WASHINGTON — Menopausal women who took estrogen and progesterone faced a small increased risk for cancer for more than two years after they stopped, according to the latest results of a major federal study that has revealed a series of sobering findings about the once-popular hormone therapy.
The study of more than 15,000 women who took the hormones for more than five years found that the chance of developing cancer remained elevated well after they quit, which many did after an earlier stage of the study showed that the risks outweighed the benefits.
While their increased risk of heart attacks, blood clots and strokes appeared to vanish as soon as women got off the drugs, the cancer risk persisted. It appeared to be driven primarily by a continued increased rate of breast cancer but also by a new, unexpected higher risk of other malignancies, such as lung cancer, the analysis found.
“The question has been: Do the risks persist?” said Marcia Stefanick of Stanford University, who chairs the steering committee for the federally funded Women’s Health Initiative. “What this clearly shows is, unfortunately, the risk for cancer continues.”
Stefanick said the data appeared to show a real trend even though the breast cancer difference was not statistically significant, but other experts warned that finding could have been due to chance.
All the same, the findings underscore the now-standard recommendation that women who take hormones to relieve hot flashes and other effects of menopause should use the lowest possible dose for the shortest time. Stefanick said. And the millions of women who have taken the hormones should be monitored closely for cancer, especially breast cancer, she said.
“The important message is women really need to make sure they continue getting their mammograms,” Stefanick said.
It remains unclear how long the increased risk persists, she said, and researchers have continued following the women to try to answer that crucial question.
It is also unclear whether women who took the hormone combination for shorter periods or took estrogen alone face similar ongoing risks.
The study involved 15,730 postmenopausal women ages 50 to 79 who took estrogen and progesterone for an average of 5.6 years.
