Abstract P1-17-02: Outcomes and safety of paclitaxel and granulocyte-colony stimulating factor (GCSF) in breast cancer in pregnancy (BCP) - A multi-institutional retrospective analysis

Abstract

Abstract Background BCP is uncommon; however, the frequency is increasing due to trends in delayed childbearing. Studies have suggested that some systemic therapies, including doxorubicin and cyclophosphamide, can be delivered safely during pregnancy after the first trimester, whereas agents such as trastuzumab and endocrine therapy are contraindicated due to risk to the fetus. Data remain limited on the efficacy and safety of administering taxane chemotherapy or growth factor support during pregnancy. We retrospectively evaluated the safety of systemic therapies, including paclitaxel and GCSF, as well as clinical outcomes, in a multi-institutional cohort of patients (pts) with BCP. Methods Pts treated for BCP from 1996-2018 from 3 large academic institutions were included. Demographic, oncologic treatment, and obstetric/neonatal outcomes data were obtained from medical records. Disease-free survival (DFS) and overall survival (OS) were estimated by Kaplan-Meier; Log-rank test were used to compare different groups/outcomes. Associations were calculated by Fisher's exact test. Results A total of 114 pts diagnosed with BCP were included. The median age was 35 years (range 25-44) and median gestational age at diagnosis was 18 weeks (range 2-38). BCP was predominantly early stage at diagnosis (stage I 28.0%, stage II 53.5%) and ER+/HER2- negative (48.2%). Sixty-three (55.2%) women received chemotherapy, 13 (11.4%) received paclitaxel and 11 (9.6%) GCSF (daily or depot injections) while pregnant. A total of 78% of pts with HER-2-positive BCP (28/36) received trastuzumab after delivery (11% were treated before 2005 and 5.5% were T1a). With median follow-up of 67.7 months, median DFS (stage I-III) was 212.8 months (CI 95% 108.4-317.1), and median OS (stage I-IV) was not reached. Subgroup analysis suggested a higher DFS for pts diagnosed in the 1sttrimester compared to the 3rdtrimester among women with stage II-III (HR 0.25 CI 95% 0.09-0.70, p= 0.03). Among women who received paclitaxel, there was no significant increase in adverse obstetrical/neonatal outcomes: preterm delivery (23.1% vs 13.1%, p 0.39), low weight newborn (7.7% vs 9.1 %, p 1.0), congenital malformations (0% vs 6.1%, p 1.0) or acute neonatal adverse outcomes (7.7% vs 4.0%, p 0.51), which include NICU need and Apgar 5'<7, compared to pts who did not receive paclitaxel. Among pts who received GCSF during pregnancy, adverse outcomes were numerically but not statistically higher than women who did not receive growth factor: preterm delivery (36.3% vs 11.0%, p 0.051), low weight newborn (27.3% vs 6.9%, p 0.058), congenital malformations (9.1% vs 1.0%, p 0.18) or acute neonatal adverse outcomes (18.2% vs 3.0%, p 0.07). Conclusion In this multi-institution cohort of BCP pts, despite a small number of pts, exposure to contemporary therapies including paclitaxel was not associated with unfavorable obstetrical/neonatal outcomes and these results suggest it is safe to administer during pregnancy under the care of a multidisciplinary team. Although not statistically significant, GCSF presented numerical worse outcomes and combining data from several cohorts would be helpful to provide confirmation of these findings. Citation Format: Exman P, Freret TS, Economy KE, Chen WY, Parsons HA, Lin NU, Moy B, Tung NM, Partridge AH, Mayer EL. Outcomes and safety of paclitaxel and granulocyte-colony stimulating factor (GCSF) in breast cancer in pregnancy (BCP) - A multi-institutional retrospective analysis [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-17-02.