Breast Cancer Risk Factors

Posted: March 1, 2005

Anything that increases your chance of getting a disease is called a risk factor. Risk factors for breast cancer include:

• Older age
• Early age at first menstrual period
• Older age at first birth or never having given birth
• A personal history of breast cancer or benign (non-cancer) breast disease
• A mother or sister with breast cancer
• Treatment with radiation therapy to the breast/chest
• Breast tissue that is dense on a mammogram
• Hormone use (such as estrogen and progesterone)
• Drinking alcoholic beverages
• Caucasian race

Breast cancer prevention
Many risk factors for breast cancer are modifiable, though not all can be avoided.

Tamoxifen for prevention of breast cancer: Tamoxifen is a drug that blocks the effect of estrogen on breast cancer cells. A large study has shown that tamoxifen lowers the risk of getting breast cancer in women who are at elevated risk of getting breast cancer. However, tamoxifen may also increase the risk of getting some other serious diseases, including endometrial cancer, stroke and blood clots in veins and in the lungs.

Women who are concerned that they may be at an increased risk of developing breast cancer should talk with their doctor about whether to take tamoxifen to prevent breast cancer. It is important to consider both the benefits and risks of taking tamoxifen.

Hormonal factors: Hormones produced by the ovaries appear to increase a woman’s risk for developing breast cancer. The removal of one or both ovaries reduces the risk. The use of drugs that suppress the production of estrogen may inhibit tumor cell growth. The use of hormone replacement therapy, also called hormone therapy, may be associated with an increased risk of developing breast cancer, mostly in recent users. The use of oral contraceptives may also be associated with a slight increase in breast cancer risk.

Beginning to menstruate at an older age and having a full-term pregnancy reduces breast cancer risk. Also, a woman who has her first child before the age of 20 experiences a greater decrease in breast cancer risk than a woman who has never had children or who has her first child after the age of 35. Beginning menopause at a later age increases a woman’s risk of developing breast cancer.

Radiation: Studies have shown that reducing the number of chest X-rays, especially at a young age, decreases the risk of breast cancer. Radiation treatment for childhood Hodgkin’s lymphoma may put women at a greater risk for breast cancer later in life. A small number of breast cancer cases can be linked to radiation exposure.

Diet and lifestyle: Diet is being studied as a risk factor for breast cancer. Studies show that in populations that consume a high-fat diet, women are more likely to die of breast cancer than women in populations that consume a low-fat diet. It is not known if a diet low in fat will prevent breast cancer.

Exercise, especially in young women, may decrease hormone levels and contribute to a decreased breast cancer risk.

Breastfeeding may also decrease a woman’s risk of breast cancer.

Postmenopausal weight gain, especially after natural menopause and/or after age 60, may increase breast cancer risk.

Studies suggest that the consumption of alcohol is associated with a slight increase in the risk of developing breast cancer.

Prophylactic mastectomy: Following cancer risk assessment and counseling, the removal of both breasts may reduce the risk of breast cancer in women with a family history of breast cancer.

Genetics: Women who inherit specific genes are at a greater risk for developing breast cancer. Research is underway to develop methods of identifying high-risk genes.

Source: National Cancer Institute

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