A new analysis of the WHI breast cancer data examined the impact of estrogen alone on breast cancer detection. For this analysis, the breast cancer researchers examined the effects of estrogen alone on mammogram performance and breast biopsy results. The study investigators reported that after an average follow-up of 7 years
Women treated with estrogen alone had fewer invasive breast cancers than women receiving no estrogen, though the difference was not statistically significant.
The percent of mammograms that required a short follow-up exam was higher in the estrogen group (39%) than in the control group (30%).
The percent of abnormal mammograms was not different between the control group and the estrogen group.
Treatment with estrogen alone resulted in more breast biopsies being taken compared to women receiving no hormone therapy; however, the percent of biopsies diagnosed as cancer was lower in women receiving estrogen.
Overall, these are very positive results for estrogen-alone hormone therapy. While hormone therapy with estrogen alone resulted in more women getting mammogram results that required short-term follow-up and in more biopsies, the resulting mammograms and biopsies did not indicate cancer any more than was observed in untreated postmenopausal women. Despite these positive finding that estrogen alone therapy does not appear to negatively impact breast cancer detection, it is important to remember that estrogen alone therapy is considered only suitable for women without a uterus. Furthermore, the WHI study did report an increased risk for stroke and leg blood clots with estrogen alone therapy. Therefore, it is vital that women considering estrogen alone hormone therapy to discuss their overall health risk profile with their physician.