(Ivanhoe Newswire) -- New evidence has surfaced that further establishes
the link between combined hormone therapy and a higher likelihood of breast
cancer.
In a new study published in the New England Journal of Medicine, researchers
found the number of women with breast cancer dropped significantly after they
stopped using estrogen plus progestin. Furthermore, this drop was not associated
with a decline in the number of women getting mammograms -- a theory some have
put forward to explain the lower rate of cancer.
The Women's Health Initiative (WHI) trial of estrogen plus progestin was
terminated in 2002 because of the discovery of a higher incidence of breast
cancer in the hormone therapy group. After a report on the study was made
public, women across the United States stopped using the therapy. Following
this, the incidence of breast cancer declined nationwide.
To
help explain why, researchers in the NEJM study analyzed the results of the WHI
trial to look for trends in breast cancer diagnoses. They found the number of
cases of breast cancer was about two times higher in the group taking the
therapy than in the control group, but after participants discontinued the
therapy, that risk quickly declined. The results also suggest that termination
of combined hormone therapy may put preclinical breast cancers into regression.
Although some experts have suggested the widespread drop in cancer incidence
after the study may be explained by a decrease in mammograms, the new study
results damage that theory. While the number of women who received mammograms
every year remained the same after they left the study, the number of breast
cancer cases in the group that had received the hormone therapy declined
significantly.
SOURCE: New England Journal of Medicine, 2009;360:573-587
