While all women are at risk for breast cancer, particularly as they get older, there are basic strategies for reducing the chances that you will get the disease – or increasing the likelihood that if you do develop breast cancer, it will be detected at an early stage when treatment is likely to be successful. Because each woman has her own set of risk factors, specific strategies may differ: For example, a woman with an inherited mutation in one of the BRCA genes has significantly greater risk than a woman with a direct family history of breast cancer but no inherited mutation, or a woman found to have atypia or LCIS on a biopsy. But for all women, including those with no known risk factors, these minimum steps can help to reduce the risk:
- Perform breast self-examination regularly beginning at age 20, at the same time each month.The best time for a self-examination is 7-10 days after the onset of your menstrual period.
- Obtain a physical breast exam by a physician or other health care provider every year starting at age 40.
- Follow the recommended guidelines for mammograms.
- Exercise regularly and maintain a healthy diet.
Weight, Exercise, and Breast Cancer Risk
Being overweight or obese increases breast cancer risk, particularly after menopause. The reason is that excess fat can increase the body’s estrogen levels – in fact, it is the main source of estrogen once the ovaries stop producing the hormone in postmenopausal women – and estrogen can stimulate the growth of breast cancer cells. Studies have shown that women who have gone through menopause and are obese have about a 30% increased risk of developing breast cancer. Significant weight gain after menopause (more than 22 pounds) increases the breast cancer risk by 18%.
How do you know whether you are overweight? Your height and weight are used to calculate your body mass index (BMI). You are at your ideal body weight when your BMI is between 18 and 24.9. A BMI between 25 and 29.9 is considered overweight; if your BMI is higher than 30, you are classified as obese.
Fortunately, both exercise and weight loss for women who are overweight or obese have been shown to lower the breast cancer risk. Obese women who have gone through menopause and are able to lose at least 22 pounds and keep the weight off can lower their breast cancer risk by 57%. Most studies also show that vigorous physical activity – such as jogging for 45-60 minutes, five days a week or more – decreases breast cancer risk slightly. Regular less-strenuous physical activity, such as walking, may also lower the breast cancer risk.
Consult with your health care provider if you have questions about your ideal body weight and your BMI. You should always check with your health care provider before beginning any new exercise plan or diet.
Diet and Breast Cancer Risk
The link between the foods we eat and breast cancer has been difficult to determine. Some studies have suggested that women who eat more fruits and vegetables (five or more servings a day) and foods that are low in saturated fat have a slightly lower risk of developing breast cancer than those who eat fewer fruits and vegetables and more foods that are high in saturated fat. Specifically, the natural vitamin antioxidants found in fruits and vegetables may decrease the risk of cancer slightly.
On the other hand, there is no evidence that taking vitamin supplements lowers cancer risk. This includes vitamin D and calcium supplements, although a few studies have suggested that women who have the lowest blood levels of vitamin D may be at slightly increased risk of developing breast cancer. Also unproven is the link between eating more tofu and foods containing soy protein – which may have some estrogen-like effects – and breast cancer risk. Some have thought green tea might reduce breast cancer risk, but this has not been proven. Drinking too much alcohol, on the other hand, has been shown to increase breast cancer risk slightly.
Because no special diet or foods have been proven to reduce the risk of breast cancer, we recommend that you eat moderate amounts of a variety of different foods to maintain a healthy weight, and limit the amount of alcohol you drink. For more information on eating a healthy diet, consult your health care provider and the U.S. Department of Agriculture’s Dietary Guidelines for Americans.
Alcohol and Breast Cancer Risk
Studies suggest that consuming an average of more than one alcoholic beverage a day increases the risk of breast cancer, with the risk growing with the amount of alcohol consumed. One drink is defined as 10 grams of alcohol, which typically means a 12-ounce beer, a four-ounce glass of wine, or a shot (1.25 ounces) of hard liquor or spirits. With each drink you consume in excess of seven per week, your risk increases by about 9%. Thus, women who are currently exceeding the seven-drinks-a-week threshold can lower their risk by reducing their alcohol intake.