Hormone-replacement therapy given to women diagnosed with invasive breast cancer is associated with a lower risk of breast cancer recurrence, breast cancer death and overall mortality, according to research by Hutch investigators in the Public Health Sciences Division.
However, the researchers caution that the results are preliminary and that the role of estrogen in breast cancer is complex and poorly understood.
The study, led by Dr. Ellen O'Meara and published in the May 16 issue of the Journal of the National Cancer Institute, included Drs. Janet Daling, Mary Anne Rossing and Noel Weiss in the Hutch's Epidemiology Program. O'Meara is now part of the Cardiovascular Health Study at the University of Washington.
Investigators from the UW and Group Health Cooperative of Puget Sound collaborated on the project.
HRT is typically avoided in women who have had breast cancer because of concern that estrogens might stimulate recurrence. The new research shows that HRT users had about half the risk of breast cancer recurrence as nonusers, one-third the risk of death from breast cancer and half the risk of death from any cause.
Some 170 women age 35 to 74 diagnosed with breast cancer from 1977 through 1994 who took HRT after diagnosis were compared with nonusers of similar age, disease stage and year of diagnosis.
Authors observed lower risks of recurrence and mortality in women who used HRT after breast-cancer diagnosis than in women who did not. But because the study showed that the risk of developing breast cancer in the unaffected breast was higher among women who used HRT after the initial diagnosis, the authors caution that overall impact of HRT after cancer must be carefully evaluated.