Association of gene expressions of TOP2A, GGH, and PECAM1 with hematogenous, lymph-node, and peritoneal recurrence in patients with stage II/III gastric cancer enrolled in the ACTS-GC study.

Abstract

4019 Background: Exploratory biomarker analysis was conducted to identify factors related to relapse sites in the ACTS-GC study, a randomized controlled trial comparing postoperative adjuvant S-1 therapy with surgery alone in 1,059 patients (pts) with stage II/III gastric cancer. Methods: Formalin-fixed, paraffin-embedded surgical specimens were retrospectively examined in 829 pts (78.3%), and 63 genes involved in pyrimidine metabolic pathway, growth factor signaling pathway, apoptosis, DNA repair, etc., were analyzed by quantitative RT-PCR after TaqMan assay-based pre-amplification. Gene expression levels were normalized to the geometric mean expressions of GAPDH, ACTB, and RPLP0, used as reference genes. The expression of each gene was categorized as lower or higher than the median value. The impact of gene expression on relapse site was analyzed using the 5-year relapse-free survival (RFS) data of the ACTS-GC. Results: Among the 829 pts, hematogenous, lymph-node, and peritoneal recurrence developed in 72, 105, and 138 pts, respectively. The hazard ratios (HR) (S-1 vs. surgery alone) were 0.79 (95%CI, 0.54-1.16) for hematogenous, 0.51 (95%CI, 0.31-0.82) for lymph-node, and 0.60 (95%CI, 0.42-0.84) for peritoneal recurrence. Among 63 screened genes, topoisomerase II alpha (TOP2A), gamma-glutamyl hydrolase (GGH), and platelet/endothelial cell adhesion molecule 1 (PECAM1) most strongly correlated with hematogenous, lymph-node, and peritoneal recurrence, respectively. Hematogenous RFS was significantly worse in TOP2A high pts than in low pts (HR, 2.35; 95% CI, 1.55-3.57). Lymph-node RFS was significantly worse in GGH high pts than in low pts (HR, 1.87; 95% CI, 1.13-3.08). Likewise, peritoneal RFS was significantly worse in PECAM1high pts than in low pts (HR, 2.37: 95% CI, 1.65-3.41). These factors were independent and stronger risk factors than tumor histological type on multivariate analysis. Conclusions: Expression levels of the TOP2A, GGH, and PECAM1 genes in primary tumors are respectively linked to high risks of hematogenous, lymph-node, and peritoneal recurrence in pts with stage II/III gastric cancer.