Postmenopausal hormone therapy and the risk of breast cancer: a contrary thought

Breast tumor characteristics in hormone replacement therapy users

The aim of this study was to further elucidate the influence of HRT use, regarding duration, regimen and route of administration, on breast tumor characteristics. We evaluated the associations between HRT use and breast tumor characteristics in 530 postmenopausal women diagnosed with invasive breast cancer. Detailed information on HRT use and mammographic attendance were collected through a postal questionnaire. Adjusted odds ratios and 95% confidence intervals were calculated using logistic regression. Tumors in HRT users were significantly smaller, more often of ductal histologic type and with lower grade and lower mitotic index compared to tumors in nonusers. Tumor characteristics did not vary significantly by HRT duration, regimen and route of administration, except for mitotic index, which was more often of score 2 in long-term users, and of score 3 in short-term users. Higher mammographic surveillance among HRT users did not explain our results. We conclude that tumors in HRT users have a more favorable prognostic profile regardless of duration, regimen and route of administration. These effects seem to be due to the influence of HRT on preexisting tumors causing their greater differentiation rather than earlier detection due to mammographic surveillance.

Hormone replacement therapy (HRT), breast cancer and tumor pathology

Within an average observation period of 5-6 years, several clinical trials reported an increased risk of breast cancer due to hormone replacement therapy (HRT). However, it remains disputable, whether the increased rate of breast cancers detected within the given time frame is indeed due to newly induced tumors and thus constitutes HRT-initiated primary breast cancers. Onco-pathologically speaking it appears more likely that HRT stimulates the growth of already existing small tumor nests which - due to their small size - would otherwise go undiagnosed. The major arguments are: In summary, HRT is hence more likely to be a tumor promoter than a de novo-inducer of breast cancers.