Predictive Factors for Diagnosis of Parathyroid Carcinoma in Primary Hyperparathyroidism

Abstract

Background: Parathyroid carcinoma (PC) is a rare endocrine cancer. Preoperative diagnosis is challenging because some of its clinical and biochemical features overlap with those of benign parathyroid disease; however, preoperative identification is important for appropriate surgical planning, as en bloc resection at the initial operation can improve patient outcomes. Objective: To identify preoperative factors associated with PC in patients with primary hyperparathyroidism and to evaluate their predictive capacity. Materials and Methods: A retrospective case-control study was conducted of patients with primary hyperparathyroidism who had undergone parathyroidectomy at Rajavithi Hospital between January 2008 and December 2023. Patients were divided into PC and benign groups based on pathological reports. Demographic, clinical, laboratory, and imaging data of the groups were compared. Binary logistic regression was used to identify the factors that predicted PC, and ROC curve analysis was performed to determine optimal cutoff values. Results: Of 102 patients, 12 (11.8%) had PC and 90 had benign disease. After multivariate analysis, palpable neck mass (adjusted OR 11.31, 95% CI 2.17 to 59.09, p=0.004) and serum calcium ≥13.35 mg/dL (adjusted OR 12.02, 95% CI 1.32 to 109.27, p=0.027) were independent predictors of PC. Serum calcium demonstrated good diagnostic performance (AUC 0.834), with a high negative predictive value (98.4%). Conclusion: A palpable neck mass and severe hypercalcemia are the key predictors of PC in primary hyperparathyroidism. These two simple factors can assist clinicians in PC diagnosis and surgical planning.