Not all women have the same risk of developing breast cancer over a lifetime. Certain factors increase a person’s risk and some have a bigger impact than others. However, having several risk factors does not mean a person will get the disease. Likewise, having a few risk factors does not mean that an individual will never develop it. “A risk factor is anything that increases your chances of getting a disease, such as breast cancer. But having a risk factor, or even many, does not mean that you are sure to get the disease,” explains the American Cancer Society (ACS).
Being a woman is the strongest risk factor for breast cancer. Many other important risk factors are beyond a person’s control, such as age, family history, genetic factors and medical history, among others. However, some risk factors can be controlled or modified and they include lack of physical activity and alcohol consumption. According to health experts, it is important to be aware of the risk factors and discuss them with a doctor, which may enable a person to make more informed lifestyle and healthcare decisions.
Risk factors you cannot change
Gender: The disease is about 100 times more common among women than men.
Getting older: The risk for breast cancer increases with age and most breast cancers are diagnosed in women 55 and older.
Family history of breast cancer: Overall, about 15% of women with breast cancer have a family member with this disease. Women who have close blood relatives with breast cancer have a higher risk. This includes having a first-degree relative such as a mother, sister, or daughter, which nearly doubles a woman’s risk and having 2 first-degree relatives increases the risk about 3-fold. Multiple family members on either the mother’s or father’s side of the family who have had breast or ovarian cancer is also a risk factor. Having a first-degree male relative with breast cancer also raises a woman’s risk.
Genetic mutations: An important reason for an elevated risk is inherited changes (mutations) to certain genes, such as BRCA1 and BRCA2. Women who have inherited these genetic changes are at higher risk of breast and ovarian cancer. About 5% to 10% of breast cancer cases are thought to be hereditary, meaning that they result directly from gene changes passed on from a parent. Other gene mutations can also lead to inherited breast cancers, but they are rarer and most of them do not increase the risk of breast cancer as much as the BRCA genes. “On average, a woman with a BRCA1 or BRCA2 gene mutation has up to a 7 in 10 chance of getting breast cancer by age 80. This risk is also affected by how many other family members have had breast cancer. It goes up if more family members are affected. Women with one of these mutations are more likely to be diagnosed with breast cancer at a younger age, as well as to have cancer in both breasts,” says ACS.
Early periods and late menopause: Women who have had more menstrual cycles because they started menstruating early, especially before age 12, and starting menopause after age 55 are risk factors. This is because they expose women to the hormones estrogen and progesterone longer, raising their risk of getting breast cancer.
Personal history of breast cancer: A woman with cancer in one breast has a higher risk of developing new cancer in the other breast or another part of the same breast in the future. This is not the same as a recurrence or return of first cancer. While the risk is low overall. It is even higher for younger women with breast cancer.
Non-cancerous breast diseases: Some non-cancerous breast diseases or conditions such as atypical hyperplasia (when cells appear abnormal) or lobular carcinoma in situ or ductal carcinoma in situ are associated with a higher risk of getting breast cancer.
Having dense breast tissue: Breasts are made up of fatty tissue, fibrous tissue and glandular tissue. Dense breasts have more fibrous and glandular tissue than fatty tissue, which can sometimes make it hard to see tumors on a mammogram. Women with dense breasts, as seen on a mammogram, have a higher risk of breast cancer.
Radiation exposure: Women who have radiation to the chest as part of treatment for another cancer (such as Hodgkin’s disease) have a considerably higher risk for breast cancer, especially if they underwent radiation during adolescence. “The risk is highest for women who had radiation as a teen or young adult when the breasts are still developing. Radiation treatment in older women (after about age 40 to 45) does not seem to increase breast cancer risk,” write researchers.
Women who took diethylstilbestrol (DES): Between 1940 and 1971, some women were given this drug called DES because it was thought to prevent or lower their chances of miscarriage. These women have a slightly increased risk of developing breast cancer. Women whose mothers took DES during pregnancy may also have a slightly higher risk of breast cancer.
Risk factors you can control
Lack of exercise: A sedentary lifestyle with little physical activity can increase your risk for breast cancer. Evidence is growing that regular physical activity reduces breast cancer risk, especially in women past menopause. “Exactly how physical activity might reduce breast cancer risk isn’t clear, but it may be due to its effects on body weight, inflammation, hormones, and energy balance. The ACS recommends that adults get 150 to 300 minutes of moderate-intensity or 75 to 150 minutes of vigorous-intensity activity each week (or a combination of these). Getting to or going over the upper limit of 300 minutes is ideal,” suggest guidelines.
Being overweight or obese: This has been linked to breast cancer risk, especially for women after menopause, but the relationship is complicated. It may be that risk is increased in women who gain weight in adulthood but not in those who have been overweight since childhood.
Taking hormones: Some forms of hormone replacement therapy (those that include both estrogen and progesterone) taken during menopause can raise the risk for breast cancer when taken for more than five years. Certain oral contraceptives (birth control pills) also have been found to raise breast cancer risk.
Reproductive history: Having the first child after age 30, and never having a full-term pregnancy can raise breast cancer risk. Many studies suggest that breastfeeding may slightly lower breast cancer risk, especially if it is continued for a year or more. But this has been hard to study, especially in countries like the US, where breastfeeding for this long is not common.
Drinking alcohol: Women who drink alcohol have an increased risk of breast cancer, compared with women who do not drink, and the risk rises with the number of drinks consumed. “Women who have 1 alcoholic drink a day have a small (about 7% to 10%) increase in risk compared with non-drinkers, while women who have 2 to 3 drinks a day have about a 20% higher risk than non-drinkers. Alcohol is linked to an increased risk of other types of cancer too,” according to ACS.