Individualized Therapy for Breast Cancer

Treatment now can be customized for different types of cancer

"Breast cancer" isn't a single disease. Research over the past several decades shows that breast cancers are many different kinds of tumors, and they respond differently to various treatments. As research continues and new drugs are developed, cancer specialists have many more weapons in their arsenal—both singly and in combination—for fighting breast cancer. The best thing about these new approaches is that they can be individualized for each patient's specific type of cancer.

Physicians now can customize treatment based on:

• The "stage" of the tumor—its size, involvement of lymph nodes or presence of cancer cells in the chest wall or muscles
• Whether the tumor is hormone sensitive or "receptive" (in other words, hormones such as estrogen stimulate the cancer's growth)
• Whether the tumor contains a specific protein that also promotes cancer growth

Treatment also varies based on whether the woman is past menopause and whether she inherited genes that raise her breast cancer risk.

An example of treatment based on the stage of the tumor: For "stage III" breast cancer—tumors larger than 5 centimeters, or multiple cancerous lymph nodes—the most effective treatment usually begins with chemotherapy, followed by mastectomy (surgery to remove the entire breast) and then radiation therapy.

An example of treatment targeted to cancers that are hormone sensitive: Hormone-sensitive tumors test positive for the presence of estrogen and progesterone receptors (ER+ and PR+). They're most common after menopause (though natural estrogen levels decline then, the body keeps producing some estrogen), and are always treated in part by interfering with estrogen stimulation of the cancer.

For premenopausal women, estrogen can be blocked with the drug tamoxifen or the ovaries can be removed to eliminate the primary source of estrogen. For postmenopausal women, the production of estrogen can be blocked.

Tamoxifen has been used as an "anti-estrogen" for the past 30 years. It works by neutralizing the cancer cells’ estrogen receptors, so they can no longer take in the hormone that fuels their growth. In the past decade, scientists have developed and tested a new class of drugs called aromatase inhibitors. Aromatase is an enzyme that helps produce estrogen in postmenopausal women. Aromatase inhibitors, like arimidex (Anastrozole) or femara (Letrozole), block this action.

Taking tamoxifen is like putting a wall of insulation between you and a fire; aromatase inhibitors put out the fire. Sometimes oncologists use a combination of the two approaches, giving tamoxifen for a year or two and then switching to an aromatase inhibitor. Clinical trials have shown that this combination works well.

Cancers also can be "HER2-positive" (HER2+), meaning the cells are coated with a protein that stimulates cancer cell growth. For women with this type of tumor, the drug Herceptin is added to the chemotherapy regimen. Herceptin is an antibody that binds to the HER2 protein, blocking the protein's signals to produce more cancer cells.

Tumors that don't have this protein and are not hormone-receptive are called "triple negative" (ER- PR- HER2-). They respond dramatically to chemotherapy, so shrinking the tumor with chemotherapy before surgery often is the best treatment strategy. The chemotherapy targets both the tumor and any microscopic cancer cells that may have spread into the lymph nodes or other parts of the body. And, if the tumor is larger than 2 centimeters, shrinking it first may make it possible to have a lumpectomy instead of a mastectomy.

Unlike 20 years ago, a breast cancer diagnosis doesn't automatically mean loss of a breast. Lumpectomy is recommended for about two-thirds of newly diagnosed patients today. It is a simpler operation with fewer possible complications than a mastectomy and breast reconstruction.

Some women will still need a mastectomy, depending on the size of the tumor, whether the cancer is in several areas of the breast or is too difficult to access, and other factors such as family history and previous breast cancer. Women who've had radiation previously will need a mastectomy. More and more women today opt for breast reconstruction after this surgery.

An exciting area of breast cancer research today is the potential of preventing recurrence. About 30 clinical trials now under way are searching for a breast cancer vaccine to achieve that goal. Like other vaccines, this one would stimulate the immune system, only the target would be cancer cells instead of a virus or bacterium.

Researchers also are studying the effectiveness of various drugs and combination therapies on the cellular level. This saves time because the scientists actually can see if the cells have responded to a treatment instead of waiting years to chart survival rates. For cancers detected early, the five-year survival rate is now over 90 percent. That's good news for anyone whose life has been touched by breast cancer.

Lehigh Valley Hospital's Breast Cancer Consultative Service, along with your physician, can help you individualize the best treatment for your specific kind of breast cancer.

This page last updated 4/27/10 10:34 AM