participating women more than two decades later.
Among the 10,739 women who had no uterus and could safely take estrogen alone (progestin is typically added to prevent uterine cancer), menopausal hormone therapy significantly reduced their risk of developing and dying from breast cancer. However, among the 16,608 women with a uterus who took the combination hormone therapy, breast cancer incidence was significantly higher, although there was no increased risk of death from the disease.
In commenting on these results, Dr. Christina A. Minami, a breast cancer surgeon at Brigham and Women’s Hospital, and Dr. Rachel A. Freedman, an oncologist at Dana-Farber Cancer Center, wrote that the new findings “are unlikely to lead to the use of hormone therapy for the sole purpose of breast cancer risk reduction.”
But Freedman said, “If I’m counseling a patient who’s really miserable with menopausal symptoms and is a candidate for estrogen only, these findings are reassuring that her breast cancer risk will not be any higher over time.”
Then there’s the possibility of taking a daily drug to suppress a potential breast cancer in high-risk women who have not yet had the disease. Dr. Jeffrey A. Tice, an internist at the University of California, San Francisco, suggested that women’s doctors use one of the several risk assessment calculators to determine how likely the patient might be to develop breast cancer within the next five or 10 years.
The U.S. Preventive Services Task Force concluded that the benefits of medication outweigh the risks for postmenopausal women with a 3% or greater chance of receiving a breast cancer diagnosis within five years.
Starting at age 40, younger women with a strong family history of breast cancer and those who have had precancerous findings on a breast biopsy should consider preventive drug therapy, Tice and Yiwey Shieh suggested in JAMA. Tice said women in the top 5% of breast cancer risk for their age might also evaluate the benefit of preventive therapy and its possible risks, which can include blood clots or bone loss, depending on which drug is used.
“Five years of therapy can reduce their breast cancer risk for up to 20 years,” he reported.