Study finds newer breast cancer drugs save lives

WASHINGTON (Reuters) - Women who switch from the breast cancer pill tamoxifen to a newer class of drugs called aromatase inhibitors live longer, Italian researchers reported on Monday.

Their study, published in the journal Cancer, adds to a growing body of evidence that the new drugs are far safer, preventing cancer with fewer side effects than tamoxifen.

Dr. Lauren Cassell of Lenox Hill Hospital in New York said the research is changing how doctors treat breast cancer patients after their tumors are surgically removed.

"If they have been on tamoxifen we are switching them to an aromatase inhibitor. If they are newly diagnosed we are using an aromatase inhibitor instead of tamoxifen," she said in a statement.

But tamoxifen remains the main option for younger women with breast cancer.

"Aromatase inhibitors are only for women who are post-menopausal," Cassell said.

Tamoxifen transformed breast cancer therapy when it was shown to reduce the risk of cancer coming back by close to 50 percent. It was also an easy-to-take pill.

But the drug raised the risk of death from strokes and endometrial cancer.

Then a newer class of drugs, the aromatase inhibitors, was developed.

Dr. Francesco Boccardo of the National Cancer Research Institute and the University of Genoa in Italy and colleagues looked at two studies of 828 women.

About half the women got tamoxifen for five years, as was once recommended, and half got tamoxifen at first and then switched to an aromatase inhibitor after two or three years.

The women who switched were much less likely to die of breast cancer or of anything else, Boccardo reported.

"This pooled analysis provides solid evidence that switching to an aromatase inhibitor following a few years of tamoxifen treatment implies a mortality benefit over continued tamoxifen and that the benefit on breast cancer-related mortality is mainly due to the effect of switching," they wrote.

German researchers reported similar findings in November.

Aromatase inhibitors include anastrozole, made by AstraZeneca Plc under the brand name Arimidex, and exemestane, made by Pfizer Inc. under the brand name Aromasin.

Tamoxifen -- long the drug of choice for preventing breast cancer -- blocks estrogen, which can help fuel the growth of tumors in some cases.