WEDNESDAY, Dec. 5 (HealthDay News) --Taking the breast cancer drug tamoxifen for a decade, instead of the standard five years, further reduces the long-term chances of recurrence and risk of dying from the disease, new British research suggests.
The increase in benefit is especially noticeable after the 10th year, said study author Richard Peto, a professor of medical statistics and epidemiology at the University of Oxford.
Tamoxifen is widely used for treating estrogen receptor or ER-positive breast cancer in women who are pre-menopausal. ER-positive cancers need estrogen to grow, and the drug blocks the activity of estrogen in the breast.
Currently, tamoxifen is usually given daily for five years after a cancer is treated. Doctors have known that five years is more effective than two, and that it reduces the rate of death from breast cancer by about a third in comparison to not taking it, and that it does so for 15 years after the diagnosis.
In the new study, the researchers wanted to see if longer treatment would be even better. They compared results in women who took tamoxifen for five years and 10 years.
A decade was better.
"It's been one moderate therapeutic advance after another," Peto said.
The new research is to be presented Wednesday at the San Antonio Breast Cancer Symposium and published simultaneously in The Lancet.
In the new study, Peto's team looked at nearly 13,000 women who had already taken the drug for five years.
The women were assigned to continue the drug for another five years or to stop taking it. For the analysis, the researchers focused on the 6,846 women who had ER-positive breast cancer, as the main benefit of tamoxifen is thought to be for them. Of these, about half kept taking the drug and half did not.
After about eight years of follow-up, there were 617 recurrences in the drug group and 711
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