Breast cancer affects nearly 195,000 people and claims the lives of over 40,000 people each year in the United States. While many of the risk factors for breast cancer cannot be changed, understanding the lifestyle risk factors associated with the disease can help people make better health choices. These decisions can reduce the risk for developing breast cancer and other life-threatening diseases.
Age and Gender
According to physicians from the Mayo Clinic, women who are over the age of 60 have a greater risk for breast cancer than younger women. Being female is also a risk factor for breast cancer, as this type of cancer occurs more frequently in women. The American Cancer Society indicates that breast cancer is 100 times more common in women than in men.
High Number of Menstrual Cycles
Women who have a higher number of menstrual cycles than others are at a greater risk for developing breast cancer. This can occur due to early menstruation or late menopause. Early menstruation is defined by the Mayo Clinic as having the first menstrual period before the age of 12. The American Cancer Society defines late menopause as menopause that occurs after a woman is 55 years of age. Having more menstrual cycles increases the amount of estrogen and progesterone a woman is exposed to, which can increase the risk for breast cancer.
Radiation Exposure
Women who received radiation therapy to the chest as children or adolescents are at an increased risk of breast cancer. According to the American Cancer Society, the risk appears to be highest for women who received radiation therapy while their breast tissues were still developing. Radiation therapy can be used to treat diseases such as Hodgkin disease and non-Hodgkin lymphoma.
Obesity
Obesity can increase the risk for breast cancer because fatty tissues can produce estrogen. After menopause, a woman's estrogen comes mostly from fatty tissue. When more fatty tissue is present, estrogen levels increase. Since estrogen can contribute to the development of breast cancer, this increases a woman's risk for developing the disease. Researchers from the American Cancer Society believe that fat around the waist poses a higher risk than fat from other areas of the body. However, further research is needed to determine how fat around the waist could increase the risk of breast cancer.
Gene Mutations
Genetic mutations are responsible for approximately five to ten percent of breast cancer cases, according to the American Cancer Society. The BRCA1 and BRCA2 genes work to prevent cancer by manufacturing proteins that keep cells from growing abnormally. When one of these genes is mutated, the risk of developing breast cancer can be as high as 80 percent. Other genetic mutations have also been linked to breast cancer. Families with a high rate of cancer occurrence have been found to have mutations of the ATM gene, which helps to repair damaged DNA. Mutations of the CHEK2 gene cause the risk of developing breast cancer to double. PTEN is a gene that regulates cell growth. When the gene is mutated, it increases the risk for malignant and benign breast tumors and growths in the reproductive system and digestive tract.
Benign Breast Conditions
Medical conditions that affect the breasts can increase the risk of developing breast cancer. Benign conditions are classified into three groups, with each group representing a higher risk of breast cancer. Non-proliferative lesions affect breast cancer risk minimally. These conditions include adenosis, hyperplasia, fibrocystic disease, simple fibroadenoma, fat necrosis, duct ectasia, mastitits and other benign tumors. Proliferative lesions without atypia involve excessive growth of cells within the lobules or ducts of the breast tissue. According to the American Cancer Society, these benign breast lesions increase a woman's risk of developing breast cancer by one and a half to two times. These lesions include complex fibroadenoma, sclerosing adenosis, radial scar, several papillomas and usual ductal hyperplasia. Proliferative lesions with atypia involve excessive growth of cells within the lobules and ducts of the breast tissue. These cells appear abnormal and can increase a woman's risk of developing breast cancer by four to five times. The conditions include atypical lobular hyperplasia and atypical ductal hyperplasia.
History of Breast Cancer
Personal history of breast cancer and a family history of breast cancer can increase a woman's risk of developing the conditions. Statistics from the American Cancer Society indicate that having one first-degree relative with the disease doubles the risk of developing cancer of the breast. Having two first-degree relatives that have the disease increases a woman's risk of developing breast cancer by five times. Someone who has had cancer in one breast is at an increased risk for developing a new cancer in another part of the same breast or in the other breast. The risk is increased three to four times if someone has already had breast cancer.
Hormone Replacement Therapy
Hormone replacement therapy is sometimes used in menopausal women who are at risk for developing osteoporosis. Hormone replacement therapy can also be used to treat vaginal and vulvar atrophy caused by menopause. Combined hormone replacement therapy, which includes estrogen and progesterone, has been found to increase the risk of developing breast cancer. It also seems to increase the risk of dying from breast cancer. Hormone replacement therapy that uses only estrogen does not appear to substantially increase the risk of developing breast cancer. However, using estrogen replacement therapy for more than ten years has been found to increase the risk of developing breast cancer.
