Parathyroid Cancer: Comparison with Benign Hyperparathyroidism

Purpose: The preoperative diagnosis of parathyroid cancer (PC) is challenging. The purpose of this study was to identify the differences between PC and benign primary hyperparathyroidism. Methods: The medical records of 85 hyperparathyroidism patients that underwent surgery between 2001 and 2017 were retrospectively reviewed. Results: Seven of the 85 were diagnosed with PC. Mean age was 53.0±13.0 years and 66 (77.6%) were women. Follow-up duration was 52.9±44.4 months. Tumors were larger (3.50±1.26 cm vs. 2.10±0.84 cm, P=0.002), and intact parathyroid hormone (iPTH) (1,142.8±524.5 pg/mL vs. 461.2±513.5 pg/mL, P=0.002) and alkaline phosphatase (ALP) (398.6±493.6 U/L vs. 166.7±181.1 U/L, P=0.01) levels were higher in cancer patients than in benign primary hyperparathyroidism. Intraoperatively, adhesion to surrounding soft tissue or the thyroid gland was detected more frequently in cancer (85.7% vs. 12.8%, P<0.001). Two patients experienced recurrences and one of them died from PC. Conclusion: PC patients had larger tumors size, and higher serum iPTH and ALP levels. Intraoperative detection of adhesion to surrounding soft tissue/thyroid importantly raised suspicion of PC. Surgeons operating for hyperparathyroidism should be prepared to perform an appropriate en bloc resection initially upon suspicion of PC.