Use of mRNA levels in formalin-fixed paraffin-embedded tissues as a biomarker to diagnose gastric cancer and to evaluate the extent of vascular invasion.

With the recent advances in medical technologies, gastric cancer can often be removed with minimally invasive surgical techniques when identified early. Surgery must remove all gastric cancer, since residual cancerous tissue may lead to recurrence. Resected cancerous tissues are pathologically evaluated to determine whether all cancerous areas have been removed, but such assessments are rarely straightforward, and cancer markers could inform such pathological evaluations of cancer. An ideal marker would be identifiable in formalin-fixed paraffin-embedded (FFPE) tumor tissue. The first objective of the present study was to compare levels of angiopoietin-like protein 2 (ANGPTL2) in cancerous and noncancerous areas of FFPE tissues to determine whether ANGPTL2 is a marker relevant to the pathological diagnosis of cancer. The second objective was to evaluate whether mRNA is useful as a marker of the extent of vascular invasion of gastric cancer. Out of the 15 patients studied, 12 had a higher mRNA levels in cancerous areas compared with noncancerous areas. This finding indicated that mRNA is useful as a biomarker for identifying cancerous areas in FFPE tissues, at least for male patients. Spearman's rank correlation analysis showed a significant correlation between the mRNA level and the degree of vascular invasion of cancer (r=0.66; P=0.01). In receiver operating characteristic curve analysis of the association between the mRNA level and the degree of vascular invasion, the area under the curve was 0.92 (95% confidence interval, 0.78-1.00; P=0.01), indicating a significant association. The present study demonstrates that mRNA in FFPE tissues is a potential biomarker that informs the pathological diagnosis of gastric cancer and that mRNA may be predictive of vascular invasion, which is an indicator of metastasis in gastric cancer.