Risk factors for lymph node metastasis in T1 esophageal squamous cell carcinoma: A systematic review and meta-analysis

Figure 1 The flow chart of the selection process for the studies included in this meta-analysis. In total, 1527 records were identified from all sources (Embase, PubMed, and Cochrane Library). Only 17 studies involving 3775 patients met all inclusion criteria and were selected for the meta-analysis.

Figure 2 Forest plot. A: Forest plot evaluating the association between age (> 60/≤ 60) and lymph node metastasis (LNM); B: Forest plot evaluating the association between sex (male/female) and LNM. CI: Confidence interval; IV: Inverse-Variance; M-H: Mantel-Haenszel.

Figure 3 Forest plot. A: Forest plot evaluating the association between tumor size (> 2/≤ 2) and lymph node metastasis (LNM); B: Forest plot evaluating the association between tumor location (lower/upper-middle) and LNM; C: Forest plot evaluating the association between macroscopic type (nonflat/flat) and LNM. CI: Confidence interval; M-H: Mantel-Haenszel.

Figure 4 Forest plot. A: Forest plot evaluating the association between T1 substage (T1a/T1b) and lymph node metastasis (LNM); B: Forest plot evaluating the association between differentiation (poorly differentiated/well differentiated-moderately differentiated) and LNM; C: Forest plot evaluating the association between lymphovascular invasion (present/absent) and LNM; D: Forest plot evaluating the association between infiltrative growth pattern (c/a-b) and LNM. CI: Confidence interval; G1/2: Well differentiated/moderately differentiated; G3: Poorly differentiated; M-H: Mantel-Haenszel.