The American Cancer Society defines a risk factor as anything that increases a person's chance of getting a disease. Having a risk factor--or several risk factors for that matter--doesn't ensure a person will develop that disease. The risk factors for each disease vary. Some are controllable, while others are not.
Using Oral Contraceptives
As the American Cancer Society explains, women who use oral contraceptives have a slightly higher risk of developing breast cancer than women who have not used them at all. This risk declines the longer a woman goes without use though, and once 10 years pass, a woman's risk of developing breast cancer from the use of birth control pills is non-existent.
When a Woman Has Children
Women who never have children, or who give birth after the age of 30, according to the American Cancer Society, also have a slightly higher risk than women who have children at a younger age. The more pregnancies a woman experiences, the fewer menstrual cycles she experiences. This reduces the amount of estrogen she is exposed to, and this female hormone can contribute to the growth of cancer cells.
Choosing to Bottle Instead of Breast-Feed
Breast-feeding appears to lower a woman's risk of developing breast cancer when she continues doing so for a period of 1 1/2 to 2 years, according to the American Cancer Society. In many cases, breast-feeding reduces the number of menstrual cycles a woman has, which again reduces her overall exposure to estrogen.
Being Overweight
This risk factor is one that is complex, as it has many facets. Prior to menopause, a woman's ovaries produce a majority of her estrogen. After menopause, when the ovaries no longer produce this hormone, the fat tissue in the body begins making a majority of her estrogen. The more fat a woman has, the more estrogen she produces.
Women who gain weight as adults appear to be at greater risk for developing breast cancer than those who have been overweight since childhood, explains the American Cancer Society.
Hormone Replacement Therapy
Also known as post-menopausal therapy, doctors have been prescribing this for years to help relieve the symptoms of menopause and to help prevent the onset of osteoporosis. The American Cancer Society explains that two types exist--one with estrogen alone for women who no longer have a uterus and a progesterone/estrogen combination for women with a uterus. In as few as two years, the combination therapy increases both the risk of developing and dying from breast cancer. The Society further explains that women taking estrogen for a short period of time did not face an increased risk of developing breast cancer, however when taken for more than 10 years, the risk of developing both breast and ovarian cancer rose.
