The widely used chemotherapy drug Taxol does not work for the most common form of breast cancer and helps far fewer patients than has been believed, surprising new research suggests.
If further study bears this out, more than 20,000 women each year in the United States alone might be spared the side effects of this drug or similar ones without significantly raising the risk their cancer will return. That would be roughly half of all breast cancer patients who get chemo now.
“We want to make sure these data are correct before withholding it (Taxol) from some patients … the stakes are high,” said the lead researcher, Dr. Daniel Hayes of the University of Michigan. “On the other hand, we don’t want to keep a therapy that doesn’t work.”
In the study, Taxol did the most good for women who had overactive HER-2 genes – the target of the newer breast cancer drug Herceptin. These women were about 40 percent less likely to have a recurrence if they received Taxol.
Conversely, Taxol did not significantly help women whose tumors were HER-2 negative and were being helped to grow by estrogen. This is the most common form of the disease.
The differences were revealed by a new analysis of a study done in the 1990s, using modern genetic tools that were not available at that time.
“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 wrote in an editorial accompanying the study in today’s New England Journal of Medicine.
“Oncologists have a responsibility to their patients to be aware of this report.”
Taxol improved survival and became a new standard of care. But the drug frequently causes neurological side effects including numbness and tingling in the hands and feet.