MON-489 Comorbidity of Primary Hyperparathyroidism and Papillary Thyroid Cancer. A Single Center Outcomes

Abstract Introduction Concurrence of primary hyperparathyroidism in patients with thyroid disease has been previously reported by several studies. However, comorbidity between primary hyperparathyroidism (PHPT) and papillary thyroid cancer (PTC) has been sparsely described by previous, mostly case-series studies, and is considered rare. Since pathophysiological mechanisms behind the two diseases are supposed to be different, any link between these diseases has not been explained as yet. Hypothesis: Aim of the study was to investigate the possible concurrence for the two diseases in people who underwent thyroidectomy for suspected thyroid nodules. Methodology Retrospective observational study that included 2913 patients (24% men with mean age 49.82 yrs, 76% women mean aged 47.73 yrs), who underwent total thyroidectomy during the last 13 years (2005-2018) at the Department of Endocrine Surgery, Euroclinic Hospital, in Greece. The patient-groups were categorised according to histopathology criteria of the thyroid and/ or parathyroid glands (in case of comorbidity of primary hyperparathyroidism (PHPT) diagnosed prior to surgery). Results: Statistical analysis revealed benign histopathology findings in 1945 patients (64%), while papillary cancer was found in 978 (32%). Among patients with non-malignancy, 16 (11 women/5 men) had PHPT, but in those with papillary cancer, PHPT was diagnosed in 38 (33 women/5 men) individuals. The relative risk for the concurrence of PHPT and PTC was 2.033 (95%CI 1.69 to 2.43, P<0.0001). Age groups between 30 and 60 yrs were associated with the highest relative frequency of comorbidity (82%). A significant positive correlation was observed between less aggressive PTC histopathology findings and PHPT concurrence (P<0.0001). Interestingly, no patient with PTC and PHPT had either capsular invasion or regional/distant metastases. Moreover, most patients with comorbidity (92%) had a tumour diameter smaller (mean 6.3 mm) than those with PTC alone (mean 18 mm). Conclusions: Our study found that the comorbidity between primary hyperparathyroidism and PTC may be considered as possible. Endocrinologist’s diagnostic approach may add serum calcium and parathormone levels in patients who undergo evaluation for suspected thyroid nodules. Patients with PHPT and PTC had mostly microcarcinomas, and histopathology findings showed a less aggressive PTC pattern. Further large cohorts as well as genetic studies, are needed to duplicate our results and further highlight possible common pathogenetic pathways behind PHPT and PTC concurrence.