Researchers say a drug developed several years ago reduces the chance that older women will get breast cancer for a second time.
The drug is called letrozole. It suppresses the production of the female hormone estrogen. Cancerous growths need estrogen to spread.
Breast cancer is most treatable early in its development. Current practice calls for doctors to operate to remove the growth. Then women take chemotherapy drugs to kill any cancer that remains. After that, women are supposed to take the drug tamoxifen (ta-MOX-i-fen) for five years. This is to prevent the cancer from coming back. But tamoxifen seems to lose its effect after five years.
Researchers have found that fifteen to thirty percent of patients get breast cancer again within ten years after they stop the tamoxifen. These are the women that doctors hope the new drug can help.
Novartis Pharmaceuticals makes letrozole under the name Femara. The drug is already approved in the United States to treat late forms of breast cancer.
The new study involved more than five-thousand women in the United States, Canada and Europe. All had breast cancer once and been treated with tamoxifen. For the study, half took letrozole once a day. The others took a placebo, a pill they did not know contained only sugar.
In all, two-hundred-seven women got breast cancer for a second time. Of these, one-hundred-thirty-two had taken the placebo. Seventy-five had been given letrozole.
The Canadian-led study found that the drug reduced the chance of cancer returning by forty-three percent. The researchers planned to study the women for five years. But they stopped after two-and-a-half years. They said the effect was so clear, it would have been wrong to keep the drug from the other women in the study.
Because of the lack of estrogen, the women on letrozole had a higher risk of bone-thinning osteoporosis. They were also more likely to experience effects similar to those of menopause, like feeling hot all of a sudden.
Ending the study early left some questions unanswered -- for example, how long should women take the drug. The study involved the National Cancer Institutes in Canada and the United States.