Breast cancer is cancer arising in breast tissue. Cancer is simply a group of abnormal cells that have abnormal growth patterns.

• Although breast cancer is primarily a disease of women, about 1% of breast cancers occur in men.
• Breast cancer is the most common type of cancer in women and is the second leading cause of death by cancer in women, following only lung cancer.
• In 2000, the American Cancer Society estimated that 184,200 new cases of breast cancer were diagnosed in the United States.

• The breast has several lobes, which are divided into lobules and end in the milk glands. Tiny ducts run from the many tiny glands, connect together, and end in the nipple.
• These ducts are where 80% of breast cancers occur. This condition is called infiltrating ductal cancer.
• Cancer developing in the lobules is termed infiltrating lobular cancer. About 10-15% of breast cancers are of this type.
• Another type of breast cancer is inflammatory breast cancer.

• In situ is Latin for “in place” or “in site” and means that the changes haven’t spread from where they started.
• When these in situ changes occur in the ducts, they are called ductal carcinoma in situ (DCIS).
• When they happen in the lobules, they are called lobular carcinoma in situ (LCIS).
• DCIS is frequently diagnosed on routine mammography.

• Metastasis means that the cancer has spread from the place where it started into other tissues.
• The most common place for breast cancer to metastasize is into the lymph nodes under the arm or above the collarbone on the same side as the cancer.
• Other common sites of breast cancer metastasis are the brain, the bones, and the liver.

About 50% of women who develop breast cancer have no risk factors other than age and sex.

• Sex is the biggest risk because breast cancer occurs mostly in women.
• Age is another critical factor. Breast cancer may occur at any age, though the risk of breast cancer increases with age.
• The average woman at age 30 years has 1 chance in 280 of developing breast cancer in the next 10 years. This chance increases to 1 in 70 for a woman aged 40 years, and to 1 in 40 at age 50 years. A 60-year-old woman has a 1 in 30 chance of developing breast cancer in the next 10 years.

Family history has long been known to be a risk factor for breast cancer. The risk is highest if the affected relative developed breast cancer at a young age or if she is a close relative such as a mother, sister, daughter, or aunt.

• BRCA1 is an abnormal gene that, when inherited, markedly increases the risk of breast cancer to a lifetime risk of almost 85%. Women with this abnormal gene also have an increased likelihood of developing ovarian cancer. Women who have the BRCA1 gene tend to develop breast cancer at an early age.
• A second abnormal gene, BRCA2, increases the risk of developing breast cancer but not ovarian cancer.
• Testing for these genes is expensive and frequently not covered by insurance. In addition, women who test positive may have trouble getting or keeping health insurance.
• The issues around testing are complicated, and women who are interested in testing should discuss this with their health care providers

Hormonal influences play a role in the development of breast cancer.

• Women who start their periods at an early age or experience a late menopause have a higher risk of developing breast cancer.
• Conversely, being older at your first menstrual period and early menopause tend to protect one from breast cancer.
• Having a child before age 30 years may provide some protection, and having no children may increase your risk for developing breast cancer.
• Oral contraceptives have not been shown to increase or decrease a woman's the lifetime risk of breast cancer.
• A large study conducted by the Women's Health Initiative showed an increased risk of breast cancer in postmenopausal women who were on a combination of estrogen and progesterone for several years. Therefore, women who are considering hormone therapy for menopausal symptoms need to discuss the risk versus the benefit with their health care providers.

Breast cancer seems to occur more frequently in countries with high dietary intake of fat.

• This link is thought to be an environmental influence rather than genetic. For example, Japanese women, at low risk for breast cancer while in Japan, increase their risk of developing breast cancer after coming to the United States.
• Several studies comparing groups of women with high- and low-fat diets, however, have failed to show a difference in breast cancer rates.

Fibrocystic breast changes are very common.

• Fibrocystic breasts are lumpy with some thickened tissue and are frequently associated with breast discomfort, especially right before your menstrual period.
• This condition does not lead to breast cancer.
• However, certain types of benign breast changes, such as those diagnosed on biopsy as proliferative or hyperplastic, do predispose women to the later development of breast cancer.

• Radiation treatment seems to increase the likelihood of developing breast cancer but only after a long delay. For example, women who received radiation therapy to the upper body for treatment of Hodgkin disease before age 15 years have a significantly higher rate of breast cancer than the general population.

Early breast cancer has no symptoms. It is not painful.

Most breast cancer is discovered before symptoms are present, either by finding an abnormality on mammography or feeling a breast lump. You may also notice a lump under your arm or above your collarbone that does not go away. Other possible symptoms are breast discharge, nipple inversion, or changes in the skin overlying the breast.

