Risk factors for breast cancer increase one’s likelihood of developing the disease. However, having one or more risk factor does not necessarily mean that one will acquire breast cancer. On the other hand, some women who do not seem to have any risk factor could still develop the disease.

Some risk factors cannot be modified, such as age or racial background. However, factors associated with a person’s behavior or lifestyle may be modified. Make some changes to these modifiable factors to reduce your likelihood of getting breast cancer.

Risk Factors for Breast Cancer

1. Being Female

Breast cancer can affect males, but it is more common among women.

2. Age

Older women are more likely to develop breast cancer, but the disease can strike at any age. In general, one’s risk for the disease increases greatly after the age 50.

3. Reproductive History

Your risk for breast cancer may vary with different stages:

• Early first period. Having your period at an early age increases your risk for breast cancer.
• Late first birth. Bearing children at an early age reduces one’s risk for breast cancer. The relative risk of developing breast cancer is estimated to increase by 3% for each year of delay
• Not breastfeeding. Breastfeeding has a protective effect on breast cancer. Studies show that women who breastfeed for longer periods have a lower likelihood for developing the disease.
• Menopause at older age. Women who experience late menopause are more likely to develop breast cancer.

4. Endogenous Hormones

Women who have higher levels of body hormones may be at increased risk for breast cancer. These hormones include estrogen, testosterone, insulin, prolactin, and insulin-like growth factor.

5. Oral Contraceptives

Women who use oral contraceptives, as well as those who have stopped using them, have a higher risk of breast cancer than women who have never used oral contraception.

6. Hormone Replacement Therapy (HRT)

The risk for breast cancer increases with current use of hormone replacement therapy compared to non-use. The risk is even greater for women who use a combination of estrogen and progestogen compared to those who use estrogen only.

7. Breast Density

Having dense breasts increases a woman’s risk for the disease. This factor is affected by one’s weight, menopause status, number of children, and genetics.

8. Breast Disease History

A history of non-malignant (not cancerous) breast disease increases a woman’s risk for cancer. Having a strong family history of breast cancer further increases one’s likelihood for developing breast cancer in the presence of benign lesions. Women who have a non-invasive type of breast cancer or a previous history of breast cancer also have a greater likelihood for developing an invasive type of cancer than women who do not have these lesions.

9. Family History

Having a mother or a sister who has breast cancer doubles your risk of developing breast cancer. The risk further increases with more relatives having the disease. A very high risk for cancer of the breast occurs in women who have a strong family history and who test positive for mutations in their breast cancer genes (BRCA1 and BRCA2).

10. Bodyweight

Postmenopausal women who are overweight or obese have a higher chance of getting breast cancer than those who are lean. The association between body mass index (or BMI, a measure of body fat) and breast cancer may be due to hormonal influence. Estrogen is secreted by fatty tissues in postmenopausal women. Obese pre-menopausal woman have a lower risk for the disease and this may be due to their anovulatory cycles.

11. Alcohol Consumption

Studies show a causal link between alcohol consumption and breast cancer. It has been suggested that alcohol consumers may have higher levels of sex hormones linked to the disease compared to those who do not consume alcohol.

12. Diet

Although there are many inconclusive studies linking diet with development of breast cancer, a large review of studies shows that a high total fat intake as well as high consumption of saturated fat is associated with increased breast cancer risk. On the other hand, high intake of phytoestrogens, particularly lignans, which are found in plants, is associated with a reduction of risk. Other foods that have been found to lower breast cancer risk are soy-based food products and high-fiber foods.

13. Shift Work

Working night shifts has been found to increase one’s risk for breast cancer. On the other hand, some studies have found that sleeping longer may reduce the risk for the disease. One explanation is that lower levels of a sleep hormone, melatonin, which has anti-cancer properties, may increase the likelihood for developing the cancer.

14. Smoking

Many studies link smoking as well as secondhand smoke with various types of cancers. Although some studies show that exposure to tobacco smoke may increase one’s risk for breast cancer, other studies show conflicting results.