Researchers in the North Central Cancer Treatment Group (NCCTG) have shown that patients who receive trastuzumab at the same time as post-chemotherapy radiation treatments for HER-2 positive breast cancer have no more risk for major side effects or complications than those who do not receive the drug. Mayo Clinic's Michele Halyard, M.D., presented these findings today, June 5, at the 2006 American Society of Clinical Oncology (ASCO) annual meeting in Atlanta.

This study resulted from NCCTG clinical trial N9831, from which breakthrough treatment findings were presented at ASCO 2005. "The original N9831 study showed that trastuzumab reduced the recurrence of HER-2 positive breast cancer about 50 percent," says Dr. Halyard, a radiation oncologist at Mayo Clinic Arizona and lead author of today's study. "We hoped also to show that trastuzumab did not add complications to radiation treatment, and the current study has certainly proven that, providing good news for many women."

About 25 percent to 30 percent of breast cancers produce an overabundance of a growth-promoting protein called human epidermal growth factor receptor (HER-2). These tumors tend to grow faster and are generally more likely to recur than tumors that do not overproduce HER-2. Trastuzumab is the first identified monoclonal antibody designed specifically to attack this overexpressed protein, and is used as a follow-on treatment to chemotherapy. A monoclonal antibody is a laboratory-engineered protein that helps the body's immune system fight foreign invaders such as cancer.

Dr. Halyard's study looked at the side effects related to adding trastuzumab to radiation therapy. In the 1,460 patients who received radiation in the original N9831 group, there was no significant difference in the incidence of skin reactions, pneumonitis, dyspnea, cough, esophageal dysphagia or neutropenia between those who received trastuzumab (908), and those who did not (552). Additionally, the researchers report that within the group of 1,286 patients who received trastuzumab, those who had radiation (908) were no more likely to have cardiac complications than those who did not (378).

The NCCTG trastuzumab trial was led by Mayo Clinic Jacksonville's Edith Perez, M.D., with Dr. Halyard as a co-investigator. It was a cooperative effort with the Eastern Cooperative Oncology Group (ECOG), the Southwest Oncology Group (SWOG), and the Cancer and Leukemia Group B (CALGB). Study co-investigators included Mayo Clinic Rochester's Thomas Pisansky, M.D.; and Amylou Dueck, Ph.D.; along with Lori Pierce, M.D., University of Michigan; Lawrence Solin, M.D., University of Pennsylvania; and Lawrence Marks, M.D., Duke University.

Elizabeth Zimmermann
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