Cells in the body normally divide (reproduce) only when new cells are needed. Sometimes, cells in a part of the body grow and divide out of control, which creates a mass of tissue called a tumor. If the cells that are growing out of control are normal cells, the tumor is called benign (not cancerous.) If however, the cells that are growing out of control are abnormal and don't function like the body's normal cells, the tumor is called malignant (cancerous).

Cancers are named after the part of the body from which they originate. Breast cancer originates in the breast tissue. Like other cancers, breast cancer can invade and grow into the tissue surrounding the breast. It can also travel to other parts of the body and form new tumors, a process called metastasis.

We do not know what causes breast cancer, although we do know that certain risk factors may put you at higher risk of developing it. A risk factor is anything that puts you at higher risk of developing a particular disease. A person's age, genetic factors, personal health history and diet all contribute to breast cancer risk.

Breast cancer is the most common cancer among women other than skin cancer.

Breast cancer is the second-leading cause of cancer death in women after lung cancer -- and is the leading cause of cancer death among women ages 35 to 54. In 2001, 192,200 women will be diagnosed with breast cancer and approximately 40,600 will die. Although these numbers may sound frightening, research reveals that the mortality rate could decrease by 30% if all women age 50 and older who need a mammogram had one.

Only 5-10% of breast cancers occur in women with a clearly defined genetic predisposition for the disease. The majority of breast cancer cases are "sporadic," meaning there is no direct family history of the disease. The risk for developing breast cancer increases as a woman ages.

What Are The Warning Signs Of Breast Cancer?

• Lump or thickening in or near the breast or in the underarm that persists through the menstrual cycle
• A mass or lump, which may feel as small as a pea
• A change in the size, shape or contour of the breast
• A blood-stained or clear fluid discharge from the nipple
• A change in the feel or appearance of the skin on the breast or nipple (dimpled, puckered, scaly or inflamed)
• Redness of the skin on the breast or nipple
• An area which is distinctly different from any other area on either breast
• A marble-like hardened area under the skin

These changes may be found when performing monthly breast self-exams. By performing breast self-exams, you can become familiar with the normal monthly changes in your breasts.

Breast self-examination should be performed at the same time each month, three to five days after your menstrual period ends. If you have stopped menstruating, perform the exam on the same day of each month.

The most common types of breast cancer are:

• Infiltrating (invasive) ductal carcinoma. This cancer starts in the milk ducts of the breast. Then it breaks through the wall of the duct and invades the fatty tissue of the breast. This is the most common form of breast cancer, accounting for 80% of cases.
• Ductal carcinoma in situ is ductal carcinoma in its earliest stage (stage 0). In situ refers to the fact that the cancer hasn't spread beyond its point of origin. In this case, the disease is confined to the milk ducts and has not invaded nearby breast tissue. If untreated, ductal carcinoma in situ may become invasive cancer. It is almost always curable.
• Infiltrating (invasive) lobular carcinoma. This cancer begins in the lobules of the breast where breast milk is produced, but has spread to surrounding tissues or the rest of the body. It accounts for 10-15% of breast cancers.
• Lobular carcinoma in situ is cancer that is only in the lobules of the breast. It isn't a true cancer, but serves as a marker for the increased risk of developing breast cancer later, possibly in both breasts. Thus, it is important for women with lobular carcinoma in situ to have regular clinical breast exams and mammograms.

Cancers can also form in other parts of the breast but are more rare.

Early stage or stage 0 breast cancer is when the disease is localized to the breast and lymph nodes (carcinoma in situ).

Stage I breast cancer: The cancer is smaller than 1 inch across and it hasn't spread anywhere.

Stage II breast cancer is one of the following: the tumor is less than an inch across but has spread to the underarm lymph nodes (IIA); or the tumor is between 1-2 inches (with or without spread to the lymph nodes); or the tumor is larger than 2 inches and not has spread to the lymph nodes under the arm (both IIB).

