Prospective study on gynaecological effects of two antioestrogens tamoxifen and toremifene in postmenopausal women

Abstract

To assess and compare the gynaecological consequences of the use of 2 antioestrogens we examined 167 postmenopausal breast cancer patients before and during the use of either tamoxifen (20 mg/day, n = 84) or toremifene (40 mg/day, n = 83) as an adjuvant treatment of stage II–III breast cancer. Detailed interview concerning menopausal symptoms, pelvic examination including transvaginal sonography (TVS) and collection of endometrial sample were performed at baseline and at 6, 12, 24 and 36 months of treatment. In a subgroup of 30 women (15 using tamoxifen and 15 toremifene) pulsatility index (PI) in an uterine artery was measured before and at 6 and 12 months of treatment. The mean (±SD) follow-up time was 2.3 ± 0.8 years. 35% of the patients complained of vasomotor symptoms before the start of the trial. This rate increased to 60.0% during the first year of the trial, being similar among patients using tamoxifen (57.1%) and toremifene (62.7%). Vaginal dryness, which was present in 6.0% at baseline, increased during the use of tamoxifen (26.2%) and toremifene (24.1%). Endometrial thickness increased from baseline (3.9 ± 2.7 mm) to 6.8 ± 4.2 mm at 6 months ( P < 0.001), and no difference emerged between the 2 regimens in this regard. Before the start of the antioestrogen regimen, the endometrium was atrophic in 71 (75.5%) and proliferative in 19 of 94 (20.2%) samples; 4 patients had benign endometrial polyps. During the use of antioestrogen altogether 339 endometrial samples were taken (159 in tamoxifen group, 180 in toremifene group). The endometrium was proliferative more often in the tamoxifen group (47.8%) than in the toremifene group (32.2%) ( P < 0.0001). 20 patients had a total of 24 polyps (17 in tamoxifen and 9 in toremifene group, P < 0.05) during the use of antioestrogens. One patient in the toremifene group developed endometrial adenocarcinoma at 12 months, and one patient had breast cancer metastasis on the endometrium. Tamoxifen failed to affect the PI in the uterine artery, but toremifene reduced it by 15.0% ( P < 0.05) by 12 months. In conclusion, tamoxifen and toremifene cause similarly vasomotor and vaginal symptoms. Neither regimen led to the development of premalignant endometrial changes. Our data suggest that so close endometrial surveillance as used in our study may not be mandatory during the first 3 years of use of antioestrogen treatment. © 2001 Cancer Research Campaign http://www.bjcancer.com

Toremifene in the treatment of breast cancer

“…A 3-year study specifically designed to compare the gynecological effects of toremifene 40 mg and tamoxifen 20 mg in 167 postmenopausal breast cancer patients showed that the incidence of proliferative endometrium was increased to a significantly (P < 0.0001) lesser extent by toremifene (from 20.0% to 32.2%) than by tamoxifen (from 20.4% to 46.8%) [60] .…”

Pure oestrogen antagonists for the treatment of advanced breast cancer

“…Disappointing efficacy data for both droloxifene and idoxifene when compared with tamoxifen or when used in tamoxifen-resistant disease have led to their development being halted. Toremifene (chloro-tamoxifen), which has similar efficacy but fewer agonist properties compared with tamoxifen (Marttunen et al 1998(Marttunen et al , 2001, remains in clinical development in the breast cancer prevention setting.…”

Endometrial mullerian adenosarcoma after toremifene treatment in breast cancer patients: a case report

“…MB Marttunen et al suggested that at least in the first 2-3 years, toremifene treatment does not increase the risk of endometrial cancer. 12 According to Ha et al, 8 the majority of uterine cancers developed after more than 1 year of treatment, and the annual hazard rate for endometrial cancer was 1.0 per 1,000 patient treatment years. Adenosarcoma is a very rare uterine malignancy detected in this patient on toremifene therapy who has no risk factors for uterine malignancy other than old age.…”