THURSDAY, Feb. 24 (HealthDay News) -- The cancer drug Herceptin produces significantly longer disease-free survival in women with an aggressive type of early-stage breast cancer who take the drug for a year after standard chemotherapy, a new study suggests.
After analyzing more than 5,000 women from 39 countries between December 2001 and June 2005, Herceptin appeared to reduce the likelihood of a cancer recurrence by 24 percent, the Italian researchers said.
Herceptin (trastuzumab) is a monoclonal antibody that suppresses the HER2/neu protein, which fuels 20 percent to 30 percent of breast cancers. These so-called HER2-positive cancers tend to be aggressive and fast-growing.
"We were inclined to consider the possibility that long-term exposure to trastuzumab deserved a proper test and might be useful," said study author Dr. Luca Gianni, a researcher at Fondazione San Raffaele in Milan.
But while Herceptin patients in the four-year study experienced longer disease-free survival times than patients in an observation group taking chemotherapy alone, the overall risk of death was similar between the two groups.
Gianni attributed this to the fact that 52 percent of patients from the observation group crossed over to receive Herceptin treatment midway through the research because of the drug's impressive early results.
The study received funding from Hoffman-La Roche, the maker of Herceptin, and is published in the Feb. 25 issue of The Lancet Oncology.
"It is very difficult to account for the bias introduced by the late introduction of trastuzumab in more than half of the patients originally randomized to no therapy," Gianni said. "However, it is reasonable to think that the lack of a measurable improvement of survival in the current analysis was due to the effect of the introduction of trastuzumab therapy in a large proportion of women who selected to cross over to the antibody."
While Herceptin has become standard treatment for women with HER2-positive malignancies, the timing of its use is still much in debate. Editorials accompanying Gianni's study took opposing views, with Finnish researcher Heikki Joensuu contending that administering Herceptin simultaneously with chemotherapy might be more effective.
Belgian researcher Evandro de Azambuja, however, argued that the simultaneous treatments would significantly increase the risk of heart damage, which can be a side effect of both Herceptin and a class of standard chemotherapy drugs called anthracyclines.
"I think that both views are respectable, but not necessarily so diverging as they look at first glance," Gianni said. "One should simply consider that the ideal approach can well be that of combining administration of trastuzumab with chemotherapy . . . but avoiding anthracyclines does not mean to avoid combined chemotherapy. Anthracyclines contribute an added benefit that should be thoroughly weighted against the risk of cardiac events before dismissing the combination just as too toxic."
Dr. Lauren Cassell, chief of breast surgery at Lenox Hill Hospital in New York City, said the study's results met her expectations.
"It's confirmation of the fact that Herceptin is extremely effective in patients who show this protein," said Cassell, who noted that oncologists at her hospital typically administer Herceptin for one year after chemotherapy ends. "It is something routinely being used."
Gianni and Cassell agreed that more research needs to focus on whether Herceptin use should be extended to further improve its effectiveness.
"For how long the trastuzumab should be given is really unclear and difficult to test, but in my view will need to be addressed," Gianni said. "The most important message is that we still are and will continue to learn from continuous follow up of studies . . . about [its] optimal use."
There's more on Herceptin at the U.S. National Library of Medicine.
SOURCES: Luca Gianni, M.D., researcher, Fondazione San Raffaele, Milan, Italy; Lauren Casell, M.D., chief of breast surgery, Lenox Hill Hospital, New York City; Feb. 25, 2011 The Lancet Oncology
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