What Are the Risk Factors for Breast Cancer?

The chance of getting breast cancer increases as a woman ages. About 2 out of 3 women with invasive breast cancer are 55 or older when the cancer is diagnosed. Here are some risk factors to consider to determine if you should consult with your doctor about your chances of developing breast cancer.

Genetics

About 5-10% of breast cancers are thought to be linked to inherited mutations in certain genes. The most common gene changes are associated with the BRCA1 and BRCA2 genes. Women with these gene mutations have up to an 80% chance of getting breast cancer during their lifetimes. Other gene mutations may increase the breast cancer risk as well.

Family History

Breast cancer risk is higher among women whose close blood relatives have this disease. The relatives can be from either the mother’s or father’s side of the family. Having a mother, sister, or daughter with breast cancer essential doubles a woman’s risk. It’s important to note that most women (over 85%) who get breast cancer do not have a family history of the disease.

Personal History

A woman with cancer in one breast has a greater chance of developing a new cancer in the other breast or another part of the same breast. This occurrence is different from a return of the first cancer (called recurrence).

Race

White women are slightly more likely to get breast cancer than African-American women. But African American women are more likely to die of breast cancer. At least part of the reason seems to be that African-American women have faster growing tumors, but doctors don’t know why this is the case. Asian, Hispanic, and Native-American women have a lower risk of developing and dying from breast cancer.

Dense Breast Tissue

Dense breast tissue means that the breasts are comprised of more gland tissue and less fatty tissue. Women with denser breast tissue have a higher risk of breast cancer. Dense breast tissue can also make spotting problem areas on mammograms more difficult.

Certain Benign (Non-Cancer) Breast Issues

Women who have certain benign breast changes may have an increased risk of breast cancer. Some of these conditions are more closely linked to breast cancer risk than others.

Lobular Carcinoma in Situ

Women with lobular carcinoma in situ (LCIS) have a 7 to 11 times greater risk of developing cancer in either breast.

Menstrual Periods

Women who started their periods early (before age 12) or who went through menopause after the age of 55 have a slightly increased risk of breast cancer. They’ve had more menstrual periods and, as a result, have been exposed to more estrogen and progesterone.

Early Breast Radiation

Women who’ve had radiation treatment to the chest area (as treatment for another cancer) earlier in life have a greatly increased risk of breast cancer. Risk varies depending on the patient’s age during radiation. The risk as a result of chest radiation is highest if the patient endured radiation during the teenage years when the breasts were still developing. Radiation treatment after age 40 does not seem to increase breast cancer risk.

DES Treatment

In the past, some pregnant women were given the DES (diethylstilbestrol) drug, which was thought to lower their chances of miscarriage. Recent studies have shown that these women have a slightly increased risk of developing breast cancer.


Some lifestyle choices also increase the risk of breast cancer. Consider them especially if you have other risk factors.

Not Having Children or Having Children Later in Life

Women who haven’t had children, or who had their first child after age 30, have a slightly higher risk of breast cancer. Being pregnant many times and at an early age reduces breast cancer risk. Being pregnant lowers a woman’s total number of lifetime menstrual cycles, which may be the reason for this effect.

Not Breast-Feeding

Some studies have shown that breast-feeding slightly lowers breast cancer risk, especially if the breast-feeding lasts 1½ to 2 years. This effect could be due to the fact that breast-feeding also lowers a woman’s total number of menstrual cycles.

Recent Use of Birth Control Pills

Studies have found that women who use birth control pills have a slightly greater risk of breast cancer than women who’ve never used them. This risk seems to go back to normal gradually after a woman stops taking the pill. Women who stopped using the pill more than 10 years ago do not seem to have any increased risk.

Using Hormone Therapy After Menopause

Use of combined HT (hormone therapy that uses both estrogen and progesterone) after menopause increases the risk of developing breast cancer. It may also increase the chances of dying from breast cancer. Five years after stopping HT, the breast cancer risk seems to drop back to normal. The use of estrogen alone (ET) does not seem to increase the risk of developing breast cancer very much, if at all.

Alcohol

The use of alcohol is clearly linked to an increased risk of developing breast cancer. Women who have one drink per day have a very small increased risk. But women who have 2 to 5 drinks daily have about 1½ times the risk as women who drink no alcohol. The American Cancer Society suggests a one drink per day limit.

Being Overweight or Obese

Being overweight or obese increases the risk of breast cancer, especially in women post-menopause or if the weight gain took place during adulthood. The risk seems to be higher if the extra fat sits around the waist.