Breast cancer risk factors

pink paper dolls with breast cancer ribbonLearning what causes cancer and what the risk factors are for different types of cancer can be the first step in cancer prevention. Different cancers have different risk factors. While having these factors doesn’t mean you will ever develop cancer, they can be a good indicator and a motivator to get screened and take preventative measures.

“Breast cancer is the most common cancer among women, excluding skin cancer. It accounts for more than 1 in 4 cancers diagnosed in women in the U.S.,” says Sujata Jere, M.D., an ADC family practitioner. “In 2007, there were about 40,000 deaths from breast cancer in the U.S.”

Inherent risk factors

There are risk factors for breast cancer that are inherent, and there are some lifestyle factors that you can control. The main risk factor is simply being a woman. Because women’s breast cells are exposed to the hormones estrogen and progesterone, women are about 100 times more likely than men to develop the disease.

Your risk of breast cancer increases as you age — one in eight invasive breast cancers are found in women under 45, while two out of three invasive breast cancers are found in women 55 and older. White women are slightly more likely to develop breast cancer than African-American women, but African-American women are more likely to die from the disease. Women with a personal history of breast cancer in one breast are three to four times more likely to develop a new cancer in the other breast or in another part of the same breast.

“Up to 10 percent of breast cancers are thought to be hereditary, resulting from gene mutations inherited from either parent,” says Dr. Jere. “Women with a close blood relative who has had breast cancer also have a higher risk.”

Lifestyle-related risk factors

Some factors that increase the risk of breast cancer are linked to cancer-causing influences in the environment, while others are related to behavior. Some of these factors influence risk more than others, and your risk can change over time due to changes in lifestyle or aging. According to the American Cancer Society (ACS), lifestyle factors that have been shown to increase the risk of developing breast cancer include:

  • Not having children, or having them late in life. Women who don’t have children or who have them after age 30 have a slightly higher breast cancer risk, possibly because pregnancy reduces a woman’s total number of menstrual cycles in her lifetime.
  • Recent oral contraceptive use. Studies have found that women who use birth control pills have a slightly greater risk of breast cancer than women who have never used oral contraceptives. This risk seems to decline once the use of these pills is stopped.
  • Post-menopausal hormone therapy (PHT). Commonly known as hormone replacement therapy (HRT), this treatment helps relieve menopausal symptoms and helps prevent osteoporosis by using estrogen and progesterone together or separately. Long-term use (several years or more) may increase the risk of breast cancer and the chances of dying of breast cancer if the disease does develop.
  • Not breast-feeding. Some studies suggest that breast-feeding may slightly lower breast cancer risk. Breast-feeding also reduces a woman’s total number of menstrual cycles.
  • Alcohol use. The risk of developing breast cancer increases with the amount of alcohol consumed.
  • Being overweight or obese. Being overweight increases breast cancer risk, especially for women after menopause.
  • Lack of physical activity. A sedentary lifestyle increases breast cancer risk. The ACS recommends 45 to 60 minutes of exercise at least five days a week.


The ACS recommends that women begin having yearly mammograms at age 40. An annual mammogram is widely accepted as the best way to discover breast cancer at its earliest stages, helping to reduce mortality from the disease. It may be beneficial to begin screening earlier if you are at high risk for breast cancer. Talk to your doctor to help determine the right screening program for you.

“For women who have very high risk for breast cancer, including those who have a first-degree relative with cancer or who have inherited a mutated gene, you should also add a yearly MRI to your screening process,” says Dr. Jere. “An MRI should be in addition to the mammogram, not a substitute.”

Breast cancer is second only to lung cancer in cancer death among women, but the mortality rate has been decreasing. Experts say this is most likely due to improvements in care and early detection. The Susan G. Komen Foundation says that 15 to 30 percent of breast cancer deaths in women over 40 could be prevented by timely screening mammograms.

“The most important thing to remember is that having a risk factor, or even several, doesn’t necessarily mean you will get the disease,” says Dr. Jere. “Most women who have one or more risk factors never develop breast cancer, and many women with breast cancer don’t have any of the risk factors. Get screened, take care of your general health, and provide your doctors with a complete family history. Those are the things that will be your best defense against cancer.”