Immunocytology improves prognostic impact of peritoneal tumour cell detection compared to conventional cytology in gastric cancer

Aims: Studies on the;value of peritoneal tumour cell dissemination for prog nosis in gastric cancer using various methods to detect tumour cells have p roduced conflicting conclusions. We studied the incidence and prognostic re levance of microscopic intraperitoneal tumour cell dissemination in gastric cancer, comparing conventional and immunocytological detection. Methods: Peritoneal wash-outs of 111 consecutive gastric patients without o vert peritoneal carcinomatosis, including 75 curatively resected patients, were studied. Sixty patients with benign disorders served as controls. 100 ml of warm NaCl 0.9% was instilled intraoperatively and 20 ml was reaspirat ed. The specimens were stained peri-operatively with H&E. In the last 47 pa tients (30 of whom were curatively resected) additional immunostaining with the HEA-125 antibody was performed. The results of cytology were correlate d with the TNM categories and with post-operative follow-up. Results: Of the patients, 42.3% and 48.9% were positive when conventional a nd immunocytological staining were employed, respectively. Conventional cyt ology was significantly associated with the pT and M categories. Immunocyto logy was significantly associated with the pT, pN and M caterogies. In four of 30 curatively resected patients (13.3%), the results of conventional an d immunocytology were different. Three patients with positive immunocytolog y but negative conventional cytology died during follow-up (median follow-u p 45.3 months), whereas one patient with positive conventional but negative immunocytology is still alive. In an univariate analysis 4 years post-surg ery, positive immunocytology was significantly associated with an unfavoura ble prognosis in patients with curatively resected gastric cancer. While on ly 28.6% (six of 21) of the patients with negative immunocytology had died, this proportion increased to 77.8% (seven of nine) with positive immunocyt ology (P = 0.018). The mean survival of negative vs positive patients amoun ted to 1205+/-91 vs 772+/-147 days (P = 0.007). In contrast, in conventiona l cytology we found no significantly different survival time between negati ve and positive patients. Conclusions: Immunocytology seems to be superior to conventional cytology a nd should be preferred.