Advanced breast cancer (metastatic) results after cancer cells spread to the lymph nodes and to other parts of the body.

Stage III breast cancer is also called locally advanced breast cancer. The tumor is larger than 2 inches and has spread to the lymph nodes under the arm, or a tumor that is any size with cancerous lymph nodes that adhere to one another or surrounding tissue (IIIA).

Stage IIIB breast cancer is a tumor of any size that has spread to the skin, chest wall or internal mammary lymph nodes (located beneath the breast and inside the chest).

Stage IV breast cancer is defined as a tumor, regardless of size, that has spread to places far away from the breast, such as bones, lungs or lymph nodes.

During your regular physical examination your doctor will take a careful personal and family history and performing a breast examination and possibly one or more other tests.

Breast Examination: During the breast exam, the doctor will carefully feel the lump and the tissue around it. Breast cancer usually feels different (in size, texture and if it moves easily) than benign lumps.

Mammography: an X-ray test of the breast can give important information about a breast lump.

Digital mammography: A new technique in which an X-ray image of the breast is recorded into a computer rather than on a film. In January 2000, the FDA approved a digital mammography system that may offer potential advantages over the use of standard X-ray film. Study results have not shown that digital images are more effective in finding cancer than X-ray film images, but they may reduce your exposure to radiation.

Ultrasonography: This test uses sound waves to detect the character of a breast lump -- whether it is a fluid filled cyst (not cancerous) or a solid mass (which may or may not be cancer). This may be performed along with the mammogram.

Based on the results of these tests, your doctor may or may not request a biopsy test to get a sample of the breast mass cells or tissue. Biopsies are performed using surgery or needles.

After the sample is removed, it is sent to a lab for testing. A pathologist -- a doctor who specializes in diagnosing abnormal tissue changes -- views the sample under a microscope and looks for abnormal cell shapes or growth patterns. When cancer is present, the pathologist can tell what kind of cancer it is (ductal or lobular carcinoma) and whether it has spread beyond the ducts or lobules (invasive).

Laboratory tests, such as hormone receptor tests (estrogen and progesterone) can show whether the hormones help the cancer to grow. If the test results show that hormones help the cancer grow (a positive test), the cancer is likely to respond to hormonal treatment. This therapy deprives the cancer of the estrogen hormone.

Breast cancer diagnosis and treatment are best accomplished by a team of experts working together with the patient. Each patient needs to evaluate the advantages and limitations of each type of treatment, and work with her team of physicians to develop the best approach.

Other Diagnostic Tests

Other methods being investigated but not yet available include:

• Scintimammography: A technique in which radioactive contrast agents are injected into a vein in the arm. An image of the breast is taken with a special camera, which detects the radiation (gamma rays) emitted by the dye. Tumor cells, which contain more blood vessels than benign tissue, collect more of the dye and project a brighter image.
• Positron Emission Tomography (PET) scanning: A technique that measures a signal from injected radioactive tracers that migrate to the rapidly dividing cells of cancer. The PET scanner picks up the signal and creates an image.
• Magnetic Resonance Imaging (MRI): A test that produces very clear pictures, or images, of the human body without the use of X-rays. MRI uses a large magnet, radio waves and a computer to produce these images.
• Scientists are also exploring ways to detect breast cancer or markers of cancer in the blood, urine and in fluid taken from the nipple.

Follow these three steps for early detection:

1. Get a mammogram. The American Cancer Society recommends having a baseline mammogram at age 35, and a screening mammogram every year after age 40. Mammograms are an important part of your health history. If you go to another healthcare provider, or move, take the film (mammogram) with you.

2. Examine your breasts each month after age 20. You will become familiar with the contours and feel of your breasts and will be more alert to changes.

3. Have your breast examined by a healthcare provider at least once every three years after age 20, and every year after age 40. Clinical breast exams can detect lumps that may not be detected by mammogram.