CANCER RISK FACTORS: HORMONAL RISK FACTORS
Hormones influence a cell's growth and development, so if there is an excess or deficit of hormones in the body, then cells will not function properly and may grow abnormally or aberrantly and become cancer cells.
Women who have never been pregnant have a higher risk of developing breast cancer than women who do have children; and women who become pregnant before age 20 have a reduced risk. Women whose mothers or other close relatives have breast cancer have three times the normal risk of getting breast cancer. Women who do not menstruate during their lifetime have a three to four times higher risk of developing breast cancer after the age of 55. A lower risk of breast cancer is seen in women whose ovaries cease to function or are removed surgically before age 35.
There has been considerable controversy over whether oral contraceptives can cause breast and liver cancer. Many studies seem to indicate that hormones used in birth control pills are a risk factor for breast or liver cancer.35,36 Estrogens in these oral contraceptives can cause benign liver growths as well, which can bleed extensively and cause problems related to bleeding.
Daughters of women who received DES (diethylstilbestrol) therapy during pregnancy have developed cancer of the cervix and vagina. Sons of women who took DES have a higher risk of developing cancer of the testicles because DES causes urinary tract abnormalities including undescended testicles, which, if not corrected surgically before age 6, can develop into cancer of the testicles. Furthermore, women exposed to these same synthetic estrogens in adult life have a higher risk of developing cancer of the cells that line the inside of the uterus (endometrial cancer). Male hormones can predispose to both benign and malignant liver tumors.
Obesity is directly correlated with breast cancer and endometrial cancer. Fibrocystic breast disease, a benign disease that affects 50 percent of all women sometime during their lives, probably represents a hormone imbalance. If a woman has had the disease over many years, she is at an increased risk of developing breast cancer.