Yew drugs show their mettle.

Taxol, a compound derived from the bark of the Pacific yew, may be a useful first chemical defense against tumors as well as a last-resort cancer treatment. Five studies conducted in recent years show that taxol can cause remission of breast and ovarian tumors unresponsive to other drugs (SN: 2/22/92, p.124; 4/18/92, p.244). Now, researchers are finding that for ovarian cancer, taxol works better than the standard drug treatment.

In a study involving 388 women with ovarian cancer, tumor tissue shrank or disappeared in 73 percent of women taking taxol and cisplatin, compared with 59 percent of those receiving cytoxan and cisplatin, reports William P. McGuire III of the Johns Hopkins Oncology Center in Baltimore. On average, tumors took three months longer to reappear in women treated with taxol than in those receiving the other regimen. "This should become the standard of care for this group of patients," he concludes.

Some have expressed concern about side effects -- notably numbness or tingling in toes and fingers and a reduction in infection-fighting blood cells -- due to taxol's effect on bone marrow. But McGuire and others point out that these effects can be managed with other medications and that taxol is often tolerated better than many cancer drugs now in use.

For example, in a new study conducted by Charles Link and his colleagues from the National Cancer Institute in Bethesda, Md., bone marrow in 48 women fared better after prolonged treatment with taxol when the patients received a growth factor at the same time. These women suffered from ovarian cancer that did not respond to other drugs. The growth factor, a protein called granulocyte colony stimulating factor, protected bone marrow, so the women maintained adequate numbers of white cells and platelets despite a near doubling of the taxol dose and more than a year of taxol therapy, says Link.

Several groups are testing another yew compound, this one derived from the harvested needles. Pierre Fumoleau of the Nantes (France) Cancer Center and his colleagues observed a 73 percent response in 33 patients with advanced breast cancer who received this experimental drug, known by the brand name Taxotere. Dutch and Canadian researchers also report that Taxotere proved very active against breast cancer.