Less Toxic Treatment for Aggressive Breast Cancers?
Newer Chemo Regimen, With Added Herceptin, May Be Less Damaging to the Heart
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Adding Herceptin to Chemotherapy continued...
The study found that adding Herceptin increased the odds that a woman would still be alive and cancer-free more than five years after treatment. It didn't seem to matter whether she was on the standard, more toxic regimen or the newer, less toxic drugs.
Overall, 87% of the women on the standard, three-drug combination were still alive and 75% were cancer-free more than five years later, while 92% of the women were still alive and 84% were cancer-free when Herceptin was added to that treatment.
Of the women on the newer, two-drug regimen with added Herceptin, 91% were still alive and 81% were cancer-free more than five years later.
The differences between the two groups that got Herceptin were not statistically significant.
The benefit for Herceptin was seen whether tumors were small or large and even in women who had positive lymph nodes, indicating that their cancer had spread.
Fewer Side Effects
The biggest difference came when researchers looked at side effects patients experienced.
Patients on the newer, two-drug combination had less joint and muscle pain, less irritation and peeling of the skin and mucous membranes, and less vomiting. There were also fewer reports of low white blood cell counts in the group on the two-drug regimen.
Seven patients on the three-drug regimen developed leukemia, compared to one patient on the newer regimen, but that patient had received another drug, an agent linked with leukemia, outside the study to treat another cancer that arose after her breast cancer.
There was more heart failure in patients treated with Herceptin. But the incidence of heart failure was five times higher in the patients taking the standard three-drug regimen that included Herceptin. Overall, 2% of those patients had heart failure compared to those on the newer drugs with Herceptin. Just 0.4% in that group was diagnosed with heart failure.
What's more, about twice as many patients (18.6% vs. 9.4%) developed heart damage that didn't cause symptoms in the group taking the standard three-drug combination plus Herceptin compared to the newer two-drug combination with Herceptin.
"There's been only one significant problem with Herceptin, and that significant problem is that it increases cardiac toxicity by about four- to fivefold when it's given with anthracycline," says researcher Dennis Slamon, MD, PhD, director of clinical and translational research at the Jonsson Comprehensive Cancer Center at the University of California, Los Angeles.
"You get comparable efficacy, but a dramatically significant difference in some of the acute and chronic toxicities," when a different chemotherapy regimen is used, Slamon tells WebMD.
"The mainstay of breast cancer chemotherapy has been anthracyclines not just in the U.S. but worldwide," he says. "Given the data in this study, it makes one really question what role Adriamycin should play in the treatment of HER-2 positive early breast cancer or in the treatment of early breast cancer at all."
"This trial should impact the way these breast cancers are treated, with a non-anthracycline regimen being our preferred option. I think this is a change that is going to be slow in coming, unfortunately, as many of our ... treatments for breast cancer are built on the backbone of anthracyclines. While they're effective, whatever gain patients may receive is more than made up for in the serious and chronic long-term side effects."