American Medical Association Family Medical Guide - American Medical Association [576]
Breast Cancer
Cancer of the breast is the most common cancer in women (although lung cancer kills more women each year). The risk of developing breast cancer is actually much lower than that of several other life-threatening diseases, including heart disease (the No. 1 killer of American women), stroke, type 2 diabetes, and osteoporosis. When breast cancer is detected at an early stage and treated, it is cured in 9 out of 10 cases.
Risk Factors
Breast cancer results from changes in the genes of breast cells. The precise cause of these genetic mutations is not fully understood. Breast cancer develops more frequently in whites than in blacks or Asians. The following factors increase a woman’s risk of developing breast cancer:
• Age Age is the most significant risk factor for breast cancer. Breast cancer is uncommon in women younger than 35; the risk is higher in women over 50 and especially high in women over 60. Your risk of developing breast cancer at 60 is about 26 times greater than it is at 35.
• Health history If you have breast cancer in one breast, you are at increased risk of developing a cancer in your other breast.
• Family history Although the vast majority of cases of breast cancer occur in women who have no family history of the disease, heredity can play a role. Women who have a close relative (mother, sister, or daughter) with breast cancer (especially if it develops at a young age) are at increased risk of also developing the cancer.
• Genetic changes Alterations in some genes (such as BRCA1 and BRCA2) increase a woman’s risk of developing breast cancer. Five to 10 percent of cases occur in women who inherit one of these genes. If several members of your family have had breast cancer, your doctor may talk to you about genetic testing (see page 953) to determine if you have a genetic mutation in one of these genes. You may be able to delay or prevent the cancer or at least have it diagnosed at an early stage.
• Estrogen Exposure to the female hormone estrogen (either made by the body or taken as a drug) appears to play a role in a woman’s risk of breast cancer. For example, breast cancer is slightly more common in women who start menstruating early (before age 12) or who go through menopause late (after age 55). Women who have never had a baby or breastfed (and therefore have never had a break in their menstrual cycle) also appear to have a slightly higher risk of breast cancer than women who have had a baby.
• Late childbearing Women who have their first child after age 30 are at greater risk of developing breast cancer than women who have babies at younger ages. The reason for this is not clear, but doctors think it may be that early pregnancy causes breast cells to mature, which makes them less likely to undergo changes that could lead to cancer.
• Radiation therapy Women whose breasts have been exposed to radiation during radiation therapy, such as for Hodgkin’s disease (see page 626), are at increased risk of developing breast cancer. The younger the woman when she has the therapy, the higher her risk.
Finding Cancer Early
Because there is no known way to prevent breast cancer, the best chance for successful treatment is to detect it at an early stage. Performing a breast self-examination (see page 138) every month will help you detect a lump early. Have a mammogram (see page 141) as frequently as your doctor recommends, usually starting at about age 40. When a tumor is detected at an early stage and treated before it has spread, you can expect a complete cure or many years of good health.
Symptoms
If you have breast cancer, you may feel a lump or thickening in or near your breast or in the underarm area during a breast self-examination. The lump may or may not be painful; breast pain is usually a sign of a noncancerous condition, although there are exceptions. Although most breast lumps turn out to be benign, see your doctor if you find a lump or notice any of the following:
• A change in the size or shape of a breast
• Spontaneous nipple discharge (especially