Drug Can Prevent Breast Cancer, Study Finds By Andrew POLLACK

 Chicago — A drug now used to prevent recurrences of breast cancer can also prevent it from occurring in the first place, providing a new option for women at high risk of getting the disease, researchers reported here on Saturday.

 Two drugs, tamoxifen and raloxifene, are already approved to prevent breast cancer but are rarely used for that purpose, in part because they can have serious side effects like uterine cancer and blood clots. The researchers said the new option, exemestane, does not have those side effects and might be more acceptable.

 “There’s a very safe therapy that looks highly effective in preventing breast cancer,” Dr. Paul E. Goss, professor of medicine at Harvard and Massachusetts General Hospital, said at a news conference at the annual meeting of the American Society of Clinical Oncology. He was the lead investigator in the study, which is being presented at the conference and published online by the New England Journal of Medicine.

 Two other studies presented at the conference show that the widely used cancer drug Avastin is effective in delaying the progression of ovarian cancer. But both studies so far have narrowly missed showing that the drug can prolong lives, the ultimate test of a cancer drug. That threatens to embroil the use of Avastin for ovarian cancer in a debate similar to the one surrounding its use in breast cancer.

 Exemestane, also known by the brand name Aromasin, is one of a class of compounds known as aromatase inhibitors. These drugs have proven superior to tamoxifen in preventing recurrence of cancer after a breast tumor is surgically removed.

 So researchers have long suspected that aromatase inhibitors would also reduce the risk of an initial occurrence of breast cancer, though this is the first big randomized study to demonstrate that.

 The trial involved 4,560 post-menopausal women in the United States, Canada, France and Spain who were considered to be at a higher than normal risk of developing breast cancer either because of being over 60 or other factors. After a follow-up of about three years, 11 women getting the drug had developed invasive breast cancer compared with 32 of the women receiving a placebo. That is a reduction in risk of 65 percent.

 About 94 women would have to be treated for three years to prevent one case of breast cancer, Dr. Goss said. That is less treatment than the 95 women who have to be treated for a longer time, five years, to prevent one cancer case with tamoxifen, he said. In the trial, exemestane side effects were acceptable, he said. But women who took exemestane had more hot flashes and arthritis than those who had the placebo. Still, whether exemestane will catch on where the other drugs have not remains to be seen.

 One factor working against it is that aromatase inhibitors are now prescribed by oncologists. But for prevention, “They would have to be prescribed by gynecologists and family doctors,” said Dr. George W. Sledge Jr., a breast cancer specialist at Indiana University and the president of the oncology society. “These doctors are not comfortable with these drugs.”

 Another factor is that the patent protection on the drug expired in April. Generic versions will mean much lower prices for women who decide to take it for the recommended five years.

 But generic competition also means that Pfizer, which sells Aromasin, now has little incentive to seek regulatory approval for the drug for preventing breast cancer. Pfizer declined to comment on whether it would seek such approval. Pfizer helped pay for the study, and Dr. Goss has reported receiving honoraria from the company.

 Regarding Avastin, the drug’s manufacturer, Roche, has filed for approval in Europe to market the drug as a treatment for ovarian cancer. But its American subsidiary, Genentech, is still in discussions with the Food and Drug Administration about whether there is enough evidence for an approval. One question is whether it will be necessary to show that the drug prolongs lives, said Dr. Sandra Horning, who runs cancer clinical trials for Genentech. The F.D.A. is now moving to revoke the approval of Avastin for use in treating breast cancer in part because the drug has not prolonged lives in clinical trials. The F.D.A. will hold a hearing on this issue this month.

 One study presented here involved 484 women whose ovarian cancer had recurred after an initial drug treatment. All the women received two standard drugs, and half of them also received Avastin.

 The median time that women lived before their cancer worsened was 12.4 months for those who got Avastin compared with 8.4 months for those who received only the two other drugs.

 After two years, more women who received Avastin were alive, but the difference was not quite statistically significant. Too few women had died to draw conclusions.

 “It really is not appropriate statistically to say we really know anything about overall survival here,” said Dr. Carol Aghajanian of the Memorial Sloan-Kettering Cancer Center, the lead investigator. The trial was sponsored by Genentech.

 The other trial, partly paid for by Roche, involved adding Avastin to the standard drugs used as initial therapy. There were 178 deaths in the Avastin arm and 200 among those who got the standard drugs, a finding that narrowly missed statistical significance. However, in a subset of patients considered to be at higher risk of recurrence, there was a statistically significant improvement in survival.

 Experts say that women with ovarian cancer tend to get many different treatments over time. Many women who did not receive Avastin in a trial might get it after the trial is over. That is one reason that Avastin is not prolonging lives even though it delays the time before tumors start growing again.

 Avastin, also known as bevacizumab, is already widely used off label to treat recurrences of ovarian cancer, based on some smaller earlier trials. But some doctors said the new results might lead them to use the drug earlier in the course of the disease and for longer durations, providing insurers would pay. The drug costs about $88,000 a year, and more in some cases.

 “It creates sort of a conundrum,” said Dr. Robert A. Burger of the Fox Chase Cancer Center in Philadelphia, who was an investigator in a different trial of Avastin presented last year. “And a lot of it is based on the cost of treatment.”

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