Diagnostic role of Ki-67 expression in distinguishing thyroid follicular carcinoma from follicular adenoma: a systematic review and meta-analysis.

Abstract

Background: Differentiating follicular thyroid carcinoma (FTC) from follicular adenoma (FA) is challenging due to their histological similarities. This systematic review and meta-analysis aimed to assess the difference in Ki-67 expression between FTC and FA to evaluate its diagnostic utility.

Methods: We conducted a comprehensive search of PubMed, Embase, Scopus, and Web of Science databases for studies reporting Ki-67 expression in FTC and FA. The quality of the included studies was assessed using the Newcastle-Ottawa Scale. A random-effects model was applied to calculate the pooled mean difference of the Ki-67 index, with heterogeneity assessed by the Cochran Q and I-squared tests. Meta-regression was used to explore sources of heterogeneity, and publication bias was evaluated using Egger's test, Begg's test, and funnel plot.

Results: The meta-analysis revealed a pooled mean difference in Ki-67 expression between FTC and FA of 1.13 (0.63-1.63), indicating a significant difference. In addition, the difference in the Ki-67 index between minimally invasive follicular carcinoma and FA was 0.56 (0.12-1.00), which was also statistically significant. The heterogeneity among included studies was due to variations in Ki-67 index calculation methods. The reviewed studies demonstrated low sensitivity but high specificity of Ki-67 for differentiating FTC vs. FA, although diagnostic cut-offs were inconsistent.

Conclusions: This study demonstrates a significant difference in Ki-67 expression between FTC and FA, supporting its potential role as a diagnostic marker. Further research is required to establish standardized diagnostic cut-offs and evaluate Ki-67's sensitivity and specificity in clinical practice.