Genetic study questions breast cancer drug
As many as 20,000 American women with breast cancer could be spared the side effects and cost associated with the drug paclitaxel because their tumors don’t respond to it, according to the results of a genetic study reported Thursday.
Using new techniques to reanalyze a 1994 clinical trial, a team found that only women whose tumors produced a protein called HER-2 responded to the drug. These women had a 40% reduction in the recurrence of their cancer, whereas women who had HER-2-negative tumors received no benefit, the researchers reported in the New England Journal of Medicine.
“The days of ‘one size fits all’ therapy for patients with breast cancer are coming to an end,” Dr. Anne Moore of Weill Cornell Medical College in New York wrote in an editorial accompanying the study.
The team reexamined a study of women whose cancer had spread to nearby lymph nodes but not throughout the body -- a group that makes up about a quarter of the 175,000 women diagnosed with invasive breast cancer in the United States each year. All the women had been given four cycles of the drugs Adriamycin and Cytoxan. Half them received four cycles of paclitaxel, commonly known by its brand name, Taxol. The other half received a placebo.
The study reported an overall benefit from paclitaxel, but techniques were not available then to study the genetic makeup of the tumors. The new team randomly selected 1,500 women who participated in the original study and analyzed breast and tumor tissue to reach the new conclusion.
The researchers are not yet ready to recommend stopping paclitaxel in the women who are HER-2-negative -- about 75% of the patients -- because the study was retrospective and needs to be confirmed.
“We think the stakes are too high” to do so, said the lead author, Dr. Daniel Hayes of the University of Michigan Comprehensive Cancer Center.
Treatment with paclitaxel costs about $7,000, which is usually covered by insurance. About 18% of the women who received paclitaxel in the original study suffered neurological side effects, including persistent numbness and tingling in the hands and feet.
The study was funded by the National Institutes of Health and several breast cancer foundations. Some of the researchers consult for Bristol-Myers Squibb Co., which manufactures Taxol.
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