Each year, more than 190,000 American women and men are diagnosed with breast cancer. No one knows if or when breast cancer will develop, but understanding the risk factors for breast cancer may help you take preventive measures to reduce the likelihood of developing the disease.What causes breast cancer?
Breast cancer is caused when the DNA in breast cells mutate or change, disabling specific functions that control cell growth and division. In many cases, these mutated cells die or are attacked by the immune system. But some cells escape the immune system and grow unchecked, forming a tumor in the breast.
While the exact cause of a person’s breast cancer may be unknown, certain risk factors are strongly linked to the disease, including obesity and heavy alcohol use. Also, those who have inherited mutations in their BRCA1 and BRCA2 genes have a high risk of developing breast cancer.Known risk factors for breast cancer include:
Aging: On average, women over 60 are more likely to be diagnosed with breast cancer. Only about 10 percent to 15 percent of breast cancers occur in women younger than 45. However, this may vary for different races or ethnicities.
Gender: Although nearly 2,000 men will be diagnosed with breast cancer each year, breast cancer is 100 times more common in women. The National Cancer Institute estimates that more than 190,000 women will be diagnosed with breast cancer annually.Genetics & family history
Family history: Having a family history of breast cancer, particularly women with a mother, sister or daughter who has or had breast cancer, may double the risk.
Inherited factors: Some inherited genetic mutations may increase your breast cancer risks. Mutations in the BRCA1 and BRCA2 genes are the most common inherited causes. Other rare mutations may also make some women more susceptible to developing breast cancer. Genetic testing reveals the presence of potential genetic problems, particularly in families that have a history of breast cancer.Body traits
Obesity: After menopause, fat tissue may contribute to increases in estrogen levels, and high levels of estrogen may increase the risk of breast cancer. Weight gain during adulthood and excess body fat around the waist may also play a role.
Not having children: Women who have had no children, or who were pregnant later in life (over age 35) may have a greater chance of developing breast cancer. Breastfeeding may help to lower your breast cancer risks.
High breast density: Women with less fatty tissue and more glandular and fibrous tissue may be at higher risk for developing breast cancer than women with less dense breasts.
Certain breast changes: Certain benign (noncancerous) breast conditions may increase breast cancer risk.
Menstrual history: Women who start menstruation at an early age (before age 12) and/or menopause at an older age (after age 55) have a slightly higher risk of breast cancer. The increase in risk may be due to a longer lifetime exposure to the hormones estrogen and progesterone.Lifestyle
A sedentary lifestyle: Physical activity in the form of regular exercise for four to seven hours a week may help to reduce breast cancer risk.
Heavy drinking: The use of alcohol is linked to an increased risk of developing breast cancer. The risk increases with the amount of alcohol consumed.Previous treatments
Birth control pills: Using oral contraceptives within the past 10 years may slightly increase the risk of developing breast cancer. The risk decreases over time once the pills are stopped.
Combined post-menopausal hormone therapy (PHT): Using combined hormone therapy after menopause increases the risk of developing breast cancer. Combined HT also increases the likelihood that the cancer may be found at a more advanced stage.
Diethylstilbestrol exposure (DES): Previous use of DES, a drug commonly given to pregnant women from 1940 to 1971 to prevent miscarriage, may slightly increase the risk of developing breast cancer. Women whose mothers took DES during pregnancy may also have a slightly higher risk of breast cancer.
Radiation exposure: Women who, as children or young adults, had radiation therapy to the chest area as treatment for another cancer have a significantly increased risk for breast cancer.
Next topic: What are the symptoms of breast cancer?