As of 2010, the second leading cause of cancer deaths among women is breast cancer, according to Imaginis, an award-winning, physician-edited information source for women's health topics. Changes in a person's DNA can result in normal breast cells becoming cancerous, reports the American Cancer Society (ACS). Although no specific cause has been identified, a number of risk factors have.
Gender
The greatest risk factor for developing breast cancer is gender. Although breast cancer can occur in both men and women, it is 100 times more common in women than in men, according to ACS.
Family History
Women whose close blood relatives--on the mother or father's side--face a greater risk of developing breast cancer. ACS explains that this risk doubles for women whose mother, sister or daughter suffers from the disease.
Personal History
ACS explains that women with a history of breast cancer have a greater risk of developing cancer in the other breast or in a different area of the same breast the original cancer first appeared.
Genetics
Between 5 and 10 percent of breast cancers may have a genetic link, according to the Mayo Clinic. This is due to a change in genes, which are being passed down through generations. Although a number of genes could cause breast cancer, two specific types increase the likelihood--BRCA1 and BRCA2. ACS explains that women with these genes have an 80-percent chance of developing both breast and ovarian cancer in their lifetimes.
Age
As a woman becomes older, her risk of developing breast cancer increases, according to ACS. Approximately two out of three women with invasive breast cancer are age 55 or older when the doctor detects the cancer.
