Detection of cancer cells and gene expression of cytokines in the peritoneal cavity in patients with gastric cancer

Abstract

Background. The gene expression of the cytokines interleukin-2 (IL-2) and IL-10 in peritoneal washings was examined in relation to the presence of cancer cells in the peritoneal cavity in patients with gastric cancer. Methods. Total RNA was extracted from 50-ml peritoneal wash samples from 124 patients (gastric cancer, n = 110; controls, n = 14). Carcinoembrionic antigen (CEA) messenger RNA (mRNA) was used to identify the number of cancer cells in peritoneal wash samples by a real-time reverse transcription-polymerase chain reaction (RT-PCR) method, which method was also used to assay the IL-2 and IL-10 gene expression levels. Results. In the 14 control samples, CEA mRNA was not detected, while CEA mRNA was detected in 2 of the 51 stage I gastric cancer patients. Thus, the specificity of this method for the detection of cancer cells in peritoneal wash samples was 97% (63/65). The CEA-based real-time RT-PCR method demonstrated greater prognostic impact than the traditional cytological method. IL-2 gene expression in peritoneal wash samples that were CEA mRNA-positive was suppressed compared with that in peritoneal wash samples that were CEA mRNA-negative, while IL-10 gene expression did not differ according to the CEA mRNA findings. Conclusion. The detection of small numbers of cancer cells in peritoneal wash samples from patients with advanced gastric cancer is a good marker for peritoneal metastatic recurrence. In the peritoneal cavity, cancer cells may escape from immune surveillance by controlling the expression of cytokines. © 2006 International and Japanese Gastric Cancer Association.