Microarray Analysis of Peritoneal Wash Samples to Predict Recurrence of Gastric Cancer

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Advanced gastric cancer is often an incurable disease because of lymphogenous, hematogenenous and peritoneal recurrence. Identification of the highly sensitive and specific multiple markers, which aid to predict the risk of recurrence at the initiation of therapy, is eagerly awaited to select the best therapeutic modality for each case. Cells recovered by peritoneal lavage may offer a unique opportunity for a gene expression based analysis. Using a microarray of 12,626 genes, we first searched for genes whose mRNAs were not only undetectable in all peritoneal washes of 8 early gastric cancer patients, but were also abundant in at least one of 12 gastric cancer cell lines. Eleven genes specific to cytology-positive samples were identified by the RT-PCR analysis. Among them, 5 genes including CK20 were highly specific (100%, 98%, 100%, 93% and 91%, respectively) in 104 samples, while specificity of CEA was 82%. Furthermore, not only peritoneal but also non-peritoneal recurrences within 2 years were associated with the positive RT-PCR results on the peritoneal wash samples.