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    Longer Tamoxifen Use Helps Breast Cancer Survival

    Benefits Greatest in the Second Decade After Diagnosis continued...

    “You’re holding down the disease that’s scattered around the body and this produces benefit years and years after the treatment is finished,” Peto says.

    This isn’t the first study to test the effects of longer courses of tamoxifen. Previous studies had mixed results. Some concluded that the additional risks of the drug didn’t outweigh its benefits, but those studies were much smaller and had limited power to see differences between their study groups.

    Peto notes that they did see slightly more cases of uterine cancer and blood clots in women who doubled their time on tamoxifen -- 1.6% of women in the five-year group were diagnosed with uterine cancer compared to 3.1% in the 10-year group.

    There were about twice as many cases of pulmonary embolism, cases where a dangerous blood clot makes its way to the lungs -- 21 in the five-year group as opposed to 41 in the 10-year group. There was no significant increase in stroke risk.

    Study May Herald a Shift in Thinking About All Kinds of Hormone Treatments

    Experts who were not involved in the study said it was likely to have a limited application, partly because newer drugs have displaced tamoxifen in older women and partly because it can be a difficult drug to take.

    “I think there’s a group of women who are very concerned about recurrence and feel that if they can do anything to decrease their risk, that may be worth it for them,” says Jennifer Litton, MD, an assistant professor in the department of breast medical oncology at the University of Texas M.D. Anderson Cancer Center in Houston.

    “Then there are a lot of other patients I have who are having side effects -- hot flashes and other issues -- who are counting the minutes to get off it.” For them, Litton says the additional benefits may not seem worth it.

    Ravdin agrees that continuing treatment is likely to be a highly individual choice.

    But he says the study is also important because of what it seems to signal about the biology of the disease.

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