WEDNESDAY, Oct. 19 (HealthDay News) — Women who have a particularly aggressive form of breast cancer reap significant benefits when their treatment includes a one-year course of the drug Herceptin.
In international and North American trials, the intravenous drug cut the risk of recurrence of disease by half and markedly improved survival, according to a report in the Oct. 20 issue of the New England Journal of Medicine.
Since these results were first reported last spring at the annual meeting of the American Society of Clinical Oncology, breast cancer oncologists have altered the way they treat early-stage HER2-positive breast cancers.
“Herceptin is now being incorporated in the treatment regimen,” said Dr. Larry Norton, deputy physician-in-chief for Breast Cancer Programs at Memorial Sloan-Kettering Cancer Center in New York City. “The big change is the application of the drug earlier on in the disease.”
Dr. Harold J. Burstein, assistant professor of medicine at Dana-Farber Cancer Institute in Boston, said the studies make it clear that women who have HER2-positive breast cancers should consider using this drug. “Women with this kind of breast cancer get dramatic benefit from adding Herceptin to chemotherapy,” he said.
HER2-positive breast cancers occur when the body makes too many copies of the “human epidermal growth factor receptor 2″ gene and, as a consequence, produces an excess amount of the HER2 protein on the surface of cancer cells. These two actions lead to the particularly aggressive growth and proliferation of these tumors, Burstein explained.
Herceptin, also known as trastuzumab, works by halting the growth of those cancer cells. It is currently approved for the treatment of HER2-positive breast cancer that has spread to other parts of the body.
But the new results show that women with early-stage breast cancer — before it metastasizes, or spreads to other parts of the body — realize enormous benefits as well.
The international trial examined the effects of giving Herceptin after breast cancer surgery, any radiation that might be required and chemotherapy. HER2-positive women were randomly assigned to receive either observation alone or one or two years of the drug. Treatments were administered every three weeks, with striking results.
“At a point early on in the course of the disease, trastuzumab approximately halved the risk of the recurrence of the tumor,” said Richard D. Gelber, a professor in the Department of Biostatistics and Computational Biology at Dana-Farber Cancer Institute, and one of the authors of the study.
That reduction in risk was relative to recurrences among the observation group, he said.
Results for the group of women assigned to receive two years of the drug have yet to be released. For the time being, oncologists don’t really know whether two years of Herceptin therapy would work better than one.
In the North American study, which combined the results of two similar trials, Herceptin was administered along with chemotherapy, not afterward as in the international trial.
The concurrent approach proved highly effective. Herceptin treatment was associated with a 33 percent reduction in the risk of death and an absolute reduction in the proportion of women who were alive and disease-free at three years of 11.8 percentage points.
At four years, the absolute difference in survival between the treatment and control groups was 18 percentage points, “which is really striking,” noted study co-author Dr. Charles E. Geyer Jr., director of medical affairs for the National Surgical Adjuvant Breast and Bowel Project. “We’re not used to seeing that kind of large, dramatic step from the addition of one therapy like this,” he said.
Overall, Herceptin boosted the chances of disease-free survival by 52 percent compared with the control group.
On the downside, Herceptin use carries a risk of potential heart problems, a problem the U.S. Food and Drug Administration warned about in August. While the risk is low, it remains a legitimate concern.
“There still are a handful of women who will suffer cardiac damage from this and you can’t ignore that,” Burstein said. “Hopefully, we will determine which patients are likely to have major problems and which are not so that we can screen patients better and follow them in a more tailored fashion.”