Risk factors for cervical lymph node metastasis in papillary thyroid microcarcinoma: A meta-analysis

A number of studies of predictive factors for lymph node metastasis in papillary thyroid microcarcinoma have been published. We conducted a systematic meta-analysis of some of these studies, and we present our findings herein. We searched the PubMed database and found 13 eligible studies and case series of papillary thyroid microcarcinoma that were published in the English-language literature from January 2001 through December 2012, and we analyzed their findings. The most commonly investigated tumor characteristics associated with lymph node metastasis were size, multifocality, capsular invasion, and lymphovascular invasion. With regard to the risk of developing lymph node metastasis, patients with larger tumors had a 1.93 greater chance (95% confidence interval [CI]: 1.36 to 2.73, p < 0.001), those with multifocal tumors had a 3.03 greater chance (95% CI: 2.05 to 4.47; p < 0.001), those with capsular invasion had a 4.13 greater chance (95% CI: 2.40 to 7.10; p < 0.001), and those with lymphovascular invasion had a 2.76 greater chance (95% CI: 1.50 to 5.07; p = 0.005). We conclude that patients with larger and/or multifocal papillary thyroid microcarcinomas and tumors associated with capsular or lymphovascular invasion have a significantly greater risk of developing lymph node metastasis.