Serum Small Proline-Rich Protein 2A (SPRR2A) Is a Noninvasive Biomarker in Gastric Cancer

OBJECTIVE: Since early diagnosis is very important for treating gastric cancer (GC), we aimed to detect serum small proline-rich protein2A (SPRR2A) to verify its diagnostic value for GC patients. METHODS: Serum samples were collected from 200 patients with GC, 100 patients with gastritis, 40 patients with rectal cancer (RC), 50 patients with colon cancer (CC), and 100 healthy controls. An enzyme-linked immunosorbent assay (ELISA) detection kit was applied to measure serum SPRR2A concentration. The correlations between serum SPRR2A and carcinoembryonic antigen (CEA), clinical pathological parameters of GC, and receiver operating characteristic (ROC) curve were also analyzed. RESULTS: The median serum SPRR2A concentration in GC patients was significantly higher than those in healthy controls and gastritis or colorectal cancer patients (P < 0.001). Serum SPRR2A concentration at a cut-off value of 80.7 pg/ml yielded an AUC of 0.851, with 75.7% sensitivity and 74.5% specificity for discriminating GC patients from healthy people. The AUC for the serum SPRR2A concentration combined with the CEA concentration was 0.876, with 79.7% sensitivity and 78.7% specificity. Similarly, serum SPRR2A discriminated GC patients from gastritis patients with an AUC of 0.820, with 90.5% sensitivity and 61.7% specificity. The AUC for the serum SPRR2A concentration combined with the CEA concentration was 0.848, with 87.8% sensitivity and 68.1% specificity. The serum SPRR2A levels in GC patients were associated with lymph node metastasis and the tumor-node-metastasis (TNM) stage (P < 0.05). There was an obvious difference in serum SPRR2A expression between GC patients before and after surgery (P < 0.0001). CONCLUSION: These results suggest that serum SPRR2A can be used as an effective marker for GC.