Stunning success halts breast cancer drug trial

TORONTO - A new class of breast cancer drugs has been so successful in an international trial that testing has been stopped to allow all the patients to benefit from the stunning success rate.

The five-year study of about 5200 women with breast cancer was halted midway because Femara, made by Swiss drugmaker Novartis, almost halved the risk of the disease recurring compared with the risk for patients taking a placebo.

"This is a sea change in the treatment of the disease," said research leader Dr Paul Goss of Princess Margaret Hospital, Toronto.

The New England Journal of Medicine released the findings before its November 6 issue because of their significance.

Dr Goss said the "dramatic results" prompted doctors to halt the trial so that nearly 2600 women in the placebo group could start taking the once-daily pill Femara immediately.

Doctors said the study offered a new direction to treat breast cancer, but also raised questions.

"How long should one take [Femara]? What are the long-term toxicities?" said Dr James Ingles, with the Mayo Clinic in Rochester, Minnesota, another participant in the study.

Stopping the trial meant researchers were unable to study Femara's effect over the full five years.

Tamoxifen is the most widely used drug for breast cancer. But it loses its effectiveness after five years, a worry for patients with the disease, which strikes again in one out of two women five years after diagnosis.

The trial offered Femara, whose generic name is letrozole, to women who had been off tamoxifen for less than three months after taking the treatment for five years.

It raised questions about the effectiveness of the new drug for women off tamoxifen for more than three months, and offered no definitive answers for those who have recently been diagnosed and might want to take letrozole.

Letrozole is one of a class of cancer drugs called aromatase inhibitors, which suppress the production of oestrogen.

Half of the women in the blind trial got letrozole and half got a placebo.

After a little more than two years, the cancer returned in 75 of the women who took letrozole, compared with 132 in the group taking the placebo.

The study was conducted in nine countries, including Canada, the United States and England and Belgium.

- REUTERS