Correlation analysis further revealed a significant positive correlation between intratumoral and peripheral Ki67+ Tregs (Spearman R = 0.45, P < 0.001; Fig. 4f), suggesting that circulating Ki67+ Treg cells are associated with tumor-infiltrating Treg cells and can reflect the abundance of proliferative Tregs in the TME. This evidence concerns the gene MKI67 and neoplasm.