To reduce risk, watch diet and alcohol intake

Some risks factors for breast cancer you can’t control. But the American Cancer Society offers this list of lifestyle factors that may affect — positively or negatively — your risk for breast cancer.

Having children

Women who have not had children or who had their first child after age 30 have a slightly higher breast cancer risk. Having many pregnancies and becoming pregnant at an early age reduces breast cancer risk.

Birth control

Recent oral contraceptive use: Studies have found that women using oral contraceptives (birth control pills) have a slightly greater risk of breast cancer than women who have never used them. Over time, this risk seems to go back to normal once the pills are stopped.

Hormone therapy after menopause

Hormone therapy using estrogen (often combined with progesterone) has been used for many years to help relieve symptoms of menopause and to help prevent osteoporosis (thinning of the bones). Earlier studies suggested it might have other health benefits as well, but those benefits have not been found in more recent, better designed studies.

Breastfeeding

Some studies suggest that breastfeeding may slightly lower breast cancer risk, especially if it is continued for 1¹⁄₂ to 2 years. But this has been a difficult area to study, especially in countries such as the United States, where breastfeeding for this long is uncommon.

Alcohol

Consumption of alcohol is clearly linked to an increased risk of developing breast cancer. The risk increases with the amount of alcohol consumed. Compared with non-drinkers, women who consume one alcoholic drink a day have a very small increase in risk. Those who have two to five drinks daily have about 1¹⁄₂ times the risk of women who don’t drink.

Being overweight  or obese

Being overweight or obese after menopause has been found to increase breast cancer risk. Before menopause your ovaries produce most of your estrogen, and fat tissue produces a small amount of estrogen. After menopause (when the ovaries stop making estrogen), most of a woman’s estrogen comes from fat tissue. Having more fat tissue after menopause can increase your chance of getting breast cancer by raising estrogen levels.

Physical activity

Evidence is growing that physical activity in the form of exercise reduces breast cancer risk. To reduce your risk of breast cancer, the American Cancer Society recommends 45 to 60 minutes of intentional physical activity five or more days a week.