Background: Parathyroid cancer is rare and often fatal. This review provides an in-depth analysis of 330 clinical cases reported in detail. These data are used to inform a proposal for a hitherto lacking TNM staging system.
Materials and methods: All case reports or series with sufficient case details of parathyroid cancer were identified from PubMed, and data were analyzed using SPSS.
Results: Of 330 patients, 117 (35%) died of disease and 207 (63%) experienced recurrence in a total of 2007 follow-up years and a mean length of follow-up of 6.1 years. Histopathology findings rather than biochemical or clinical features predict outcome. In univariate analysis, survival and recurrence rates are significantly influenced by gender (male relative risk [RR] 1.7, 95% confidence interval [95% CI] 1.0-2.7, P < .01), and presence of vascular invasion (RR 4.3, 95% CI 1.1-17.7, P < .01), or lymph node metastases (RR 6.2, 95 %CI 0.9-42.9, P < .001). Failure to perform oncological surgery carries a high risk for recurrence and death (local versus en bloc resection RR 2.0, CI 1.2-3.2, P < .01) as for redo surgery. Staging by a novel anatomy-based TNM system identifies significant outcome variation as to recurrence and death. Separation of patients into low and high risk identifies a 3.5-7.0 fold higher risk of recurrence and death (P < .01) for the high-risk group. Distant metastases predominantly target mediastinum and lung.
Conclusion: Understaging and undertreatment are shown to contribute to high recurrence rates and death toll. To improve outcome, en bloc resection including central lymph node dissection should be the minimal surgical approach in any patient with suspected parathyroid cancer.