OHSU study suggests that HRT may act on cancer cells to produce less aggressive tumors
A study of nearly 300 breast cancer patients at Oregon Health & Science University found that women who use hormone replacement therapy (HRT) have less aggressive tumors and are more likely to be diagnosed through mammograms than other methods. Also, HRT users with breast cancer had significantly better survival rates than non-HRT users. The study is published in the September issue of the journal The Archives of Surgery.
Because hormones increase the density of breast tissue, researchers have suspected that HRT use would make it more difficult to detect tumors on mammograms. As a result, it was suspected that tumors in patients who have received HRT might not be detected until they were larger and more advanced. However, of 144 study patients using HRT, 84 had their tumors detected by mammogram, while 60 were detected by other methods. Comparatively, of 148 non-HRT users, 63 had their tumors detected by mammogram, while 85 were detected by palpation (feeling for lumps).
Even more surprising, among the women whose tumors were detected by mammogram, HRT users had a 100 percent survival rate, while nonusers had only an 87 percent survival rate after six years. The study found significantly fewer cases of invasive tumors among HRT users, and higher incidences of T1 lesions, stage 1 tumors and node-negative tumors--all signs of a less aggressive disease.
"From this data it appears that HRT use had only beneficial effects on breast cancer detection and outcomes, with no visible negative effects," said Rodney F. Pommier, M.D., associate professor of surgery in the OHSU School of Medicine and principal investigator of the study.
Hormone replacement therapy has come under fire in recent months after several studies indicated that long-term use of combination hormone therapies can lead to slight increases in heart disease, stroke and breast cancer among patients.
"Every woman should talk to her physician about her own risks and benefits of taking hormones," said Pommier. "But this data needs to be taken into consideration as well. If we know that HRT can improve survival rates by producing a less aggressive breast cancer, then it's possible that by withholding HRT for the purpose of possibly preventing a few cases of breast cancer, you're going to have a higher death rate among women who were going to get the disease anyway."
The Women's Health Initiative last July canceled its clinical trial on the use of combination estrogen-progestin HRT due to higher reports of associated illnesses. However, there has not been the same association with estrogen-only HRT. The OHSU study, which was a retrospective analysis of patients already diagnosed with breast cancer, included patients who took any form of HRT.
"This study opens an entirely new direction for future research of breast cancers. When we learn how HRT favorably affects the biology of tumors we can then use that information in a therapeutic fashion to improve the outcome of women with breast cancer," said study co-investigator SuEllen Toth-Fejel, Ph.D., research assistant professor of surgery in the OHSU School of Medicine, who led the laboratory work on the project.