Posted on 03/10/2004 11:13:41 PM PST by neverdem
Drugs that completely block estrogen can lower the risk of breast cancer recurrence in postmenopausal women after surgery, according to the latest study to suggest that some women can improve their chances of recovering from breast cancer with aromatase inhibitors.
The study followed more than 4,700 women who took tamoxifen, the most common treatment for preventing recurrences of breast cancer. But women who switched to the estrogen-blocker exemestane two and a half years later cut their chances of developing another tumor by a third.
Taking exemestane, which is sold under the brand name aromasin by Pfizer, also provided better protection against developing a tumor in the second breast and carried less severe side effects than tamoxifen.
The most serious known risk of aromasin and other aromatase inhibitors is bone loss, a concern for patients with a history of osteoporosis, said Dr. R. Charles Coombes, the study's lead author. One solution, he said, might be to combine the therapy with calcium supplements.
The researchers also warned that it was unclear if postmenopausal women should switch to aromasin.
"It seems that the beneficial effects are partially the result of two to three years of tamoxifen first, so at the moment it appears that both drugs should be given in sequence," said Dr. Coombes, a professor of cancer medicine at Imperial College School of Medicine in London.
The findings, to be published today in the New England Journal of Medicine, were released a year ahead of schedule. But the study is continuing, its authors said, and it is uncertain whether the drug can save lives.
Women are usually advised to take tamoxifen for five years after a breast cancer operation. But half of all recurrences occur five or more years after cancer is first diagnosed, and continuing tamoxifen provides no added protection.
Aromasin is one of several drugs that suppress blood levels of estrogen by blocking aromatase, the enzyme that helps to produce it. By choking off the body's main source of estrogen, aromasin and other aromatase inhibitors cut estrogen levels to almost zero.
Tamoxifen prevents estrogen from latching onto tumor cell receptors and directing them to multiply. In some patients the drug's effectiveness fades, and serious side effects can result, including uterine cancer.
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