Detecting breast cancer with mammography and biopsy is more difficult in women who use estrogen and progestin hormone therapy, according to an analysis of data from the Women's Health Initiative (WHI) trial. by Anthony J. Brown, MD

Detecting breast cancer with mammography and biopsy is more difficult in women who use estrogen and progestin hormone therapy, according to an analysis of data from the Women's Health Initiative (WHI) trial.

Doctors "should be aware that breast cancer diagnosis is more difficult in women using combined hormone therapy," lead researcher Dr. Rowan T. Chlebowski told Reuters Health. Such therapy has a considerable effect on the risks of having an otherwise avoidable mammogram or breast biopsy, he added.

Other studies have examined the impact of hormone replacement therapy on breast cancer detection, noted Chlebowski, a researcher with the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center in Torrance, California. However, unlike the current study, these studies generally did not examine how hormone therapy affects breast cancer detection over the course of treatment, he explained.

Because of this difference in study design, "we can provide, for the first time, precise...estimates of what a woman can expect if she uses estrogen plus progestin for about five years."

As reported in the Archives of Internal Medicine, the researchers analyzed data from 16,608 postmenopausal women who were randomly assigned to receive estrogen plus progestin or an inactive placebo as part of the WHI trial.

Mammography and breast examinations were performed at the start of the study and annually, and breast biopsies were performed according to the findings of these exams. The impact of hormone therapy on breast cancer detection was determined through 5.6 years of treatment.

Overall, 35 per cent of mammograms in hormone users were considered abnormal compared with just 23 per cent of those in placebo users. Most importantly, the mammograms performed in hormone users were less able to visualize breast cancer and resulted in more unnecessary biopsies.

Stopping hormone therapy improved breast cancer detection with mammography and breast biopsy, but the diagnostic ability was still inferior compared with that in women who had never used estrogen and progestin. The reduced ability to detect cancer persisted for at least 12 months after hormone therapy stopped.

Doctors should make their patients on combined hormone therapy aware that the risk of having an unnecessary mammogram or breast biopsy is 'considerable,' about ten and four per cent, respectively, over five years, Chlebowski noted.


Source: Reuters