7079 Analysis of the Association Between Recent Exposure to Pregnancy and the Histological Subtype of Thyroid Cancer

Abstract Disclosure: T.L. Danehy: None. A. Manavalan: None. C. Schechter: None. Y. Tomer: None. Objective: Thyroid cancer is the second most common cancer diagnosed in pregnancy (1). Both HCG and estrogen have been implicated in this increased risk (2). While the classic variant of papillary thyroid cancer is the most common subtype in non-pregnant women, the effect of exposure to pregnancy on histological subtype remains unclear and could have clinical implications. Methods: This is a retrospective cohort study conducted at Montefiore Medical Center. All women of childbearing age (18-45) with a diagnosis of thyroid cancer between the years of 2015 -2020 (n=152) were identified. 43 participants were excluded due to missing data. The remaining 114 participants were divided into 2 groups; Group 1 or the exposed (n=25) included those diagnosed with thyroid cancer during pregnancy or in the 2 years postpartum and had carried their pregnancy to term, and Group 2 or the unexposed (n =89) included those who were nulliparous or diagnosed with thyroid cancer prior to pregnancy or more than 2 years post-partum. Charts were reviewed to obtain data on the initial histopathology and were classified into Follicular Thyroid Cancer (FTC), Hurthle cell carcinoma (HCC), Medullary Thyroid Cancer (MTC), and Papillary Thyroid Cancer (PTC). Results: Women in the unexposed group were significantly younger than those exposed to pregnancy (28.7 vs 32.7 p=0.005). The distribution of histological types in the two groups was as follows:Group 1: FTC (13.0%), HCC (0%), MTC (0%), and PTC (87%). Group 2: FTC (5.7%), HCC (2.3%), MTC (3.4%), PTC (88.5%). Thus, the incidence of follicular thyroid cancer in the exposed group was > 2-fold that observed in unexposed group, but this difference did not meet statistical significance (p=0.594). Conclusions: Our study showed a non-statistically significant increased incidence of FTC in women who were diagnosed with thyroid cancer during pregnancy or 2 years postpartum compared to unexposed women. While this did not meet statistical significance, our study sample was small and may have been underpowered. Therefore, our findings merit further investigation given their potential clinical implications. References: 1. Smith L.H., Danielsen B., Allen M.E., Cress R. Cancer associated with obstetric delivery: results of linkage with the California cancer registry. Am J Obstet Gynecol. 2003 2. Tafani M., De Santis E., Coppola L., Perrone G.A., Carnevale I., Russo A. Bridging hypoxia, inflammation, and estrogen receptors in thyroid cancer progression. Biomed Pharmacother. 2014;68(1):1-5 Presentation: 6/2/2024