An experimental chemotherapy drug called Abraxane was more effective in treating advanced cases of breast cancer and carried fewer side effects than its widely used cousin Taxol, according to a study.
In another chemotherapy-related study released Friday, the drug docetaxel - widely used for late-stage breast cancer since the mid-1990s - was found to be dramatically better at battling a common early-stage form of the disease than fluorouracil, long a standard treatment.
Research by the Breast Cancer International Research Group determined that five years after initial treatment, the docetaxel patients had a 28 percent lower risk of recurrence than the fluorouracil patients.
"I think this will be convincing to a lot of doctors," said Dr. John Mackey, a breast cancer specialist at the University of Alberta in Canada and a co-leader of the study. "People change their (drug recommendations) based on a 2 to 3 percent improvement."
A study involving 454 women with breast cancer that had spread elsewhere in the body found that 33 percent of tumors responded to Abraxane, compared with 19 percent for Taxol. Abraxane also slowed tumor growth significantly in those patients.
The studies were outlined at a breast cancer conference in San Antonio.
Both Taxol and Abraxane are derived from paclitaxel, which works by interfering with a cancer cell's ability to divide. A big difference is how they make their way through the body, and thus how large the dosage can be.
Taxol is combined with an oil-based solvent known as Cremophor, whose often harsh side effects limit how much paclitaxel can be delivered to a patient per treatment session.
Abraxane, on the other hand, hitches a ride on the naturally occurring human protein albumin, allowing researchers to administer about 60 percent more paclitaxel per treatment.
This approach "allows us, for the first time, to fully maximize the tried-and-true power of paclitaxel," said Dr. William Gradishar, a Northwestern University medical professor and a co-director of the study.
The research was sponsored by American BioScience Inc., which developed Abraxane.
Neil Desai, research vice president at American BioScience, said Abraxane's delivery system - known as nanoparticle albumin-bound technology - may also be used for other water-insoluble drugs injected into the bloodstream.
The docetaxel study involved nearly 1,500 pre- and postmenopausal women in 20 countries with early-stage breast cancer that had spread into the lymph nodes in the armpit.
After five years, 75 percent of the docetaxel patients had not developed new breast cancer, compared with 68 percent of the fluorouracil patients.
Using statistical analysis, the researchers calculated that the chances of relapse using docetaxel are 28 percent lower than with the other drug.
"These results offer a promising new treatment option for reducing the risk of recurrence and mortality of early breast cancer patients," said Susan Braun, president of the Susan G. Komen Breast Cancer Foundation, based in Dallas.
The study was sponsored by Aventis Pharmaceuticals, which markets docetaxel under the brand name Taxotere.