Breast cancer is a type of cancer where abnormal cells in the breast divide and grow. As the Susan G. Komen site explains, tumors tend to grow slowly--in some cases, as long as 10 years before diagnosis. Changes in DNA in single breast cells appear to be a more likely cause of breast cancer than inherited causes, according to the American Cancer Society (ACS). The cause of most of these changes is unknown. However, certain risk factors are linked to the disease.
Gender
Being a female is the greatest risk factor for developing breast cancer. While men can develop this disease, both the ACS and Susan G. Komen state that it is 100 times more common in women.
Age
The Susan G. Komen site refers to age as a "well established risk factor for breast cancer." Although women under the age of 40 have a low breast cancer rate, these rates increase with age and are highest in women over the age of 70. Ninety-five percent of women diagnosed with breast cancer are age 40 or older.
Family History
A woman's risk for developing breast cancer doubles when she has close blood relatives--such as a grandmother, mother, aunt or sister--with breast cancer. Women with other blood relatives with breast cancer, whether it be on their father or mother's side, also faces a higher risk for this disease, according to the ACS. Although these factors should not be ignored, approximately 70 to 80 percent of women with breast cancer have no family history.
Personal History
A difference exists between recurrent tumors and second primary breast cancer. For breast cancer survivors, a recurrent tumor is the return of the original cancer, while secondary primary breast cancer is a new cancer completely unrelated to the first. It can present itself in either breast, but if it develops in the breast where the first cancer was found, it generally appears in another area. Women who have a personal history of breast cancer have a greater risk of experiencing second primary breast cancer than women who have never had breast cancer at all.
Ethnicity
While Caucasian women face a slightly greater risk than African American women of developing breast cancer, according to the ACS, African American women are more likely to lose their lives to this disease. Tumors in African American women grow faster, although the cause is not known.
Lifestyle
Some risk factors of breast cancer are within a woman's control and may reduce the risk of developing this disease.
Obesity is one of these factors, and according to the ACS, women who are overweight face a greater risk of developing breast cancer, especially if the weight gain took place during adulthood or after menopause.
Another is choosing not to breast-feed. Women who breast-feed reduce their number of periods, thus reducing their estrogen levels. This decreases their risk of developing breast cancer slightly, especially if the breast-feeding took place for 1 1/2 to 2 years.
