Understanding Breast Cancer -- the Basics
What Is Breast Cancer? continued...
If eight women were to live to be at least 85, one of them would be expected to develop the disease at some point during her life. Two-thirds of women with breast cancer are over 50, and most of the rest are between 39 and 49.
Fortunately, breast cancer is very treatable if detected early. Localized tumors can usually be treated successfully before the cancer spreads; and in nine out of 10 cases, the woman will live at least another five years. However, late recurrences of breast cancer are common.
Once the cancer begins to spread, treatment becomes difficult, although treatment can often control the disease for years. Improved screening procedures and treatment options mean that at least seven out of 10 women with breast cancer will survive more than five years after initial diagnosis and half will survive more than 10 years.
What Causes Breast Cancer?
Although the precise causes of breast cancer are unclear, we know what the main risk factors are. Still, most women considered at high risk for breast cancer do not get it. On the other hand, 75% of women who develop breast cancer have no known risk factors. Among the most significant factors are advancing age and family history. Risk increases slightly for a woman who has certain benign breast lumps and increases significantly for a woman who has previously had breast cancer or endometrial, ovarian, or colon cancer.
A woman whose mother, sister, or daughter has had breast cancer is two to three times more likely to develop the disease, particularly if more than one first-degree relative has been affected. This is especially true if the cancer developed in the woman while she was premenopausal, or if the cancer developed in both breasts. Researchers have now identified two genes responsible for some instances of familial breast cancer -- BRCA1 and BRCA2. About one woman in 200 carries one of these genes. Having a BRCA 1 or BRCA 2 gene predisposes a woman to breast cancer and -- while it does not ensure that she will get breast cancer -- her lifetime risk is 56%-85%. These genes also predispose to ovarian cancer and are associated with pancreas cancer, melanoma, and male breast cancer (BRCA2).