Positive peritoneal washing cytology in multiple cavities can predict poor prognosis of advanced gastric cancer patients.

Background: Positive peritoneal washing cytology (PWC) has been reported to be a poor prognostic factor for gastric cancer. Japanese gastric cancer classifications recommend PWC in Douglas' pouch for advanced gastric cancer. However, the sensitivity of PWC is relatively low. The goal of this study was to investigate whether PWC in multiple cavities increases its sensitivity to predict prognosis.

Methods: Between January 1996 and December 2006, a series of 992 patients with gastric cancer underwent D2 gastrectomy with intraoperative PWC. Of the 992 patients, 62 patients had positive PWC. PWC was conducted in four cavities (left subphrenic cavity, right subhepatic cavity, Douglas' pouch, and inside the omental bursa). The 62 patients were retrospectively analyzed for their background and survival.

Results: Eleven (17.7%) patients had negative PWC in Douglas' pouch but were positive in the other cavities. The 62 patients were classified into two groups according to the number of positive PWC cavities: 20 patients with one or two and 42 patients with three or four positive PWC cavities. No significant difference in clinicopathological features was observed between these two groups. However, the overall and progression-free survival rates of patients with one or two positive PWC cavities were significantly higher than those for patients with three or more positive PWC cavities.

Conclusion: PWC in multiple cavities was more sensitive than only in one cavity. The number of positive cavities may indicate the grade of tumor spread in the peritoneum and predict the prognosis of patients with positive PWC.