Improved prediction of calcitonin normalization in medullary thyroid carcinoma patients by quantitative lymph node analysis

BACKGROUND. The aim of this study was to identify better prognostic parameters for normalization of serum calcitonin in medullary thyroid carcinoma (MTC) patients. METHODS. In 73 patients who had undergone systematic lymph node dissection for MTC between September 1995 and November 1998, preoperative (n = 29) and postoperative (n = 65) basal and stimulated serum calcitonin were correlated with the pTNM classification and the number of positive regional lymph nodes and compartments. RESULTS, In contrast to pT and M, there was a significant correlation between postoperative calcitonin and the pN category. With rising numbers of positive lymph nodes (0, 1-9, 10-19, and greater than or equal to 20), postoperative basal and stimulated calcitonin increased exponentially, and gross distant metastases (M1) occurred more frequently (0%, 4%, 13%, and 50%; P = 0.013). Conversely, serum calcitonin was less often normalized (65%, 31%, 0%, and 0%; P = 0.003). There was a close correlation between the number of positive lymph nodes and the number of affected compartments (P < 0.001; r = 0.93). Irrespective of location, involvement of 10 or more lymph nodes and more than 2 compartments precluded normalization of serum calcitonin. CONCLUSIONS. Quantitative lymph node analysis of MTC improves prediction of calcitonin normalization. When more than two compartments are involved, normalization of serum calcitonin cannot be attained. Surgery should then be less extensive and more directed at preventing local complications. Cancer 2000;88: 1909-15, (C) 2000 American Cancer Society.