Rapid Staining Using the Shorr Method for Intraoperative Peritoneal Washing Cytology in Advanced Gastric Cancer: a Pilot Study from a Single Institution

Purpose: Intraoperative peritoneal washing cytology (PWC) is used to determine treatment strategies for gastric cancer with suspected serosal invasion. However, a standard staining method for intraoperative PWC remains to be established. We evaluated the feasibility of a rapid and simple staining method using Shorr's stain for intraoperative PWC in advanced gastric cancer. Materials and Methods: Between November 2012 and December 2014, 77 patients with clinical T3 or higher gastric cancer were enrolled. The sensitivity, specificity, and concordance between the Shorr staining method and conventional Papanicolaou (Pap) staining with carcinoembryonic antigen (CEA) immunohistochemistry (IHC) were analyzed. Results: Intraoperative PWC was performed laparoscopically in 69 patients (89.6%). The average time of the procedure was 8.3 minutes, and the average amount of aspirated fluids was 83.3 mL. The average time for Shorr staining and pathologic review was 21.0 minutes. Of the 77 patients, 16 (20.7%) had positive cytology and 7 (9.1%) showed atypical findings; sensitivity and specificity were 73.6% and 98.2% for the Shorr method, and 78.9% and 98.2% for the Pap method with CEA IHC, respectively. Concordance of diagnosis between the 2 methods was observed in 90.9% of cases (weighted. statistic=0.875) and most disagreements in diagnoses occurred in atypical findings (6/7). In overall survival, there was no significant difference in C-index between the 2 methods (0.459 in Shorr method vs. 0.458 in Pap with CEA IHC method, P=0.987). Conclusions: Shorr staining could be a rapid and reliable method for intraoperative PWC in advanced gastric cancer.