Abstract OT1-04-02: POSITIVE: A study evaluating pregnancy, disease outcome and safety of interrupting endocrine therapy for premenopausal women with endocrine responsive breast cancer who desire pregnancy (IBCSG 48-14/big 8-13)

Abstract

Abstract Background: Young patients with breast cancer (BC) are often diagnosed before completing their families. The best available retrospective evidence suggests that pregnancy after BC does not negatively impact disease outcomes overall and in patients with endocrine responsive disease, and is safe for the offspring. However, given also the possibility of extended adjuvant endocrine therapy (ET) (5-10 years), it is not feasible for many of these women to delay pregnancy until completion of therapy. Prospectively evaluating the safety of temporary interruption of ET to allow conception is an unmet, patient-oriented, medical need. Trial Design: Young patients with endocrine responsive early BC who desire pregnancy will interrupt ET for up to 2 yrs to attempt child-bearing. As resumption of menses and conception depends on many factors (e.g. patient’s age and adjuvant treatment received), the 2-yr interruption period is approximate, intended to include treatment wash-out (3 mos), conception (~3-6 mos), delivery (~9 mos), and breast feeding (~6 mos). Patients will be strongly advised to resume ET as soon as pregnancy attempts/deliveries are concluded, and to complete the planned 5-10 yrs of ET. Major Eligibility Criteria - Histologically-proven stage I-III endocrine-responsive BC. - Patient’s wish to become pregnant. - Age ≥ 18 and ≤ 42 years at enrollment. - Adjuvant ET (selective estrogen receptor modulator [SERM] alone, GnRH analogue plus SERM or aromatase inhibitor) for ≥18 months but ≤30 months, stopped within 1 month prior to enrollment. - Premenopausal status at BC diagnosis. Specific Aims 1. To assess the risk of BC relapse associated with temporary interruption of ET to permit pregnancy. 2. To evaluate pregnancy success rate and offspring outcome. Statistical Methods: With 500 pts enrolled and followed for a median of 3 years, the statistical design is based on the 95% CI for the 3-year BC recurrence rate. Interim monitoring assumes a 2% BC recurrence risk/yr with continuous ET and a recommendation to stop the study early if the BC risk exceeds 4%/yr with ET interruption. Translational Research will evaluate fertility, pregnancy and BC biology determinants (e.g. ovarian function, uterine evaluation and circulating tumor DNA). Fresh frozen paraffin embedded tissue of the primary tumour will be collected to evaluate parameters related to the biology of BC in young women. All material will be banked centrally. Psycho-oncological Companion Study (POCS) will evaluate fertility concerns, psychological well-being and decisional conflict. It is mandatory in North America and open to interested centers elsewhere. Accrual: Target: 500; Actual: 421 (30 June 2019) Psycho-oncological Companion Study Accrual: Target: ~200; Actual: 196 (30 June 2019) Contact Information: POSITIVE is conducted and sponsored by the International Breast Cancer Study Group. The Alliance for Clinical Trials in Oncology is the US sponsor for NCTN. Contact Monica Ruggeri, IBCSG Coordinating Center, monica.ruggeri@ibcsg.org, or Trial Coordinators at ibcsg48_positive@fstrf.org. Citation Format: Olivia Pagani, Ann H Partridge, Fedro A Peccatori, Hatem A Azim, Chikako Shimizu, Cristina Saura, Ellen Warner, Anna B Sætersdal, Judith R Kroep, Monica Ruggeri, Richard D Gelber. POSITIVE: A study evaluating pregnancy, disease outcome and safety of interrupting endocrine therapy for premenopausal women with endocrine responsive breast cancer who desire pregnancy (IBCSG 48-14/big 8-13) [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr OT1-04-02.