• Most breast lumps are not cancerous. All breast lumps, however, need to be evaluated by a doctor.
• Breast discharge is a common problem and is rarely a symptom of cancer. Discharge is most concerning if it is from only 1 breast or if it is bloody. In any case, all breast discharge should be evaluated.
• Nipple inversion is a common variant of normal nipples, but nipple inversion that is a new development can be of concern.
• Changes in the skin of the breast include redness, changes in texture, and puckering. These changes are usually caused by skin diseases but occasionally can be associated with breast cancer.

Until the late stages of breast cancer, when care is confined to easing suffering and increasing comfort, home care for breast cancer is not appropriate. All women with breast lumps should be seen by a doctor, and breast cancer should be treated by cancer specialists (oncologists).

In this disease, patient preference plays a major role in decisions regarding treatment. Treatment depends on a large number of factors, including the type of breast cancer, the hormone receptor status of the tumor, the stage of the tumor, the size of the breast, and the person's general health, age, and menstrual status (has or has not been through menopause).

• Radiation is a local treatment and therefore works only on tumor cells that are directly in its beam.
• Radiation is used most often in people who have undergone conservative surgery such as lumpectomy. Conservative surgery is designed to leave as much of the breast tissue in place as possible.
• Radiation therapy is usually given 5 days a week over 5-6 weeks. Each treatment takes only a few minutes.
• Radiation therapy is painless and has relatively few side effects. However, it can irritate the skin or cause a burn similar to a bad sunburn in the area.

Chemotherapy consists of the administration of medications that kill cancer cells or stop them from growing.

• Most chemotherapy agents are given through an IV line, but some are given as pills.
• Chemotherapy is usually given in "cycles." Each cycle includes a period of intensive treatment lasting a few days or weeks followed by a few weeks of recovery. Most people with breast cancer receive at least 2, more often 4, cycles of chemotherapy to begin with. Tests are then repeated to see what effect the therapy has had on the cancer.
• Chemotherapy differs from radiation in that it treats the entire body and thus may find stray tumor cells that may have migrated from the breast area.
• The side effects of chemotherapy are well known. Side effects depend on which drugs are used, but some that are common to many of these drugs include loss of hair, nausea and vomiting, loss of appetite, fatigue, and low blood cell counts, which may cause you to be more susceptible to infections, to feel sick and tired, or to bleed more easily than usual.

• Adjuvant chemotherapy is given to people who have had curative treatment for their breast cancer, such as surgery and radiation. It is given to decrease the possibility of the disease returning.
• Presurgical chemotherapy is given to shrink a large tumor and/or to kill stray cancers cells. This increases the chance that surgery will get rid of the cancer completely.
• Regular chemotherapy is routinely administered to people with breast cancer that has spread beyond the confines of the breast or local area.

• In some cases, it is beneficial to suppress a woman's natural hormones with drugs; in others, it is beneficial to add hormones.
• At present, tamoxifen (Nolvadex) is the most commonly prescribed hormone treatment. It is used both for breast cancer prevention and for treatment. In the very elderly, tamoxifen alone has minimal side effects and may dramatically improve advanced breast cancer.
• Another agent, fulvestrant (Faslodex) has recently been approved in the United States. It is indicated for the treatment of hormone receptor–positive metastatic breast cancer in postmenopausal women with disease progression following antiestrogen therapy (for example, treatment with tamoxifen).

• Monoclonal antibody therapy for breast cancer is currently being investigated.
• Trastuzumab (Herceptin) is an antibody against the HER-2 protein, a protein responsible for cancer cell growth in many women with breast cancer (about 30% of breast cancers).
• It is under active study in women whose tumors have certain characteristics that suggest they may respond.

Surgery is the mainstay of therapy for breast cancer. The choice as to which type of surgery is based on a number of factors, including the size and location of the tumor, the type of tumor, and the person's overall health and personal wishes. Breast-sparing surgery is often possible.

• Lumpectomy involves removal of the cancerous tissue and a surrounding area of normal tissue. Generally the lymph nodes in the armpit are sampled at the same time. This is not considered curative and should almost always be done in association with other therapy such as radiation therapy with or without chemotherapy or hormonal therapy.
• Simple mastectomy removes the entire breast but no other structures. If the cancer is invasive, this surgery alone will not cure it. It is a common treatment for DCIS, a noninvasive type of breast cancer.
• Modified radical mastectomy removes the breast and the axillary (underarm) lymph nodes but does not remove the underlying muscle of the chest wall. Although additional chemotherapy or hormonal therapy is almost always offered, surgery alone is considered adequate to control the disease if it has not metastasized.
• Radical mastectomy involves removal of the breast and the underlying chest wall muscles, as well as the underarm contents. This surgery is no longer done because current therapies are less disfiguring and have fewer complications.