Breast Cancer

Definition

Breast cancer is a malignant growth that begins in the tissues of the breast. Over the course of a lifetime, one in eight women will be diagnosed with breast cancer.

Alternative names

Cancer - breast

Causes, incidence, and risk factors

There are several different types of breast cancer. Ductal carcinoma begins in the cells lining the ducts that bring milk to the nipple and accounts for more than three-fourths of breast cancer.

Lobular carcinoma begins in the milk-secreting glands of the breast but is otherwise fairly similar in its behavior to ductal carcinoma. Other varieties of breast cancer can arise from the skin, fat, connective tissues, and other cells present in the breast.

Risk factors for breast cancer include:

Age and Gender: As with most cancers, age is a significant factor. In fact, 77% of new cases and 84% of breast cancer deaths occur in women aged 50 and older. More than 80% of breast cancer cases occur in women over 50. Less than 1% of breast cancers occur in men. The risk of breast cancer is clearly related to hormonal influences, but how these affect the disease and particularly types of the disease is not yet clear.
Genetic Factors and Family History of Breast Cancer: Some families appear to have a genetic tendency for breast cancer. Two variant genes have been found that appear to account for this: BRCA1 and BRCA2. The genes p53 and BARD1 also appear to be important. Researchers have identified some other defective genes that may cause breast cancer, including BRCA3 and Noey2 (which is a disease inherited only from the father's side of the family). These facts suggest that breast cancer is caused by the growth of genetically damaged cells. Such genetic damage is known to gradually accumulate in the cells of the body over time. Women carrying mutated BRCA1 and/or BRCA2 genes have a "head start" in this process. Hormonal influences are important because they encourage cell growth. High levels of hormones during a woman's reproductive years, especially when they are not interrupted by the hormonal changes of pregnancy, appear to increase the chances that genetically damaged cells will grow and cause cancer.
Early Menstruation and Late Menopause: Women who started menstrual periods early (before age 12) or went through menopause late (after age 55) are at higher risk. Also, women who have never had children or who had them only after the age of 30 have an increased risk.
Oral Contraceptives (birth control pills): Birth control pills may slightly increase the risk for breast cancer, depending on age, length of use, and other factors. No one knows how long the effects of the pill last after stopping it.
Hormone Replacement Therapy: Use of HRT for more than 5 years has been shown to slightly increase the risk of breast cancer and risk increases with longer use.
Physical Characteristics: Obesity is controversial as a risk factor. Some studies report obesity as a risk of breast cancer, possibly associated with higher levels of estrogen production in obese women.
Alcohol Consumption: Excessive alcohol use (more than 1-2 drinks a day) has been associated with an increased risk of breast cancer.
Chemicals: Some studies have pointed to exposure to estrogen-like chemicals that are found in pesticides and other industrial products as a possible increased risk of breast cancer.
DES: Women who took diethylstilbestrol (DES) to prevent miscarriage may have an increased risk of breast cancer.
Radiation: People exposed to radiation, particularly during childhood may face an increased risk for breast cancer in adulthood. Especially at risk are those that received chest irradiation for prior cancers.
Additional Risk Factors: Some studies show previous breast, uterine, ovarian, colon cancer, and a strong history of cancer in the family may increase the risk for breast cancer.

Prevention

Many risk factors cannot be controlled. Some experts in the field of diet and cancer agree that changes in diet and lifestyle may reduce the incidence of cancer generally.

Efforts have focused on early detection since breast cancer is more easily treated and often curable if it is found early. Breast self-examination (BSE), clinical breast examination (CBE) by a medical professional, and screening mammography are the three tools of early detection.

Most recommend breast self-examinations (BSE) once a month the week following your menstrual period if you are age 20 or older.

Regular clinical breast examinations (CBE) by a health professional are recommended for women between ages 20 and 39, at least every 3 years. After age 40, women should have a (CBE) by a health professional every year.

Mammography is the most effective way of detecting breast cancer early. Annual mammogram screenings are recommended for all women age 40 and older.

Two medicines are being studied currently that have been shown to reduce the risk of breast cancer: tamoxifen (Nolvadex ®) and raloxifene (Evista ®). Both are anti-estrogens in breast tissue.

Tamoxifen is already widely used to prevent recurrence in women who have been treated for breast cancer. For some women at very high risk of breast cancer, preventive use of these drugs may be appropriate. This should be discussed with a qualified physician.

Preventive Mastectomy, which is the surgical removal of one or both breasts, is an option to prevent breast cancer for women who are at very high risk for breast cancer.

Possible candidates for this procedure are women who have already had one breast removed due to cancer, women with a strong family history of breast cancer and those who have a mutation in genes p53, BRCA1, or have gene BRCA 2.

Symptoms

Breast lump or breast mass noted upon breast exam -- usually painless, firm to hard and usually with irregular borders
Lump or mass in the armpit
A change in the size or shape of the breast
Abnormal nipple discharge
- Usually bloody or clear-to-yellow or green fluid
- May look like pus (purulent)
Change in the color or feel of the skin of the breast, nipple, or areola
- Dimpled, puckered, or scaly
- Retraction, "orange peel" appearance
- Redness
- Accentuated veins on breast surface
Change in appearance or sensation of the nipple
- Pulled in (retraction), enlargement, or itching
Breast pain, enlargement, or discomfort on one side only
Any breast lump, pain, tenderness, or other change in a man
Symptoms of advanced disease are bone pain, weight loss, swelling of one arm, and skin ulceration

Signs and tests

Any worrisome breast changes should be confirmed and investigated by a medical professional. After getting as much information as possible about the symptom and any risk factors, the physician performs a physical examination including both breasts, armpits, and the area of the neck and chest. Additional tests and treatment may then be recommended:

X-ray mammography may help identify the breast mass.
Ultrasound (sonogram) can show whether the lump is solid or fluid-filled.
Needle aspiration or needle biopsy of breast lumps can demonstrate if they are fluid-filled and provide material to send to the laboratory for analysis. In the case of very small abnormalities visible only on mammography, special techniques are necessary.
A surgical biopsy or breast lump removal provides a portion or all of a breast lump for laboratory study.

If breast cancer is diagnosed, additional testing is performed, including chest X-ray and blood tests. Surgery, radiation, chemotherapy, or a combination of these may then be recommended, not only for treatment, but also to help determine the stage of disease. Staging is important to help guide future treatment and follow-up, and to give some idea of what to expect in the future.