Absolute quantification of free tumor cells in the peripheral blood of gastric cancer patients.

Abstract

Gastric cancer remains the third most common cancer in the world. Metastatic disease is a major cause of death in about half of the patients; therefore, early diagnosis is crucial for successful outcome. This study applied a sensitive method for the detection of circulating tumor cells using specific tumor markers for early detection. A total of 80 blood samples from 40 patients and 40 age-matched healthy controls were collected for the study. Circulating mRNA levels of two tumor markers, tumor endothelial marker 8 (TEM-8) and carcinoembryogenic antigen (CEA) were evaluated using absolute quantitative real-time PCR assay in the Stratagene Mx-3000P real-time PCR system. GAPDH was used to normalize the data. TEM-8 and CEA were detected in patients' blood more than in controls, 22/40 vs 9/40, P=0.005, and 30/40 vs 11/40, P=0.008, respectively. The mRNA level of these markers in patients was significantly higher in comparison to normal controls (P=0.018, 0.01). This panel showed an overall sensitivity of 64% and specificity of 73%. Statistical analysis for demographic variants did not show any significant differences. Both markers were detected more frequently and in significantly higher levels in blood samples of patients compared to samples from normal individuals. Copy number of CEA and TEM-8 mRNA, as detected by real-time quantitative PCR, appears to be a promising marker to evaluate the risk of tumor spread.