Breast cancer is a cancer that starts in the breast, usually in the inner lining of the milk ducts or lobules. There are different types of breast cancer, with different stages (spread), aggressiveness, and genetic makeup. With best treatment, 10-year disease-free survival varies from 98% to 10%. Treatment includes surgery, drugs (hormone therapy and chemotherapy), and radiation.
There are two main types of breast cancer. Ductal carcinoma starts in the tubes (ducts) that move milk from the breast to the nipple. Most breast cancers are of this type. Lobular carcinoma starts in parts of the breast, called lobules, that produce milk.
In rare cases, breast cancer can start in other areas of the breast.
Many breast cancers are sensitive to the hormone estrogen. This means that estrogen causes the breast cancer tumor to grow. Such cancer is called estrogen receptor positive cancer or ER positive cancer.
Worldwide, breast cancer is the second most common type of cancer after lung cancer (10.4% of all cancer incidence, both sexes counted and the fifth most common cause of cancer death. In 2004, breast cancer caused 519,000 deaths worldwide (7% of cancer deaths; almost 1% of all deaths).
Breast cancer is about 100 times as frequent among women as among men, but survival rates are equal in both sexes.
CAUSES
The primary risk factors that have been identified are sex, age, childbearing, hormones, a high-fat diet, alcohol intake, obesity, and environmental factors such as tobacco use, radiation and shiftwork. However, studies of environmental and lifestyle factors only attribute a small increase in breast cancer to each factor. Furthermore, these studies are not randomized, controlled trials, and so they may associate breast cancer with factors that don't actually cause breast cancer.
- Personal history of breast cancer: A woman who had breast cancer in one breast has an increased risk of getting cancer in her other breast.
- Family history: A woman's risk of breast cancer is higher if her mother, sister, or daughter had breast cancer. The risk is higher if her family member got breast cancer before age 40. Having other relatives with breast cancer (in either her mother's or father's family) may also increase a woman's risk.
- Certain breast changes: Some women have cells in the breast that look abnormal under a microscope. Having certain types of abnormal cells (atypical hyperplasia and lobular carcinoma in situ [LCIS]) increases the risk of breast cancer.
- Race: Breast cancer is diagnosed more often in Caucasian women than Latina, Asian, or African American women.
- No physical activity: Women who are physically inactive throughout life may have an increased risk of breast cancer. Being active may help decrease risk.
- Tamoxifen may interact unfavorably with certain antidepressants when used for prevention of breast cancer recurrence.
- Abortion-breast cancer hypothesis: Mainstream organizations such as the American Cancer Society and National Cancer Institute have concluded there is no link between induced abortion and breast cancer, although a minority of doctors continue to disagree.
- Breast implants, using antiperspirants, and wearing underwire bras do not raise your risk for breast cancer. There is no evidence of a direct link between breast cancer and pesticides.
SYMPTOMS
Early breast cancer usually does not cause symptoms. This is why regular breast exams are important. As the cancer grows, symptoms may include:
- Breast lump or lump in the armpit that is hard, has uneven edges, and usually does not hurt
- Change in the size, shape, or feel of the breast or nipple -- for example, you may have redness, dimpling, or puckering that looks like the skin of an orange
- Fluid coming from the nipple -- may be bloody, clear-to-yellow, or green, and look like pus
Men get breast cancer, too. Symptoms include breast lump and breast pain and tenderness.
- Symptoms of advanced breast cancer may include:
- Bone pain
- Breast pain or discomfort
- Skin ulcers
- Swelling of one arm (next to breast with cancer)
- Weight loss
TREATMENT
The mainstay of breast cancer treatment is surgery. Adjuvant hormonal therapy (with tamoxifen or an aromatase inhibitor) is given when the tumor expresses estrogen receptors or progesterone receptors.
Chemotherapy is given for more advanced stages of disease. Monoclonal antibodies are sometimes used, especially for HER2-positive tumors. Radiotherapy is given after surgery to the region of the tumor bed, to destroy microscopic tumors that may have escaped surgery. Treatments are constantly being evaluated in randomized, controlled trials, to evaluate and compare individual drugs, combinations of drugs, and surgical and radiation techniques.
In planning treatment, doctors can also use PCR tests like Oncotype DX or microarray tests that predict breast cancer recurrence risk based on gene expression.
Radiation therapy is also used to help destroy cancer cells that may linger after surgery. Radiation can reduce the risk of recurrence by 50-66% (1/2 - 2/3rds reduction of risk) when delivered in the correct dose.
PREVENNTION
Regular exercise, weight loss, avoidance of alcohol, stressors, toxic chemicals and environmental pollutants are all helpful measures in the prevention of breast cancer. Dietary inclusion of dried beans, cruciferous vegetables, and whole grains have also proven beneficial. Brazil nuts, rich in the mineral selenium, when combined with natural vitamin E as found in almonds and walnuts are also highly effective in reducing cancer risk.
Breast cancer is more easily treated and often curable if it is found early.
Early detection involves:
- Breast self-exams (BSE)
- Clinical breast exams by a medical professional
- Screening mammography
Most experts recommend that women age 20 and older examine their breasts once a month during the week following the menstrual period.
Women between the ages 20 and 39 should have a doctor examine their breasts at least once every 3 years.
After age 40:
- Women 40 and older should have a mammogram every 1 - 2 years, depending on their risk factors. Women should call their doctor immediately if they notice in change in their breasts whether or not they do proutine breast self-exams.
- Women 40 and older should have a complete breast exam by a health care provider every year.
- Mammography is the most effective way of detecting breast cancer early.
