As reported by The New York Times, January 21, 2009.

Reducing Your Risk for Breast Cancer

By Roni Caryn Rabin

Go for regular checkups, do breast self-exams and get your mammograms on time, and chances are you’ll detect breast cancer early on, when it is most treatable. But what about prevention? Short of radical surgery, are there steps you can take to reduce the risk?

Turns out there are.

True, immutable factors like genetics, a family’s medical baggage and just being born female determine much of the risk of breast cancer. And, as with all cancers, that risk increases with age: a 30-year-old woman’s chances of developing breast cancer over a 10-year period are less than half of 1 percent, or 1 in 234, while a 60-year-old has a 3.5 percent risk, or 1 in 28. (The often-heard “one in eight” figure refers to the lifetime risk that women face.)

But there is now solid evidence that lifestyle can play a role as well. Choices that have an effect include how much alcohol a woman drinks (none is best), the amount of physical activity she gets (the more the better) and whether she takes hormones (the less the better). Doctors also urge women to keep their weight down, as obesity increases the risk of developing breast cancer during the postmenopausal years.

“Breast cancer is a disease of how much estrogen you have in your body,” said Heather Spencer Feigelson, strategic director of genetic epidemiology for the American Cancer Society, and these seemingly disparate factors — alcohol, physical activity and hormone pills — affect levels of estrogen and other hormones.

“There are things you can’t change, like when you got your first period, or your family history,” said Dr. Carolyn D. Runowicz, director of the Carole and Ray Neag Comprehensive Cancer Center at the University of Connecticut Health Center in Farmington, Conn., referring to two well-known risk factors, early menstruation and having a close relative with breast cancer. “But you can change a lot about you. Empower yourself with knowledge and information.”

Know your family’s medical history — but even if there is no history of breast cancer, don’t be complacent. Consult a genetic counselor if you are concerned about your family history, and inquire about being tested for the genetic mutations that increase breast cancer risk (more common among Ashkenazi Jews). Do not forget that breast cancer genes come from both sides of the family, not just your mother’s.

Among relatives, “the special red flags” are premenopausal breast cancer, bilateral breast cancer (cancer that appears in both breasts) and ovarian cancer, said Dr. Larry Norton, deputy physician in chief of breast cancer programs at Memorial Sloan-Kettering Cancer Center. But even if no one in the family had breast cancer, that is no guarantee that you are safe, said Dr. Runowicz; in fact, only 10 percent of breast cancer patients have a family history.

Cut down on alcohol, or avoid it altogether. When it comes to breast cancer, studies have been pretty consistent: there is no safe amount of alcohol. Even one glass of wine a day can increase your risk slightly, and the risk climbs with each additional drink. “This is something you can control,” said Jasmine Q. Lew, a student at the Pritzker School of Medicine at the University of Chicago who recently completed a National Institutes of Health study that is one of the largest on the subject. “Women can choose not to drink.”

Exercise, exercise, exercise. Obesity after menopause increases the risk of breast cancer, so try to keep your weight down. But exercise is beneficial regardless of weight, and even a small amount of physical activity may be helpful. “Women who are overweight and exercising are at lower risk than those who are overweight and not exercising; women who are lean and exercising are at lower risk than women who are lean but not exercising,” Dr. Feigelson said. Risk drops with increased hours and strenuousness of exercise, and studies have found that women who do an average of three hours of strenuous exercise a week reduce their risk of breast cancer by 20 percent.

Breast-feed if you can. Early menstruation, late menopause, postponing pregnancy and never having gone through a full-term pregnancy increase the risk of breast cancer, but those factors cannot be changed easily. If you do have a baby, however, you may want to breast-feed, and the longer the better; studies have found that breast-feeding reduces the risk of breast cancer.

Try not to take combined hormone therapy. The recommendation for all hormone therapy is to take the lowest dose for the shortest period necessary. A Women’s Health Initiative study found a slightly higher risk for breast cancer among women who took estrogen with progestin after menopause, and a drop in breast cancer diagnoses since then has been attributed to the fact that many women quit using hormones. (In the same study, women on estrogen-only therapy, which is used by those who have had hysterectomies, did not have a higher breast-cancer risk.) A woman who has recently used birth control pills is also at greater risk; Dr. Norton urges women to find alternative contraceptive methods and avoid so-called natural or herbal hormones as well.

Have regular mammograms, but if you have very dense breast tissue or are at high risk of breast cancer for other reasons, insist on an M.R.I. as well. Having high breast-tissue density can drastically raise your risk of developing breast cancer, as does finding atypical hyperplasia, or abnormal cell growth, which is confirmed by a biopsy. After a mammogram, discuss the results with your physician. “Everyone just wants to hear that it’s negative,” Dr. Runowicz said. But important information can be gleaned even from a negative screening, she said. “Learn about your breast density. If a biopsy shows hyperplasia, your doctor can put you on a chemoprevention program.”

Become familiar with your personal risk factors. Your breast cancer risk could be higher than normal if you are above average height, upper middle class (probably related to the tendency to postpone childbearing and having fewer children), never had a full-term pregnancy or you had children after age 30, or if you ever had endometrial, ovarian or colon cancer or ever had high-dose radiation to the chest, your risk for breast cancer could be higher than average.