Free cancer cells exfoliated from cancer-invaded serosa contribute to peritoneal dissemination, the most frequent pattern of recurrence in patients with gastric cancer. To detect free cancer cells, CEA and CA19-9 were introduced as the markers of gastric cancer, and many methods, such as cytology, immunoassay, and reverse transcription polymerase chain reaction (RT-PCR), exist for detecting them. The aim of this study is to define the clinical significance of using immunoassay to measure the levels of CEA and CA19-9 in the peritoneal washings in patients with gastric cancer.

The peritoneal washing fluids were obtained from 130 patients with gastric cancer who received a curative gastrectomy, palliative gastrectomy or open and closure. The pCEA and pCA19-9 levels were measured by using immunoassay and cytology. The results were compared with the clinicopathological data.

The pCEA and pCA19-9 levels were correlated with tumor invasion, lymph-node metastasis, and stage (P<0.05).

A correlation was found between elevated pCEA and pCA19-9 levels measured by immunoassay and the TNM stage. Therefore, a combined pCEA and pCA19-9 assay could be a sensitive detector of peritoneal dissemination, as well as a predictor of postoperative prognosis. pCEA and pCA19-9 may also determine the adjuvant management strategy.