Results from two clinical trials show that patients with early-stage breast cancer who received trastuzumab (Herceptin) in combination with chemotherapy had a 52 percent decrease in risk for breast cancer recurrence, compared with patients who received the same chemotherapy without the drug. The difference is statistically highly significant.
Dr. Edward Romond, associate professor of medicine at the University of Kentucky College of Medicine and UK Markey Cancer Center, acts as principal investigator on the study and the National Surgical Adjuvant Breast and Bowel Project (NSABP) study chair.
"For women with this type of aggressive breast cancer, the addition of trastuzumab to chemotherapy appears to virtually reverse prognosis from unfavorable to good. We owe a huge debt of gratitude to the women whose participation in these trials has made it possible to show the substantial benefit of combining trastuzumab with chemotherapy for adjuvant treatment of women with HER-2 positive breast cancer," said Romond.
The clinical trials were sponsored by the National Cancer Institute (NCI), part of the National Institutes of Health, and conducted by a network of researchers led by NSABP and the North Central Cancer Treatment Group (NCCTG), in collaboration with the Cancer and Leukemia Group B, the Eastern Cooperative Oncology Group, and the Southwest Oncology Group. Genentech Inc., which manufactures trastuzumab as Herceptin, provided the drug for the trials under the Cooperative Research and Development Agreement with NCI.
Information from over 3,300 patients enrolled in the studies was used for analysis. Patients with operable breast cancer, whose tumors over-expressed HER-2, were enrolled in these studies between February 2000 and April 2005. Patients are considered "HER-2 positive" if their cancer cells "overexpress," or make too much of, a protein called HER-2, which is found on the surface of cancer cells. Trastuzumab slows or stops the growth of these cells, and it is only used to treat cancers that overexpress the HER–2 protein. Approximately 20 percent to 30 percent of breast cancers overexpress 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 an example of a "targeted" therapy -- an agent that is directed against a specific change in the cancer cell. Trastuzumab was approved for the treatment of advanced breast cancer in 1998.
An estimated 211,240 women will be diagnosed with breast cancer in the United States in 2005. Of these, about 30 percent have lymph node-positive breast cancer, and about 20 percent to 30 percent of these tumors overexpress the HER-2 protein, the target for trastuzumab. Breast cancer is the most commonly diagnosed cancer in women and the second leading cause of cancer-related death in women in this country. An estimated 40,110 deaths from female breast cancer will occur in 2005 in the United States, accounting for about 15 percent of all cancer-related deaths in women in the nation.