The first comparison of two popular drugs has found that women with incurable breast cancer live a few months longer with one of them, but with more severe side effects.
Experts said the findings, presented Wednesday at a European cancer conference, do not necessarily mean all women with advanced breast cancer should be offered Taxotere, which had a better survival record. However, they said the insight would help patients and doctors weigh treatment options.
"There's a huge amount of evidence that cancer patients have different attitudes to treatment,'' said Kathy Redmond, a patients' advocate based in Milan, Italy. "Different people are willing to trade off quality versus quantity of life. The most important thing is to give people the information and let people have a choice.''
Women given Taxotere survived an average of 15.4 months, while those on Taxol survived an average of 12.7 months, said lead investigator Dr. Peter Ravdin, professor of medicine at the University of Texas Health Sciences Center at San Antonio.
"Although that's a modest difference, for those people who lived longer it was important,'' Ravdin said.
The study involved 449 women with advanced breast cancer which continued to spread despite chemotherapy. Half were given Taxol, or paclitaxel, and half were given Taxotere, or docetaxel. Both medications belong to a class of chemotherapy drugs called taxanes, which are widely used for several types of cancers and are administered by intravenous drip.
The study was paid for by Aventis Pharmaceuticals, makers of Taxotere.
Taxol, developed in the United States from the Pacific yew tree and available since 1992, was the first drug of its type. Taxotere, a synthetic drug, was developed in Europe and made available in 1999.
At least 25 percent of women diagnosed with breast cancer go on to develop metastatic disease, whereby the tumor spreads around the body. Nearly all such patients in industrialized countries will get a taxane during their treatment.
The two taxane drugs work by interfering with cell division, but tests indicate not all cancer cells are equally affected by both agents. There are also differences in the way they are broken down and cleared from the body.
In the study, there was no statistically meaningful difference between the drugs when it came to shrinking tumors. The average time before the breast cancer progressed was 5.7 months for the women on Taxotere, compared with 3.6 months among those on Taxol. The longer survival was noted whether the women were pre-menopausal or post-menopausal, Ravdin said.
However, women who received Taxotere reported more side effects, including loss of strength, abnormal fluid accumulation, diarrhea, vomiting, mouth ulcers, a reduction in infection-fighting white blood cells and more infections.
Among women on Taxotere, 15 percent had fever while their white blood cell counts were low, compared with 2 percent of those treated with Taxol. The side effects mostly disappear shortly after the treatment finishes.
Dr. Martine Piccart, head of chemotherapy at the Jules Bordet Institute in Brussels, Belgium, said the findings were not definitive. Both drugs were used once every three weeks in the study, but doctors have since started to give weekly infusions of Taxol.
Upcoming studies are expected to clarify how the two drugs compare on that basis, said Piccart, who was not involved with the research. Dr. John Smythe, professor of medical oncology at the University of Edinburgh in Scotland, said treating a patient involves more than balancing survival and side effects.
"Some patients may prefer oral drugs, which they can take at home, and some patients travel for hours each time they have to come to the hospital,'' he said. "A one-hour infusion, I warn my patients, means half a day at the hospital. Half a day at the hospital means you are sitting there for hours watching people with cancer, some of them less well than you.''