Hwangbo Y, et al. Endocrinol Metab. 2018 Jun;33(2):175-184. https://doi.org/10.3803/EnM.2018.33.2.175

Thyroid cancer is the most common cancer in Korea. Several susceptibility loci of differentiated thyroid cancer (DTC) were identified by previous genome-wide association studies (GWASs) in Europeans only. Here we conducted a GWAS and a replication study in Koreans using a total of 1,085 DTC cases and 8,884 controls, and validated these results using expression quantitative trait loci (eQTL) analysis and clinical phenotypes. The most robust associations were observed in the NRG1 gene (rs6996585, P=1.08 × 10⁻¹⁰) and this SNP was also associated with NRG1 expression in thyroid tissues. In addition, we confirmed three previously reported loci (FOXE1, NKX2-1 and DIRC3) and identified seven novel susceptibility loci (VAV3, PCNXL2, INSR, MRSB3, FHIT, SEPT11 and SLC24A6) associated with DTC. Furthermore, we identified specific variants of DTC that have different effects according to cancer type or ethnicity. Our findings provide deeper insight into the genetic contribution to thyroid cancer in different populations.

Hwangbo Y, et al. Endocrinol Metab. 2017 Mar;32(1):23-29. https://doi.org/10.3803/EnM.2017.32.1.23

Background: Several lines of evidence suggest that breast cancer (BC) and thyroid cancer (TC) occur together in the same female patients more frequently than would be expected by chance. This study investigated the prevalence and clinicopathological characteristics of second primary BC in TC patients and second primary TC in BC patients. Methods: A retrospective case-controlled study was performed in 4243 patients with differentiated TC and 6833 patients with BC. Age-matched control groups without second malignancies were selected. Results: Of the 4243 patients with TC, 55 patients developed subsequent BC during a five-year follow-up (range 2–40 years); the standardized incidence ratio (SIR) was 2.45 [confidence interval (CI) 1.83–2.96]. Among the 6833 patients with BC, 81 patients developed subsequent TC during a 6.2-year follow-up (range 2–40 years); the SIR was 2.18 [CI 1.43–2.82]. Subsequent second BC or TC diagnosed within five years of the initial primary malignancy showed more clinical characteristics consistent with early-stage cancer than did control BC or TC patients. Notably, the expression of both the estrogen and progesterone receptors was significantly higher in the tissues of BC patients with coexisting TC compared with those with BC alone. Conclusions: The overall risk of second primary TC or BC is increased in patients with prior BC or TC, respectively. The early detection of second cancer might have contributed to these findings. However, BC that coexisted with TC had a higher expression of hormone receptors, suggesting an association between the molecular pathogenesis of TC and BC.

Moon JH, et al. Endocrinol Metab. 2018 Jun;33(2):278-286. https://doi.org/10.3803/EnM.2018.33.2.278