The relationship between proliferation activity and parathyroid hormone levels in parathyroid tumors

Purpose: This article examines as to whether the Ki-67 index may be useful as a marker for cell proliferation, as well as to whether Ki-67 immunohistochemical expression and parathyroid hormone (PTH) levels are useful in distinguishing between parathyroid carcinoma (PC) and adenoma. Methods: A retrospective analysis of 50 patients (10 with PC and 40 with adenoma) who had been previously diagnosed with primary hyperparathyroidism (PHPT) was conducted. Normal parathyroid glands served as the control group. Immunostaining of Ki-67 was estimated through image analysis and the results were statistically analyzed. Results: Ki-67 was higher in PC patients (median 785.15) compared to adenoma patients (median 297.41; Mann-Whitney U-test p<0.001). ROC analysis confirmed that Ki-67 has a positive predictive marker in diagnosing cancer. Mann-Whitney U-test confirmed a highly statistically significant difference in the preoperative PTH levels between the PC and adenoma group (p <0.001). The PTH serum preoperative level was higher in PC patients (median 1721) than in those with adenoma (median 189.5). A highly significant correlation was also found between Ki-67 and preoperative PTH levels (p <0.001). Conclusion: A higher rate of cellular proliferation was noted in malignant tumors as compared to benign tumors. Moreover, the expression profile of Ki-67 and high PTH levels in this study indicates a role for them as potential markers of malignancy.