You may feel lousy after your first Herceptin treatment, but then it gets easy.

You may feel lousy after your first Herceptin treatment, but then it gets easy.(JEFF J. MITCHELL/GETTY IMAGES)If your cancer tests positive for HER2, you're among the roughly 20% of breast cancer patients whose tumor makes too much of a protein called HER2/neu (human epidermal growth factor receptor 2). HER2-positive tumors often grow and spread more aggressively than other cancers, but there's a very effective drug called trastuzumab (Herceptin) that specifically targets the growth-promoting HER2/neu protein.

What Herceptin treatment feels like
The first time you get a Herceptin infusion (usually delivered by IV during a weekly hospital visit), you may feel like you're coming down with the flu. About 40% of women get chills, fever, nausea, vomiting, headache, and dizziness. But these side effects usually get better after the first treatment and become quite tolerable during the standard year-long therapy.

More about Herceptin

Hair loss is not a problem with Herceptin, but many women take Herceptin along with more standard chemotherapy medicines that do cause you to lose your hair.

Most experiences with Herceptin are much like Hidee Singer's. The 53-year-old Minnetonka, Minnesota, resident took Herceptin for a year—at first with Taxol (paclitaxel), a staple of many chemotherapy regimens, and then by itself—and felt fine except for a little fatigue. "I had no reservations about taking the drug," she says. "I had a fast-growing tumor and was told that cancer could return but that Herceptin would minimize that risk by 50%. Herceptin was probably the easiest part of my treatment."

Heart risks
Julie R. Gralow, MD, director of breast medical oncology at the University of Washington and Fred Hutchinson Cancer Research Center in Seattle, cautions that heart trouble can be a side effect of taking Herceptin, especially if you take it along with certain chemotherapy drugs such as Adriamycin. Your doctor may want to test your heart before putting you on Herceptin and possibly also during the period that you remain on treatment.