WEDNESDAY, April 16 (HealthDay News) -- Women who take the drug Taxol weekly after receiving chemotherapy for 12 weeks live longer and live longer without a recurrence of their breast cancer, compared to women who take four taxol treatments every three weeks.

The study also evaluated another drug in the same family, called Taxotere (docetaxel), but found that weekly Taxol (paclitaxel) was more effective.

"The findings suggest that weekly Taxol for 12 weeks is more effective than four cycles of Taxol and should be considered a new standard," said study author Dr. Joseph A. Sparano. The findings are detailed in the April 17 issue of the New England Journal of Medicine.

Prior to this study, four cycles of Taxol was considered the standard, although many oncologists were administering the drug weekly.

"We have been using Taxol weekly for at least a year," said Dr. Kumud Tripathy, a clinical assistant professor of internal medicine at Texas A & M Health Science Center College of Medicine and an oncologist with the Bryan-College Station Cancer Clinic.

Women with breast cancer who receive drugs known as taxanes after standard chemotherapy have a substantially reduced risk of recurrence and of death. The other taxane, Taxotere (docetaxel) is more potent than Taxol.

About a decade ago, a study showed that adding Taxol to standard chemo reduced the risk of breast cancer recurrence. The drug was subsequently approved in the United States, with the standard of care being four doses once every three weeks.

A later study showed that giving the same dosage every two weeks was more effective than every three weeks, so that became common practice.

In the meantime, questions were raised as to whether taxanes were effective for the most common type of breast cancer, or that which is hormone-receptor positive and HER2-negative.

"It raised a lot of concerns," said Sparano, director of breast evaluation center at Montefiore-Einstein Cancer Center in New York City. "People were saying, 'Wait a minute. We thought Taxol was very effective, and maybe it's not as effective as we thought, and are we treating people unnecessarily?'"

Here, Sparano and his colleagues compared the effectiveness of giving standard chemo (doxorubicin and cyclophosphamide at three-week intervals) plus four cycles or doses of Taxol every three weeks versus every week for 12 doses at a lower dose. They also compared Taxol with Taxotere (four cycles every three weeks) or Taxotere given either every three weeks for four treatments or weekly for 12 treatments. The study involved almost 5,000 women.

There were no significant differences in survival between those treated with Taxol and those treated with Taxotere or between the groups treated weekly or every three weeks.

There was no indication that weekly Taxol was less effective in women with hormone-receptor-positive, HER2-negative breast cancer.

"Taxol is effective in patients with one or more common subtypes [of breast cancer] and, if it is going to be used in that population, should be delivered weekly for 12 weeks rather than every three weeks for four treatments," Sparano said.

More information

The National Cancer Institute has more on breast cancer.