Endocrine Abstracts

Objective: The clinical course of metastatic lymph nodes in patients with differentiated thyroid cancer is unclear, due to the lack of universal criteria defining disease progression. The aim of the present study was to evaluate the characteristics of suspicious lymph nodes in patients with differentiated thyroid cancer, in order to distinguish lesions with an indolent behaviour and to identify potential predictors of disease progression.

Methods: We retrospectively studied 122 patients with ≥1 cervical lymph node suspicious for metastasis upon first-line treatment for thyroid cancer. We evaluated the growth of the target (i.e., the largest) lesion. We compared patients whose target lesion displayed an indolent behaviour (growth rate >3 mm/year) and patients with a faster increase in size of the target lymph node (growth rate >3 mm/year), aiming to assess potential outcome predictors.

Results: Patients with lymph nodes growing >3 mm/year (12.3%) were older (P = 0.0003), with significantly more advanced and aggressive primary tumours. Their target lesions were more frequently in the lateral neck (P = 0.031) and were larger (P = 0.003) at diagnosis. Around 45% of these patients developed distant metastases (versus 9.3%, P = 0.0001) and they more commonly required second-line treatments (P = 0.0002). Following a multivariate logistic regression analysis, the diameter of the target lesion at diagnosis resulted an independent positive predictor of a target LN growth rate >3 mm (Odds Ratio (OR) 1.71, 95% Confidence Interval (CI) 1.27-2.29). An initial diameter >8 mm was identified as the best threshold to differentiate suspicious lymph nodes growing >3 mm/year. We also compared subjects with and without distant metastases, to identify potential predictors of a more aggressive disease. A widespread disease was significantly associated with an older mean age at tumour diagnosis (56.7 versus 40.2 years, P = 0.0005), larger (median diameter: 30 versus 15 mm, P = 0.0024) primary tumours with a higher risk of recurrence (ATA high risk: 7/17 (41.2%) versus 17/105 (16.2%), P = 0.021), and more frequent presence of suspicious target lesions in the LC (9/17 (51.9%) versus 27/105 (25.7%), P = 0.023). At the multivariate analysis, the target LN diameter resulted an independent predictor of distant metastases (OR 7.18, 95% CI 2.19-23.5).

Conclusions: In thyroid cancer patients, about 88% of suspicious lymph nodes enlarge slowly over time, with active surveillance being a feasible strategy for their management. Suspicious lesions >8 mm are at higher risk of growing >3 mm/year, are more frequently associated with distant metastases, and more likely need further treatments.