Advances in chemotherapy are proving a life-saving boon for women whose breast cancer has spread to the lymph nodes but who have tumors that are not fueled by estrogen, a study said on Tuesday.

At the same the time the study found that women who have the more common kind of tumor, whose growth is affected by estrogen, are helped by the drug tamoxifen but may get only modest benefits from chemotherapy.

The findings, published in this week’s Journal of the American Medical Association, were based on an analysis of three major clinical trials of breast cancer treatment done during the past 20 years.

Researchers at the M.D. Anderson Cancer Center in Houston who led the study said they found that chemotherapy works much better than many people had believed in breast cancer tumors that are so-called estrogen receptor-negative.

At the same time they found it does not work as well as believed for tumors that are estrogen receptor-positive - which make up most breast cancer cases.

Dr. Donald Berry, lead author of the study, said the finding would surprise many tumor experts. Women with estrogen-positive tumors routinely are given chemotherapy as well as tamoxifen, which inhibits estrogen use by cancer cells.

“Our analysis shows that tamoxifen works very well for a number of years and taken as a group, there is little or no benefit of even the cumulative effects of modern improvements in chemotherapy for women with (positive) tumors,” he said.

“All in all, this is good news because it shows that the benefit of chemotherapy for (negative) tumors is surprisingly dramatic in the same way that tamoxifen’s effect is substantial for (positive) tumors,” he added.

The researchers said that although patients with positive breast tumors may opt for chemotherapy, they should recognize that the benefits are not great as compared with those for patients with negative tumors.

“The benefits of intensive and extensive chemotherapy for ... patients who have (positive tumors) treated with tamoxifen are modest at best. Whether such patients should opt for chemotherapy will depend on their attitudes toward the associated negative (side effects),” the report added.

For patients with negative tumors “the overall disease-free survival and overall survival benefits of modern intensive and extensive chemotherapy ... are substantial,” it added.

SOURCE: Journal of the American Medical Association April 12, 2006