Switching drug in breast cancer boosts survival

SAN ANTONIO — Women have better odds of surviving early breast cancer if they are switched to a newer drug after two or three years of tamoxifen, doctors are reporting.

It is the first evidence that drugs called aromatase inhibitors can save lives, not just prevent cancer from coming back.

Other new research suggests that the longer women take these drugs, the more they may benefit.

"This is a first attempt to get a grip on duration" of treatment, said the leader of one of the studies, Dr. James Ingle of the Mayo Clinic in Rochester, Minn. "Longer is better."

The findings were reported Friday at a breast cancer conference in Texas.

Tamoxifen has been a mainstay of breast cancer treatment for decades. Taking it for five years after cancer surgery cuts the risk of recurrence in half and improves survival. The drug blunts the effects of estrogen, a hormone that fuels the growth of most tumors that occur in women after menopause.

Aromatase inhibitors keep estrogen from being made in the first place, and do not raise the risk of blood clots and endometrial cancer as tamoxifen does. Three brands are available: AstraZeneca PLC's Arimidex, Pfizer Inc.'s Aromasin and Novartis Pharmaceuticals' Femara.

Doctors already know that these drugs can cut the risk of recurrence, as tamoxifen does, but keeping women alive is the ultimate test any cancer treatment must pass.

Researchers led by Dr. Walter Jonat of the University of Kiel in Germany combined information from three large European studies on Arimidex and found that women who were switched to it after several years of tamoxifen were 29 percent more likely to be alive 2 1/2 years later.

About 4.5 percent of women who continued on tamoxifen died, compared with only 3.3 percent of those who switched to Arimidex. More than 3,800 women were included in the analysis, which was paid for by AstraZeneca, as were the individual studies.

"This is the first time survival advantage has been shown," said Jonat, who has no financial ties to the drug maker.

Women who switched drugs also had a 41 percent lower risk of having cancer again.

Other research reported by Ingle and Dr. Paul Goss of Massachusetts General Hospital involved women taking Femara after they had completed the initially recommended five years of tamoxifen.