ScienceDaily (Oct. 20, 2005) — In a joint paper, co-authored by Mayo Clinic's Edith Perez, M.D., and Edward Romond, M.D., of the National Surgical Adjuvant Breast and Bowel Project (NSABP), researchers report complete and combined results of two trials comparing adjuvant chemotherapy with or without concurrent trastuzumab treatment in women with surgically removed HER2-positive breast cancer. The studies showed trastuzumab (Herceptin®) therapy to be highly superior to standard treatment, reducing recurrence of cancer by half. The findings will be published in the Oct. 20, 2005, issue of The New England Journal of Medicine.

"Herceptin has changed the treatment of breast cancer," says Dr. Perez, who is the co-director of Mayo Clinic's Multidisciplinary Breast Clinic in Jacksonville, Fla. "When we started this study, I knew in my heart results would be positive, but this by far exceeded my expectations."

Of the 2,043 patients enrolled in NSABP trial B-31 and 1,633 patients enrolled in the two reported treatment groups of the North Central Cancer Treatment Group (NCCTG ) trial N9831 by the end of 2004, complete follow-up information was available on 3,351 patients. Two hundred sixty-one women in the control group (1,679 patients) had a recurrence of breast or other primary cancer as compared to 133 in the group receiving trastuzumab. At three years, 90.4 percent of women receiving trastuzumab were disease free, compared to 81.5 percent of women in the control group. There also was a measurable reduction in the development of other non-breast primary cancers in the B-31 trial for women receiving trastuzumab. Overall survival also appeared to be impacted, with only 62 deaths in the trastuzumab group as compared with 92 in the control group.

Dr. Perez and her co-investigators found convincing evidence that women with HER2-positive breast cancer can now be treated more effectively. "A million women each year are diagnosed with breast cancer throughout the world, and approximately 25 percent of them have HER2 tumors," said Dr. Perez. "To be able to find a treatment that impacts the lives of so many is a huge success for the cancer research community."

The NCCTG trial N9831, of which Dr. Perez was the primary investigator, was a cooperative effort with the Eastern Cooperative Oncology Group (ECOG), the Southwest Oncology Group (SWOG), and the Cancer and Leukemia Group B (CALGB). It compared three chemotherapy regimens, two that included trastuzumab therapy -- one dosage concurrent with weekly paclitaxel, the other after completion of paclitaxel. The NSABP trial B-31 compared one chemotherapy regimen against the same regimen with weekly trastuzumab and tri-weekly (or weekly) paclitaxel. Investigators determined that the treatments being compared were similar, and results from the two studies were combined to form a joint analysis, excluding the NCCTG N9831 trial group that looked at trastuzumab administered sequentially after paclitaxel.

In addition to Dr. Perez, members of the NCCTG and Mayo Clinic research team included Vera Suman, Ph.D.; Thomas Pisansky, M.D.; Leila Kutteh, M.D.; Daniel Visscher, M.D.; Robert Jenkins, M.D., Ph.D.; Shaker Dakhil, M.D.; Wilma Lingle, Ph.D.; and James Ingle, M.D. Other collaborating researchers on N9831 included Nancy Davidson, M.D. (ECOG); Silvana Martino, D.O. (SWOG); and Peter Kaufman, M.D. (CALGB).

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The National Institutes of Health provided the majority of funding for this research, with additional support from Genentech, manufacturer of Herceptin®, and the Breast Cancer Research Foundation.

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Adapted from materials provided by Mayo Clinic.

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