Abstract GS02-13: Pregnancy after breast cancer in young women with germline BRCA pathogenic variants: results from an international cohort study

Abstract Background: Oncofertility counseling in BRCA carriers has unique challenges due to a possible negative impact of germline pathogenic/likely pathogenic variants (PVs) on reproductive potential and the indication to undergo risk-reducing bilateral salpingo-oophorectomy. While previous studies demonstrated the safety of pregnancy in women with prior breast cancer (BC) history, limited evidence exists in BRCA carriers specifically. We report the results of the largest study to date investigating likelihood of pregnancy after BC, reproductive and disease outcomes specifically in BRCA carriers. Methods: This was an international, multicenter, hospital-based, retrospective cohort study including young BRCA carriers with history of BC (NCT03673306). Eligible patients were women harboring germline PVs in BRCA1 and/or BRCA2 and diagnosed with stage I-III invasive BC at the age of ≤ 40 years between January 2000 and December 2020. BRCA healthy carriers or patients with BRCA variants of unknown significance, non-invasive BC, lack of follow-up, prior ovarian cancer or other malignancies without history of BC were excluded. Primary endpoints were pregnancy rate and disease-free survival (DFS). Overall survival (OS), BC specific survival (BCSS), pregnancy, fetal and obstetric outcomes were secondary endpoints. To mitigate the impact of guaranteed time bias, two survival analyses were performed: 1) Extended Cox model with occurrence of pregnancy as a time-varying covariate; 2) Case-control analysis by matching 1:3 patients with and without a pregnancy for type of BRCA PV, hormone receptor status, nodal status and year at diagnosis; moreover, each control had to have a disease-free interval longer than the time occurring between BC diagnosis and conception of the matched case. Results: From 78 centers worldwide, 4,732 patients were included, of whom 659 had at least one pregnancy after BC (pregnancy cohort) and 4,073 did not (non-pregnancy cohort). Patients in the pregnancy cohort were significantly more likely to carry BRCA1 PVs, to be younger at BC diagnosis, to have node-negative and hormone receptor-negative (HR-) BC (all p< 0.01). Pregnancy rate at 10 years was 22% (95% CI 21%-24%) overall, 18% (95% CI 16%-21%) and 26% (95% CI 24%-26%) in patients with HR+ and HR- BC, respectively (p< 0.01). Median time from BC diagnosis to conception was 3.5 years (IQR 2.2-5.3 years), significantly longer in patients with HR+ than HR- BC (4.3 vs 3.2 years, p< 0.01). Among 659 patients with a pregnancy after BC, 45 (6.8%) and 63 (9.6%) experienced an induced abortion or a miscarriage, respectively. Of the 517 (78.5%) patients with completed pregnancy, 54 (10.4%) had twins and 406 (78.5%) delivered at term (delivery ≥37 weeks). Among the 571 babies born, 5 (0.9%) had congenital anomalies. Median follow-up was 7.8 years (IQR, 4.5-12.6 years). No significant difference in DFS was observed between the pregnancy and non-pregnancy cohorts (unadjusted HR 0.97, 95% CI 0.82-1.15, p=0.74; adjusted HR [aHR] 0.99, 95% CI 0.81-1.20, p=0.90). Patients in the pregnancy cohort showed significantly better BCSS (HR 0.53, 95% CI 0.38-0.74, p< 0.01; aHR 0.59, 95% CI 0.41-0.86, p< 0.01) and OS (HR 0.52, 95% CI 0.38-0.72, p< 0.01; aHR 0.58, 95% CI 0.40-0.85, p< 0.01). Similar results were obtained in the case-control analysis. Subgroup analyses of survival endpoints according to patient, tumor and treatment characteristics will be presented at the conference. Conclusions: In this global study, 1 out of 5 young BRCA carriers conceived within 10 years after a BC diagnosis, higher than rates previously reported in unselected young BC populations. Pregnancy following BC in BRCA carriers did not appear to adversely impact maternal prognosis or fetal outcomes. These findings should be incorporated into oncofertility counseling of young BRCA carriers with BC. Citation Format: Matteo Lambertini, Eva Blondeaux, Elisa Agostinetto, Anne-Sophie Hamy-Petit, Hee Jeong Kim, Camila Chiodi, Rinat Bernstein-Molho, Florentine Hilbers, Katarzyna Pogoda, Estela Carrasco Lopez, Kevin Punie, Jyoti Bajpai, Michail Ignatiadis, Halle Moore, Kelly-Anne Phillips, Angela Toss, Christine Rousset-Jablonski, Fedro Alessandro Peccatori, Tiphaine Renaud, Alberta Ferrari, Shani Paluch-Shimon, Robert Fruscio, Wanda Cui, Stephanie Wong, Claudio Vernieri, Kathryn Ruddy, Maria Vittoria Dieci, Alexios Matikas, Mariya Rozenblit, Cynthia Villareal Garza, Laura De Marchis, Lucia Del Mastro, Fabio Puglisi, Maria Del Pilar Estevez-Diz, Kenny A. Rodriguez-Wallberg, Bela Mrinakova, Sarah Meister, Luca Livraghi, Florian Clatot, Rinat Yerushalmi, Carmine De Angelis, Rodrigo Sánchez-Bayona, Icro Meattini, Natalia Cichowska-Cwalińska, Martine Berlière, Mahmoud Salama, Ugo De Giorgi, Amir Sonnenblick, Hatem Azim, Ann Partridge. Pregnancy after breast cancer in young women with germline BRCA pathogenic variants: results from an international cohort study [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr GS02-13.

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