Breast Cancer Decline Linked to HRT
Study: Drop in Breast Cancer Rates Related to Decline in Hormone Replacement Therapy
Aug. 14, 2007 -- Breast cancer rates are down, and that's probably because
fewer women are using hormone replacement therapy (HRT) in menopause, a new
The study, published online today in the Journal of the National Cancer
Institute, is the latest entry in a controversy about declining U.S. breast
Some experts say the drop in breast cancer rates is partly due to the fact
that fewer women have been getting routine mammograms to screen for breast
cancer. Without those mammograms, breast cancers may just be going undiagnosed,
or so the theory goes.
Other researchers credit the fact that many menopausal women turned away
from hormone replacement therapy after July 2002. That's when the Women's
Health Initiative, a long-term women's health study, linked HRT to increased
risk of breast cancer.
The new study favors the HRT explanation, not the mammography theory.
The researchers included Karla Kerlikowske, MD, of the University of
California at San Francisco and the San Francisco Veterans Affairs Medical
Kerlikowske and colleagues studied data on more than 600,000 mammograms
performed on U.S. women ages 50-69 between 1997 and 2003.
The researchers picked those years because they span a few years before and
after the Women's Health Initiative findings on breast cancer and HRT came
The study shows a nearly simultaneous drop in the women's HRT use and
estrogen-sensitive breast cancer, which is the kind of breast cancer that's
been linked to HRT use.
For instance, between 2002 and 2003, HRT use fell by 34%. That lines up with
a 13% drop in the women's rate of estrogen-sensitive breast cancer.
The researchers point out that since they only studied women who got routine
screening mammograms, the downturn in breast cancer rates simply can't be due
to missed mammograms.
Why didn't breast cancer rates fall further, given the drop in HRT use?
Perhaps breast cancer risk falls gradually after ceasing HRT, suggest
Kerlikowske and colleagues.
Will this study settle the debate? That remains to be seen, since the topic
is "controversial," as the researchers write.
The drug company Wyeth, which
makes the postmenopausal hormone therapy drug Prempro, emailed WebMD a
statement about the study.
"Wyeth cautions against
drawing the conclusion made by the study authors because the decline in breast
cancer incidence cannot be determined from this type of study and there may be
other factors that could have an impact on breast cancer incidence
rates. In addition, Wyeth notes that the product labeling for Wyeth’s and
other postmenopausal hormone therapies advises about an increased risk of
breast cancer and suggests women taking therapy do monthly breast self exams
and have routine mammography screenings," states Wyeth.