Surgical Extent and Preoperative Planning: Impact on Outcomes in Medullary Thyroid Carcinoma

Purpose: To evaluate the impact of surgical practices that deviate from international guideline recommendations on clinical outcomes in medullary thyroid carcinoma (MTC), and to investigate factors influencing preoperative calcitonin (CT) levels to improve patient-specific surgical decision-making. Methods: This retrospective study included 91 patients with histologically confirmed MTC who were followed from January 2019 to March 2025 at a single tertiary care centre. Patients who underwent thyroidectomy before or during the follow-up period and had at least 6 months of postoperative monitoring were included. Clinical, radiological, surgical, and pathological parameters were analyzed. The extent of surgery was compared with the ATA-2015, ESMO-2019, and NCCN-2025 guidelines. Associations between CT levels and tumour characteristics were assessed statistically. Clinical outcomes, including persistent disease and reoperation, were assessed in relation to the extent of the surgical procedure. Results: Among 91 patients with MTC, surgical procedures differed from guideline recommendations by 32.3% for ATA, 70.8% for ESMO, and 40.0% for NCCN. These deviations—whether less or more extensive—did not significantly impact rates of persistent disease or reoperation. Persistent disease occurred in 23.1% of patients and was significantly linked to higher preoperative CT levels, larger tumor size, and bilaterality. Tumor size correlated with metastatic lymph node involvement across all cervical compartments, but preoperative CT levels only predicted ipsilateral lateral lymph node metastasis. ROC analysis identified a CT cut-off of 189.5 pg/ml for predicting ipsilateral lateral LN metastasis, with 92.3% sensitivity and 61.8% specificity. Conclusion: Deviations from guideline-recommended surgical extent, when based on patient-specific findings, do not compromise clinical outcomes. Tumor size should be considered in conjunction with CT levels to inform personalized surgical strategies in MTC.