Surgical strategy for the treatment of sporadic medullary thyroid carcinoma: our experience

Medullary thyroid carcinoma (MTC) is a rare disease which accounts for approximately 5-9% of all thyroid cancers and originates from the calcitonin-screening parafollicular C cells. MTC can be divided into two subgroups: sporadic (75%) or inherited (25%). The majority of patients with invasive MTC have metastasis to regional lymph nodes at the time of diagnosis, as evidenced by the frequent finding of persistently elevated calcitonin levels after thyroidectomy and the high rates of recurrence in the cervical lymph nodes reported in retrospective studies.

The purpose of the study is to review our single institution's experience with MTC since 1998 and to evaluate surgical strategy, patterns of lymph node metastases and calcitonin response to compartment-oriented lymphadenectomy in patients with primary or recurrent sporadic medullary thyroid carcinoma.

A retrospective review of 26 patients treated for MTC at the "Antonio Cardarelli" Hospital referral center, in Naples, between 1998 and 2012. There were 18 female and 8 male patients, median age at presentation was 55 years, and median follow-up for survivors was 5 years. Total thyroidectomy was performed in all 26 patients; central compartment (CC) node dissection (level VI) in 12 (46%) patients; central plus lateral compartment (LC) node dissection (levels II, III, and IV) in 7 (27%) patients. 4 patients (15%) underwent reoperation for loco-regional recurrent/persistent MTC. Results. After a median post-surgical follow-up of 5 years (range 1-10 years), 63 % of patients were living disease-free, 15% were living with disease and/or persistently elevated calcitonin levels after surgery, 11% were deceased due to MTC and 11 % were lost to follow-up.

We agree with most authors advocating for a total thyroidectomy and prophylactic central neck dissection in the setting of clinically detected MTC. Lateral neck dissection may be best reserved for patients with positive preoperative imaging. Nevertheless MTC has a high rate of lymph node metastases that are sub optimally detected preoperatively in the central compartment by neck ultrasound or intra-operatively by the surgeon, and reoperation is associated with a higher rate of surgical complications. In our limited experience, patients with thyroid confined nodular pathology, without nodal disease and unknown preoperative diagnosis of MTC, underwent only total thyroidectomy with a good prognosis.