Central Neck Dissection Cannot Be Avoided In Medullary Thyroid Cancer (MTC) On The Basis Of Presurgical Serum Calcitonin (CT)

Objectives: While it is well known that lymphnode metastases (LNF- mets) have never found in RET gene carriers with a basal presurgical CT <30-40 pg/ml, to our knowledge there are no studies about this issue in spo- radic adult MTC patients. The aim of the study was to look for a pre-operative serum CT value able to predict the absence of central nodes metastases, in order to avoid the lymphadenectomy of the central neck compartment (CCL) which is affected by a higher prevalence of complications. Methods: We retrospectively analyzed the clinico-pathological and molecular features of MTC patients underwent surgery at our Department between 2005 and 2015. In this period we changed the laboratory assay for CT assessment: before September 2013 we used an immunometric assay [ELSA- hCT; Cis-BioInternational, Gif sur Yvette, France, normal value <10 pg/ml both in males and females], after September 2013 we used an immunoassay method [Immulite 2000, DPC, LA, USA, normal values <11.5 pg/ml and <18.2 pg/ml in females and males respectively]. Results: A total of 306 MTC patients underwent total thyroidectomy (TTX) and CCL in this study period. They were divided into 2 subgroups according to the assay used: group I (n=200) (CT assay ELSA-hCT) and group II (n=50) (CT assay Immulite). Thirty-seven/200 patients of group I and 13/50 of group II had LFN-mets at histology. The highest value of CT able to iden- tify all negative cases was 14 pg/ml in group I and 12.6 pg/ml (for female) and 18.6 pg/ml (for males) in group II which are, in both assays, very close to the upper limit of normal values. Conclusions: We didn’t find a preoperative CT cut-off able to identify MTC patients certainly not complicated by LNF-mets. According to our results all MTC adults patients should underwent at least TTX+CCL.