What Are the Risk Factors for Breast Cancer

What Are the Risk Factors for Breast Cancer

What Are the Risk Factors for Breast Cancer?

• Age and gender. The majority of breast cancer patients are women. The risk of breast cancer starts around age 40 and peaks at age 70. Men and younger women can also be afflicted with breast cancer, albeit at a lower incidence rate.

• Alcohol. Consumption of alcoholic beverages at two to three drinks per day increases the risk of breast cancer by 20%. Alcohol raises the blood level of estrogen, a female hormone that stimulates the growth and proliferation of cancer cells in the breast and increases the risk of breast cancer in postmenopausal women. Alcohol also lowers the blood level of folic acid, an essential nutrient that supports the synthesis and repair of DNA. The lack of folic acid increases errors in the synthesis of new DNA and destabilizes the structure of DNA, leading to gene mutation and tumor transformation.

• Family and genetics. Several gene polymorphic variants—such as BRCA1, BRCA2, p53, and PALB2—are associated with breast cancer. Among them, BRCA1 and BRCA2 are well-known genetic risk factors for breast cancer. About 8–10% of Ashkenazi Jews are carriers of the BRCA1 gene, while about 1% of Asians or Africans carry either the BRCA1 or BRCA2 gene.

• Menstruation. Women who began menstruation at age 12 or younger have a 20% increased risk of breast cancer. High blood levels of estrogen stimulate the growth and proliferation of cancerous cells in the breast.

• Contraceptives. The use of oral contraceptives increases the risk of breast cancer by 20–30%. The association between the risk of breast cancer and other birth control devices, such as the IUD or birth control patches, is not as clear. However, all contraceptive medications alter the blood levels of female sex hormones, and they will inevitably affect women's health. In addition, women who receive estrogen replacement therapy for more than two years have an increased risk of breast cancer.

• Smoking. Lipophilic carcinogens, such as nitrosamines and aromatic amines in cigarette smoke, can enter the bloodstream and travel to fat tissues in the breast. These toxic chemicals can cause gene mutations and the transformation of breast cells to malignant cells. The p53 gene encodes a protein that supports the cell cycle and acts as a tumor suppressor. Women smokers were found to have more p53 mutated genes compared to nonsmoking women. Mutations in the p53 gene lead to unabated cell growth and increase the incidence rate of breast cancer.

• Overweight/obesity. Premenopausal women who are overweight experience a 20–40% decreased risk of breast cancer. However, postmenopausal women who are overweight experience a 30–60% increased risk of breast cancer. Obesity is a chronic inflammatory condition that stimulates the production of insulin and insulin-like growth factor and promotes the growth and proliferation of cancerous cells in the breast, particularly in postmenopausal women.

• Lack of exercise. Regular exercise decreases the risk of breast cancer by 10–20%. Exercise controls body weight, increases insulin sensitivity, and lowers estrogen levels, thus reducing the risk of breast cancer, particularly in postmenopausal women. On the other hand, a lack of exercise elevates the blood level of insulin and causes insulin resistance. Insulin resistance is associated with the growth and proliferation of cancer cells in the breast.

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