Endocrine Abstracts

Introduction: Parathyroid carcinoma (PC) occurs in 0.005% of all malignant tumors and in less than 1% in primary hyperparathyroidism (PHPT), but recent reports indicate increasing incidence of PC.

Aim: To estimate the prevalence of PC in Russia and to identify its distinctive characteristics relevant as preoperative markers.

Material and methods: We conducted a retrospective study based on the online Russian Registry of 3061 patients with PHPT. The analysis included patients with PC (n = 74), atypical adenomas (AA, n = 23) and adenomas (A, n = 1540). The demographic, clinical and laboratory features were compared between groups. Statistical analysis was performed with package Statistica 13 (StatSoft, USA) and SPSS (IBM, USA) and Bonferroni correction was used for multiple comparisons.

Results: PC was identified in 2,4% and AA in 0,8%. Most of the cases were reported in last 9 years of study (n = 52). Age of PHPT manifestation in the PC group was 53 year [43; 62], in AA 61.5 [43; 72] and A 56 [48; 62] (P = 0.0092). The ratio of men to women in PC was 1:4, AA 1:3.6, A 1:10 (P = 0,001). Levels of intact parathyroid hormone (iPTH, 15–65 pg/ml) were significantly higher in PC compared to AA and A (1024 [356; 1772] vs572 [3544; 1569] vs 174 [115; 305.5] respectively, P < 0, 001). Surprisingly the total calcium (Ca, 2.15–2.55 mmol/l) and ionized calcium levels (Ca+, 1.03–1.29 mmol/l) were higher in AA compared to PC and A: Ca 3.24 [3.01; 3.51] vs 3,18 [2.82; 3.6] vs 2.78 [2.63; 2.97], Ca+ 1.69 [1.59; 1.91] vs 1.55 [1.39; 1.69] vs 1.39 [1.29; 1.51], P <0.001). The most frequently localization of the PC was a right lower PG (32.4%). PC patients had more often bone fractures than AA and A (30% vs 22% vs 18% vs P < 0.001). However, AA patients compared to PC and A had a higher frequency of osteoporosis (65% vs 62% vs 45%, P <0.001), nephrolithiasis (52% vs 43% vs 0.4%) and GFR reduction (48% vs 28% vs 9%, P = 0.002). The prognostic significance for PC was excess of PTH more than 538 (sensitivity 80%, specificity 84%, AUC = 0.866) and Ca more than 2.97 (sensitivity 67%, specificity 75%, AUC = 0.713) according to ROC analysis. Recurrences of PC were reported in 16 cases (22%).

Conclusions: Our results demonstrate the increased incidence of PC in Russia. Malignant parathyroid tumors are associated with more severe clinical manifestations PHPT compared to A.