Diagnostic and prognostic value of peritoneal immunocytology in gastric cancer

Among the clinical factors with a pivotal role in the prediction of outcome for patients with gastric cancer, intraperitoneal (i.p.) microscopic dissemination may represent an important cause of recurrences, even in the early stages of the disease. In this context, the cytologic examination of intraoperative peritoneal washings may be essential to identify metastatic free cells, although a number of false-negative cases may be encountered.

To determine whether immunocytochemical (ICC) methods that used a panel of three monoclonal antibodies (MoAbs), B72.3, AR3, and BD5, directed to gastric cancer-associated antigens can improve peritoneal cytology by providing more accurate prognostic indications, we immunocytochemically and morphologically evaluated 144 peritoneal washings sampled from patients surgically treated for gastric cancer.

The ICC analysis allowed the identification of metastatic free peritoneal cells in 35% of the patients, with a 14% improvement over routine cytopathology (P < .0001). Furthermore, a 54-month survival analysis by Kaplan-Meier curves showed a statistically significant decrease in overall survival (OS) in patients with stages I through III disease with peritoneal microscopic disease detected morphologically and/or by ICC at the time of the primary surgery.

Our data indicate that the use of a combination of selected MoAbs may allow the identification of cytologically false-negative cases that provide valuable prognostic information. This may be useful to stratify patients on more adequate therapeutic trials.