Biological Therapy for Breast Cancer

Biological therapy for breast cancer takes advantage of the body's own immune or hormonal system to act on cancer cells - while leaving healthy cells relatively intact. This approach is designed to minimize the side effects associated with traditional treatments like chemotherapy.

One strategy is to use antibodies to attack cancer cells or block their activities. An antibody is a protein that can attach to specific proteins in the body, called antigens. Antibodies can be natural, made by one's own immune system, or made artificially. One example of a manufactured antibody is trastuzumab, or Herceptin.

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 a drug called Taxol (paclitaxel).

Another form of biological therapy is the use of drugs composed of small molecules the interrupt the hormonal or chemical pathways that cancer cells need to grow. Lapatinib, or Tykerb, is an example of a small molecule that is used in combination with chemotherapy to treat some advanced cases of breast cancer.

One disadvantage of antibody treatment is that it is generally only available by injection. Small molecule treatment can be taken in pill form.

Other types of antibodies and small molecules that are being researched to fight breast 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 of Biological Therapy

Side effects of biological therapy 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 about your cancer 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, a 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 heartburn; nausea, vomiting, constipation, or diarrhea that lasts longer than two or three days; or blood in stools.