Breast cancer patients taking the drug tamoxifen can cut their chances of having the disease come back or kill them if they stay on the pills for 10 years instead of five years as doctors recommend now, a major study finds.
The results could change treatment, especially for younger women. The findings are a surprise because earlier research suggested that taking the hormone-blocking drug for longer than five years didn’t help and might even be harmful.
In the new study, researchers found that women who took tamoxifen for 10 years lowered their risk of a recurrence by 25 percent and of dying of breast cancer by 29 percent compared to those who took the pills for just five years.
In absolute terms, continuing on tamoxifen kept three additional women out of every 100 from dying of breast cancer within five to 14 years from when their disease was diagnosed. When added to the benefit from the first five years of use, a decade of tamoxifen can cut breast cancer mortality in half during the second decade after diagnosis, researchers estimate.
Some women balk at taking a preventive drug for so long, but for those at high risk of a recurrence, “this will be a convincer that they should continue,” said Dr. Peter Ravdin, director of the breast cancer program at the UT Health Science Center in San Antonio.
He reviewed results of the study, which was presented Wednesday at a breast cancer conference in San Antonio and published by the British medical journal Lancet.
“The result of this trial will have a major, immediate impact on premenopausal women,” Ravdin said.