Hormone Therapy May Not Need to Be Suspended Before Mammography

Hormone therapy may not need to be suspended before mammography, according to the results of a randomized trial reported in the June 2 issue of the Annals of Internal Medicine.

"Without population-based evidence, some clinicians recommend short-term suspension of hormone therapy to improve the performance of mammography," write Diana S.M. Buist, PhD, MPH, from Group Health Center for Health Studies, University of Washington in Seattle, and colleagues. "Hormone therapy increases breast density, and abnormal screening mammograms are more common among women with denser breasts and among women using hormone therapy."

The goal of this study was to evaluate whether temporarily discontinuing hormone therapy for 1 to 2 months before screening mammography in women ages 45 to 80 years is associated with decreased recall for additional mammographic imaging.

From 2004 to 2007 at an integrated health plan in western Washington, 1704 women ages 45 to 80 years who used hormone therapy at their most recent screening (index) mammography, who were due for screening (study) mammography, and who were still using hormone therapy were assigned to 1 of 3 groups. Participants were allocated by block random assignment, based on breast density and type of hormone therapy, to continuation of hormone therapy (n = 567), to suspension for 1 month (n = 570), or to suspension for 2 months (n = 567) before study mammography.

All mammograms were read by a single radiologist blinded to group assignment. The main endpoint of the study was recall for additional mammographic imaging, and the secondary endpoint was change between the index and study mammograms in mammographic breast density (percentage and dense area).

For women in the no-suspension group, mammography recall rate was 61 (11.3%) of 542 vs 50 (12.3%) of 478 in the 1-month suspension group and 44 (9.8%) of 451 in the 2-month suspension group. The investigators did not identify any subgroups in which brief hormone therapy suspension was associated with a decreased rate of mammography recall.

Changes in percentage of breast density were 0.1% in the no-suspension group, –0.9% in the 1-month suspension group), and –1.5% in the 2-month suspension group. Similar orderly and statistically significant decreases were noted for dense area. Menopausal symptoms increased in women who suspended hormone therapy.

"Brief hormone therapy suspension was associated with small changes in breast density and did not affect recall rates," the study authors write. "No evidence supports short-term hormone therapy suspension before mammography."

Limitations of this study include low participation rate (39% of eligible women) and readings by a single expert radiologist. The findings are only generalizable to women aged 45 to 80 years who have used hormone therapy for at least 1 year.

"Our results also demonstrate a substantial negative effect on women from increased menopausal symptoms," the study authors conclude. "For breast cancer detection and prevention, we need to understand whether women whose breast density changes in response to endogenous exposures (such as parity or cyclical changes) and exogenous exposures (such as various hormone therapy types and doses, tamoxifen, or aromatase inhibitors) may benefit differentially from interventions designed to decrease mammographic breast density."