Abstract P4-10-10: Assessment of short inter-pregnancy interval in breast cancer diagnosed during pregnancy

Abstract

Background: The relationship between pregnancy and breast cancer (BC) risk is not fully understood. Most of the literature has described this interaction in terms of the age at first pregnancy and the number of full-term pregnancies. During the prospective accrual of the “Joven & Fuerte” young women with BC program in Mexico, we identified patients with pregnancy-associated BC (PABC) that experienced a short inter-pregnancy interval (SIPI) (<18 months between a live birth and the beginning of a following pregnancy). To our knowledge, there are no descriptions of the interaction between SIPI and PABC. Objective: We aim to assess the occurrence of SIPI in patients with PABC, as well as describe their clinical features at presentation. Results: We included patients accrued in the “Joven & Fuerte” program from August 2014 and June 2018 at three Mexican cancer centers. A total of 375 patients ≤40 years-old with newly-diagnosed BC were assessed. 37 patients were diagnosed with PABC (10%), 21 during pregnancy and 16 after pregnancy. 6/37 (16%) patients with PABC experienced a SIPI, all diagnosed during pregnancy (28% of 21). The main clinicopathological features are described in the table 1. Table 1.Clinicopathological features of patients with PABC and SIPICaseAge at BC diagnosis (years)IPI (months)Pregnancy trimester at diagnosisStageBC subtype131183rdIIBNot available23262ndIIIAHR neg, HER2 pos337143rdIIAHR neg, HER2 pos436152ndIVHR pos, HER2 neg53142ndIIIAHR pos, HER2 neg63142ndIIICNot available Conclusion: According to the phenomena seen in this cohort of young BC patients, we hypothesize that SIPI may increase the incidence and/or modify the clinical outcomes of PABC. The evidence from clinical and laboratory data suggest that the mechanisms that could alter the interaction include, but are not limited to, the prolongation of the exposure to high concentrations of estrogens or their genotoxic metabolites, interaction with the effect of progesterone and other pregnancy-associated hormones on breast tissue, and immunologic factors. To date, to our knowledge there is no evidence about the effect of SIPI in PABC. Thus, research in this area should be encouraged, particularly in vulnerable women in limited-resource settings, where SIPI is, unfortunately, a common occurrence, and might represent a risk factor for BC/PABC. Citation Format: Diaz-Perez H, Del Toro-Mijares R, Lopez-Martinez EA, Muñoz-Lozano JF, Fonseca A, Platas A, Martinez-Cannon BA, Barragan-Carrillo R, Castro-Carrasco J, Limon-Gomez S, Villarreal-Garza C. Assessment of short inter-pregnancy interval in breast cancer diagnosed during pregnancy [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 P4-10-10.