Biological Therapy for Breast Cancer: Herceptin & Antibodies

Biological therapy uses the body's own immune system to act on cancer cells - while leaving healthy cells unaffected. Theoretically, this approach minimizes side effects. Many of these treatments are still experimental. The idea is to use antibodies to attack cancer cells.

One such antibody is Herceptin, which is a monoclonal (meaning single) antibody. An antibody is a protein made by the body's own immune system. Herceptin is believed to act in three ways to stop cancer cells from growing quickly and out of control:

• It sticks to special receptors on the cancer cells, stopping them from growing.
• It signals the body's own natural killer cells to attack the cancer cells.
• It can work with chemotherapy medications, stopping cancer cells damaged by chemo from repairing themselves.

But Herceptin can work only if the woman carries the HER-2 gene in those tumor cells. About 25% of breast cancer patients carry this gene. (They are considered HER-2 positive). It currently is the first-line treatment of HER-2-positive metastatic breast cancer in combination with Taxol (paclitaxel).

Other types of antibodies that are being researched to fight cancer include:

• Angiogenesis inhibitors. These antibodies prevent the growth of new blood vessels, cutting off the supply of oxygen and nutrients to cancer cells.
• Signal transduction inhibitors. These antibodies block signals inside the cancer cell that helps the cells divide, stopping the cancer from growing.

Side Effects

Side effects can include allergic reactions, difficulty breathing, swelling, nausea, fever or chills, and dizziness or weakness. Talk to your doctor about the possible side effects to watch for.

Recognizing a Cancer Emergency

Call your nurse or doctor if you have:

• A temperature greater than 100 F. If you experience any fever and chills, notify your doctor immediately. If you are unable to contact your doctor, go to the emergency room.
• If you notice in your mouth new sores, patches, swollen tongue or bleeding gums.
• If you experience a dry, burning, scratchy, or "swollen" throat.
• A cough that is new or persistent and produces mucus.
• Changes in bladder function, including increased frequency or urgency to go; burning during urination; or blood in your urine.
• Changes in gastrointestinal function, including heart burn; nausea, vomiting, constipation, or diarrhea that lasts longer than two or three days; or blood in stools.