Endocrine Abstracts

Introduction: Medullary thyroid cancer (MTC) TNM classification categorizes lymph nodes (LN) according to their location, but does not consider number and size of LN.

Objective: To analyze the relationship between number and size of LN in MCT persistent disease (PD).

Material and methods: Retrospective study of patients with MTC followed up in a regional hospital from 1985 to 2015. The main variables (expressed as qualitative in frequency and quantitative as mean±S.D. or median (min-max)): size of largest LN, number of node, extracapsular involvement and number of LN surgical procedures undertaken. Univariate analysis was used to assess the relationship between LN number and TMN stage with PD or remission. A P-value less than <0.05 was considered significant.

Results: Thirty-five patients were included (age at diagnosis 51±18 years; 57% women). Time to follow up:8.6±7.2 years. Presentation: 24% cervical mass, 38% through family screening, 8% as incidentalomas. Before surgery, calcitonin levels were 391 pg/ml (2-46022) and carcinoembryonic antigen levels were 11.8 ng/ml (0-2009). TNM stage: I:47%; II:6%; III:12%; IV:35%. N0:37%; NX:20%, N1:43%(N1a:33%; N1b:67%). Size of greatest LN:2.5±1.6 cm (< 1 cm: 23%; 1–3 cm: 46%; >3 cm: 31%). Number of node: 1(0–22) (< 5 LN:64%; 5–9 LN:14%;≥10 LN:22%). Extracapsular involvement: 29%. Number of LN surgery: 1±0.67 (0–4). At the last visit, 47% had PD.

Univariate analysis:: We found clinical differences, although they were not significant, in LN size (PD 31±15 mm vs remission 10±14 mm (P 0.058)). The percentage of patients who reached remission was 0%(0/5) with extracapsular involvement vs 50%(5/10) without extracapsular involvement (P 0.053). Among 15 patients with N1category, only three were cured (all had< 5 LN and a size LN< 2 cm).

Conclusion: In our case series we observed that N category and number of LN is associated with PD in the long term. Furthermore, there was a linear trend between the size of the greatest LN and the extracapsular imvolvement with the PD. This reinforces the importance of a correct characterization of LN involvement.