Abstract PD6-06: Oncologic outcome of pregnancy associated breast cancer: A case-control study (2017)

Abstract Introduction and Aims Pregnancy-associated breast cancer (PABC) is defined as the diagnosis of invasive breast cancer during the gestational period, within one year of pregnancy or any time during lactation. A diagnosis of PABC has traditionally been attributed a poor prognosis. The aim of this study was to assess the long-term outcome of patients diagnosed with PABC compared to a cohort of age-matched control patients. Methods A single-institution retrospective chart review was performed in 188 patients with PABC treated between the years of 1992 and 2015.Non-PABC controls were selected to match based on age and year of diagnosis. Clinicopathologic features, surgical and adjuvant treatments received, and clinical outcomes were assessed. Patients who were stage IV at diagnosis were excluded. Overall survival was estimated using Kaplan-Meier methods and compared between cases and controls using a log-rank test stratified on matched pair. Results Out of 188 patients with PABC, 63 (34%) were pregnant at the time of diagnosis and 125 diagnosed within 1 year of pregnancy (average: 6 months post partum). The characteristics of the PABC and case-matched controls are listed in Table 1 . Important pathological differences were evident with PABC patients compared to the non-PABC controls. PABC cases were more likely to be high grade (p&amp;lt;.001), node positive (p=.039) and less likely to be estrogen or progesterone receptor positive (p=.003). The majority of both cases and controls received chemotherapy (18% neoadjuvant). In the patients who were pregnant at time of diagnosis, 19 received chemotherapy during their pregnancy, with the most common combination being AC followed by paclitaxel in the post-partum period. Five year overall survival was similar for both groups, 88% for PABC patients and 95% for non-PABC case controls (p=.746) with a median follow up of 5.1 years. Table 1: Demographics, treatment, and outcome of PABC and non-PABC case-matched controlsPABC n=188Non PABC n=188p-valueDemographicsAge (mean)35.7yrs35.9yrs0.633BRCA1/2 carrier22%12%0.072SurgeryBreast Conservation22%38%0.001Immediate reconstruction post mastectomy81%84%0.544PathologyGrade 388%70%&amp;lt;0.001ER and/or PR positive56%72%0.003HER2 positive27%22%0.283Triple negative27%20%0.145Node positive27%47%0.039Clinical StageI-II67%79%0.010III33%21%Adjuvant treatmentsChemotherapy99%21%&amp;lt;0.001Neoadjuvant18%17%0.849Anthracycline84%81%0.393Taxane82%75%0.148Anti-HER220%15%0.238Anti-estrogen53%68%0.003Radiotherapy57%62%0.4005-year OS88%95%0.746Figures are reported as percentages for categorical variables. OS: Overall survival Conclusion Diagnostic and therapeutic advances have improved the oncological outcome for breast cancer patients, but not all of these have been adapted for pregnant patients. The consistent finding of higher-stage tumors in these patients reinforces the importance of utilizing developments in systemic treatments, potentially through case registries, to evaluate outcomes. PABC is associated with more adverse features than non-PABC controls matched for age and year of diagnosis. However, PABC is not in itself an adverse prognostic factor for survival after correcting for pathologic features. Citation Format: McCartan D, Kamer S, Eaton A, Seidman A, Murphy C, Gemignani M, Goldfarb S. Oncologic outcome of pregnancy associated breast cancer: A case-control study [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr PD6-06.