Endocrine Abstracts

Background: Locoregional nodal metastases are the first step of tumor spread in MTC and have been shown to be a prognostic factor for survival. Neither palpation nor neck ultrasound can estimate nodal staging accurately.

Aim: To identify predictive factors for LNI in MTC through a retrospective study on 142 consecutive patients operated in Lille University Hospital between 1995 and 2010.

Methods: Analyses were carried on 54 patients (median age=52 (41–61), M/F ratio=0.54; mean tumor size=25 mm (15–35), median calcitonin (CT) value=1177 pg/ml (304–3470)) after exclusion of familial MTC (n=38) and microMTC (n=27). Total thyroidectomy plus LN dissection was performed in 98%. Pathologic slides were reviewed. Pre and postoperative CT (pre/postCT) were all available.

Results: Twenty-six (48%) patients with a sporadic macroCMT had LNI, 6 (23%) of whom had a curative resection confirmed by undetectable postCT. All LN free cases had accordingly undetectable postCT. Thirty three percent of MTC with preCT>2000 pg/ml were unexpectedly LN free with undetectable postCT. Under univariate analysis, age and tumor size did not influence LN status. Male patients (P=0.027) and higher preCT level (P=0.001) were more likely associated with LNI. Positive correlation was observed between LNI and DSR (P=0.001), no peritumoral capsule (P=0.001), peritumoral invasion (P=0.00004), vascular invasion (P=0.0004) and ETI (P=0.003). Multivariate analysis showed both DSR (OR=131.67; P<0.0001) and ETI (OR=255.03; P=0.01) to be independent factors for LNI. The rate of RET somatic mutation found in 45% of 29 analyzed tumors was not significantly higher in MTC with LNI.

Conclusion: At surgery, 52% of sporadic macro CMT was LN free. Though higher preCT may be indicative of LNI no threshold can be set. Since no preoperative factor can ascertain nodal status, a systematic LN dissection is still requiered. ETI and DSR are strong predictors of LNI: their impact should be addressed on further survival studies.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.

Figure 1 Invasive MTC with an important DSR.