125P Suboptimal ovarian suppression during adjuvant endocrine therapy for premenopausal women with breast cancer: An exploratory analysis of the PREFER and GIM 23 studies

• DOI: 10.1016/j.esmoop.2024.103113
• Publication Date: 2024-05-17T11:19:19Z
• Authors: S. Nardin; L. Del Mastro; I. Giannubilo; T. Ruelle; M.G. Razeti; L. Arecco; R. Borea; D. Favero; M. Perachino; E. Chiappe; C. Lanzavecchia; L. Barcellini; L.M. Tomasello; C. Molinelli; E. Blondeaux; M.M. Latocca; M. Lambertini; F. Poggio
• Keywords: Adjuvant Therapy; Exploratory analysis

Adjuvant endocrine therapy (ET) with exemestane combined LHRH analog (LHRHa) is standard of care for premenopausal women hormone receptor-positive breast cancer. However, LHRHa may not always achieve complete ovarian suppression in these patients. The PREFER-Fertility (NCT02895165) and GIM 23-POSTER (NCT05730647) are prospective, observational studies that enrolled eligible to receive (neo)adjuvant chemotherapy and/or ET. We conducted an exploratory analysis patients achieving suboptimal function at the coordinating center both studies, defined as estradiol levels greater than 25.1 ng/L or resumption menstruation least 3 months after start exemestate plus LHRHa. As February 2024, a total 1616 were (766 PREFER 850 23), whom 528 included from main center. Among them, 26 (4.9%) had suppression. Median age was 39 (interquartile range (IQR) 36-46). body mass index 21.8 kg/m2 (84.6% <25). Main histopathological characteristics summarised table. 65.4% received chemotherapy, mainly anthracycline taxane (93.8%), adjuvant abemaciclib. time last 7 months, 17 already on during chemotherapy. Monthly leuprorelin given 65% cases, while others monthly triptorelin. (IQR: 5-20). At median follow-up 5 years 2-6), relapse disease.Table: 125PCharacteristicsN (%)TNM - StageIA14 (53.9)IB3 (11.5)IIA5 (19.2)IIB2 (7.7)IIIA2 (7.7)Grading11 (3.8)218 (69.3)35 (19.2)NA2 (7.7)HistologyDuctal21 (80.8)Lobular1 (3.8)Other4 (15.4)Ki67<2012 (46.2)≥2014 (53.8)HER2 status012 (46.1)1+5 (19.2)2+2 (7.7)2+ FISH amplified 3+7 (27) Open table new tab In our cohort, almost 5% did Oncologists should be aware serial monitoring performed address this.