Similarity of uterine mucosa changes in patients treated by Raloxifen and Tamoxifen

Background: Selective estrogen receptor modulators (SERMS) like Tamoxifen and Raloxifen are used for menopausal symptoms, prevention of cardio-vascular diseases, osteoporosis and mammary carcinoma. Tamoxifen acts as an estrogen inhibitor on the mammary gland, but stimulates postmenopausal uterine mucosa in about 25% of cases while decreasing the risk of osteoporosis. Materials, Methods and Results: In three menopausal women, 56, 79 and 62 years of age, we found uterine mucosal changes similar to what is found in Tamoxifen-treated patients. Using light microscopy and immuno-histopathological techniques, partly cystic mucosa with both atrophic and proliferating glands was found. Strong stromal proliferation was also seen with the typical sharp-edged form of stromal cells and mitoses. A strong ostrogen and progesterone reaction was revealed with immuno-histopathological techniques in both gland and stromal parts. Conclusion: Taking into account the variable amount of different estrogen-receptor types in the uterine mucosa, we can not in the long run expect that no patient will react with estrogen-stimulation features on SERMs like Raloxifen. Further studies and thorough observations are needed to elucidate the true frequency of Raloxifen impact on the uterine mucosa.