(Ivanhoe Newswire) -- Postmenopausal women with early-stage breast cancer may be better off if they switch to a different medication instead of staying on tamoxifen.

For more than 20 years tamoxifen has been the standard therapy for treating early-stage breast cancer in postmenopausal women. But since the drug has potential side effects like endometrial cancer, and patients can become resistant to the drug, researchers wanted to know whether switching to anastrozol -- a type of drug called a non-steroidal aromatase inhibitor -- after two to three years on tamoxifen would be more effective than continuing on tamoxifen for five years total.

The new study from Germany shows the switch not only helps women live longer but it also increases their chances of staying cancer free after their first breast cancer treatment.

"A lot of people have been waiting to see whether aromatase inhibitors will show a survival advantage, and I think these data will assure them that five years of tamoxifen is no longer the standard of care," reports lead author Professor Walter Jonat, from the University of Kiel in Germany. "The best treatment for women with hormone-sensitive early-stage breast cancer should include an aromatase inhibitor."

But Dr. Jonat says there are still many questions that need to be answered when it comes to breast cancer treatment. Future research needs to look at the best duration of treatment, whether patients should take tamoxifen or aromatase inhibitors first, and whether any combinations of other drugs might be even better.

SOURCE: The Lancet Oncology, published online Nov.16, 2006