The occult nodal metastasis rate of early tongue cancer (T1–T2): A protocol for a systematic review and meta-analysis

OBJECTIVES: In this study, a meta-analysis was conducted to evaluate the occult lymph node metastasis rate in patients with early-stage (T1–T2) oral tongue squamous cell carcinoma. Also, the correlation between occult lymph node metastasis rate and T2 ratio among T1–T2 or the reported year of each study was analyzed to adjust other confound variables. STUDY DESIGN: Literature search. METHODS: A systematic computerized search of the electronic databases was carried out for articles published between January 1, 1980, and December 31, 2018, which reported occult nodal metastasis rate in T1 and T2 (separately) tongue cancer patients. Statistical analysis was performed using Comprehensive Meta Analysis version 3.3.070. Publication bias was assessed by the Egger test and Begg funnel plot method. The correlation between occult nodal metastasis rate and T2 ratio or reported year, respectively, was assessed by meta-regression analysis. RESULTS: From 19 studies, a total of 1567 cases were included in the meta-analysis. By random effects model, the mean occult cervical lymph node metastasis was 24.4% (95% confidence interval; 0.205–0.248). The meta-regression revealed that the T2 ratio and the reported year of the studies did not have a significant effect on the occult metastasis rate (correlation coefficient = 0.531 and 0.002, respectively, and P = .426 and 0.921, respectively). CONCLUSION: The meta-analysis revealed that the early-stage oral tongue squamous cell carcinoma had a rate of 24.4% for occult nodal metastasis. The occult nodal metastasis rate was not significantly affected by neither T2 ratio among T1–T2 nor reported year of the studies.