The role of two tumor foci for predicting central lymph node metastasis in papillary thyroid carcinoma: A meta-analysis

Two tumor foci are the most common in multifocal papillary thyroid carcinoma, but whether they should be regarded as the indicator of central lymph node metastasis remains unclear. To investigate the role of two tumor foci for predicting central lymph node metastasis, we performed a meta-analysis of published studies. We performed a systematic literature search of PubMed, Embase and Web of Science prior to September 29, 2017. The relevant articles were examined and the eligible studies were included to assess the metastatic risk of central lymph node in papillary thyroid carcinoma with one, two and more than two (>2) tumor foci. Five eligible studies included 4045 patients in this meta-analysis. Two tumor foci were the most common in multifocal papillary thyroid carcinoma (63.8%, 939/1471). Multifocality group showed a higher risk of central lymph node metastasis compared with unifocality group (odds ratio: 1.58, 95% confidence interval: 1.37–1.81). The risk of central lymph node metastasis was higher in two tumor foci group than unifocality group (odds ratio: 1.38, 95% confidence interval: 1.17–1.62). However, this risk in two tumor foci group was lower than >2 tumor foci group (odds ratio: 0.62, 95% confidence interval: 0.42–0.92). Begg's test revealed no obvious publication bias. This meta-analysis suggested that two tumor foci should be regarded as the predictive factor of central lymph node metastasis, but the role of it was less important than three or more than three tumor foci. Understanding the role of two tumor foci for predicting central lymph node metastasis may help clinicians make an optimal decision of treatment and the extent of surgery for multifocal papillary thyroid carcinoma.