Using foci number to predict central lymph node metastases of papillary thyroid microcarcinomas with multifocality

The aim of our study is to analyze the clinicopathological characteristics and treatment options for papillary thyroid microcarcinomas with multifocality and investigated whether the number of foci in papillary thyroid microcarcinomas with multifocality can predict central lymph node metastases. Methods Records of 329 consecutive PTMC patients with multifocality, and who were treated surgically between 2003 and 2014 were reviewed. Patients with multifocality were identified by histopathology. The number of foci, size of the largest tumour, presence of extrathyroidal invasion, infiltration, and other clinicopathological parameters were collected and analyzed for all the cases.

Univariate analysis, age, sex, maximum tumour size, and extrathyroidal invasion were found to be significant prognostic factors (P = 0.001, 0.020, < 0.001, 0.043; respectively). Multivariate analysis found that age, sex, and maximum tumour size were independent prognostic factors for CLNM in PTMCs. Among them, Male patients (odds ratio 1.887; 95% confidence interval [CI] 1.053-3.380) and with maximum tumour size > 0.5 cm (odds ratio 2.819; 95% CI 1.721-4.616) were risk factors for increased incidence of CLNM. Patients ≥ 45 years (odds ratio 0. 497; 95% CI 0.309-0.800) were less likely to present with CLNM. However, extrathyroid invasion was not an independent predictor of CLNM according to our results. PTMCs with 2, 3, ≥ 4 foci had a significantly greater risk of CLNM (odds ratio 1.675, 2.360, 2.703; 95% CI 1.195-2.347, 1.425-3.906, 1.411-5.178; respectively) compared to PTMCs with unifocality.

Foci numbers were linked to an increased incidence of central lymph node metastases in papillary thyroid microcarcinomas with multifocality, and we could choose to perform more radical treatment in patients with multifocality.