Some women under age 64 who ditched hormone replacement therapy (HRT) because of its potential links with breast cancer also stopped screening mammography, researchers found.
Women ages 50 to 64 had lower breast cancer screening rates after they stopped taking HRT, Nancy Breen of the National Cancer Institute in Rockville, Md., and colleagues reported online in Cancer.
Yet there was no association between HRT and mammography screening in women 65 and older, they wrote, indicating that "age was strongly associated with mammography use."
In 2005, mammography rates in the United States dropped for the first time among eligible women. The increased risk of cancer related to hormone therapy detected in the Women's Health Initiative had been reported just three years earlier, in 2002, leading to a significant decline in use by 2005, the researchers said.
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Screening likely declined as well because women on therapy needed to consult their physicians to renew their prescriptions; doctors, in turn, probably used that consultation to talk about the benefits of screening mammography. Fewer visits led to fewer opportunities for discussion, Breen and colleagues said.
So to examine whether the declines in hormone therapy and screening mammography were related, the researchers looked at data from the 2000 and 2005 National Health Interview Survey (NHIS) on over 14,000 patients.
They found that women ages 50 to 64 were more likely to report a recent screening mammogram if they had higher levels of education; had a usual source of care; were covered by private health insurance; were any race except Asian; talked with a doctor in the last year; or were currently on HRT.
Women 65 and older were more likely to report having been screened if they were younger (age 65 to 74); had more education; had a usual source of care; were on Medicare Part B or another supplemental Medicare insurance; were in excellent health; were any race except Asian; had spoken with their doctor in the last year; or were currently taking HRT.
Breen and colleagues said these factors explained 70 to 80 percent of the change in screening mammography use.
The researchers said there was no significant interaction between current HRT use and the survey year, which suggested that HRT and breast cancer screening were related, at least in women ages 50 to 64. In this group, those who stopped HRT had lower screening rates after quitting than when they were on the therapy, the researchers said.
Ultimately, they reduced their screening mammography compliance to rates of those previously observed in women who didn't use hormone therapy, they added.
For women 65 and up, however, hormone therapy use and screening mammography weren't related, the researchers said. Those currently on HRT had lower rates of mammography in 2005 than in 2000. Those who didn't currently use HRT had similar rates of the breast cancer screening test in 2005 and 2000.
That suggests the "change in hormone therapy use had less effect on mammography use in older women compared with younger women."
Though the study was limited by self-reported data, Breen and colleagues concluded that the findings are "consistent with the preponderance of evidence from other studies indicating that the decline in incidence [in breast screening] is accounted for largely by a reduction in risk caused by hormone therapy cessation."
The findings also "continue to raise the possibility that reduced mammography use may also have played a role in the relation between hormone therapy and [breast cancer] incidence in the population."