Risk factors for lymph node metastasis in papillary thyroid microcarcinoma: Older patients with fewer lymph node metastases.

BACKGROUND

Lymph node metastasis (LNM) is an important consideration in treatment strategy selection for papillary thyroid microcarcinoma (PTMC). The aim of this study was to investigate the risk factors for LNM and high-volume LNM (hvLNM, >5 metastatic lymph nodes).

METHODS

A consecutive series of 1226 PTMC (947 female, 279 male) patients was reviewed. All patients underwent at least central neck dissection. Clinical-pathological features were assessed. All patients were allocated into Group A (≤39 yrs), Group B (40-59 yrs), or Group C (≥60 yrs) for risk factor analysis.

RESULTS

Among all patients, 438 LNM and 73 hvLNM were detected. Older patients had significantly fewer LNM (A: 51.45% of 346, B: 30.15% of 786, and C: 24.47% of 94) and fewer hvLNM (A: 11.85%, B: 3.94%, and C: 1.06%). Male, multifocality, and tumor diameter >0.5 cm were also correlated with LNM and hvLNM. In multivariate analysis, older patients had lower risk of LNM (odds ratio [OR] 0.389 in B, 0.305 in C), and chronic thyroiditis was protective factor for LNM (OR 0.524). Male (OR 1.651), tumor diameter >0.5 cm (OR 1.850), and multifocality (OR 1.928) were risk factors for LNM. Similarly, older patients had lower risk of hvLNM (OR 0.313 in B, OR 0.085 in C). Male (OR 2.590), tumor diameter >0.5 cm (OR 2.180), and multifocality (OR 1.980) were also risk factors for hvLNM.

CONCLUSION

Older PTMC patients may have fewer LNM and lower risk of hvLNM. For patients ≥60 years old, dynamic observation may be an option for clinical management.