Biochemical Cure after Reoperations for Medullary Thyroid Carcinoma: A Meta-analysis

Despite meticulous surgical techniques, calcitonin levels remain detectable in 40 % to 66 % of patients after initial surgery for medullary thyroid carcinoma (MTC), and the optimal surgical management for persistent or recurrent disease remains controversial. Previous studies suggest that biochemical cure, defined by normalization of postoperative calcitonin measurements, predicts disease-free survival. Reoperative approaches range from targeted removal of detectable disease to comprehensive compartment-oriented lymph node clearance. A proportional meta-analysis of clinical case series of postoperative calcitonin clearance after reoperation for MTC was performed. Studies were obtained from PubMed, Embase, Scopus, and the Cochrane Library. Twenty-seven articles capturing data of 984 patients met the inclusion criteria for the meta-analysis. Overall, normalization of calcitonin after reoperation for MTC occurred in 16.2 % of patients [95 % confidence interval (CI) 14.0-18.5]. Stratified by operative procedure, targeted selective lymph node removal procedures had a normalization of calcitonin in 10.5 % of patients (95 % CI 6.4-14.7), while compartment-oriented procedures had a higher rate of normalization at 18.6 % (95 % CI 15.9-21.3). The rate of calcitonin normalization after reoperation for MTC is enhanced through use of a meticulous compartment-oriented lymph node dissection. Compartment-oriented lymph node dissection results in calcitonin normalization in 18.6 % of reoperative MTC patients and is the procedure of choice in patients in whom the goal is biochemical cure.