Diagnostic value of preoperative RT-PCR-based screening method to detect carcinoembryonic antigen-expressing free cancer cells in the peritoneal cavity from patients with gastric cancer.

BACKGROUND

At present the most reliable method for the diagnosis of peritoneal micrometastasis of gastric cancer is peritoneal wash cytology, but the sensitivity of this method is low. The aim of the present study was to verify whether carcinoembryonic antigen (CEA) reverse transcriptase-polymerase chain reaction (RT-PCR) assay can enhance the sensitivity and specificity of conventional cytology, and to determine how this technique can improve the accuracy of peritoneal recurrence.

METHODS

The present study included 230 patients with gastric cancer. Preoperative peritoneal wash was done by a paracentesis, followed by conventional cytology, CEA measurement, and CEA RT-PCR of recovered fluid.

RESULTS

The CEA RT-PCR assay yielded 40 (17%) positives, which included none of the 26 patients with benign disease. The incidence of positive cytology and CEA level in wash fluid was 19% and 15%, respectively. Logistic stepwise regression analysis revealed that lymph node status, depth of invasion, venous invasion, and the results of peritoneal cytological examination, and CEA RT-PCR assay were independently related to peritoneal recurrence. The CEA level in the wash fluid was not related to peritoneal recurrence. Peritoneal cytological examination was the most significant predictive factor for peritoneal recurrence with a sensitivity of 46%, specificity of 94% and accuracy of 73%, while the corresponding values of the CEA RT-PCR assay were 31%, 95%, and 73%. Combining cytological examination with CEA RT-PCR assay resulted in a sensitivity rate for peritoneal recurrence of 57%, an 11% improvement over that of cytology alone.

CONCLUSION

The data indicate that the use of a combination of CEA RT-PCR and cytological assay is more likely to identify patients who will develop peritoneal recurrence. This may be useful for the classification of patients for the most suitable therapeutic trials.