The critical role of peritoneal cytology in the staging of gastric cancer: an evidence-based review.

Positive peritoneal cytology (Cyt+) is an important staging tool for patients with locally advanced gastric cancer. The objective of this review is to evaluate the current literature regarding cytology evaluation in patients with gastric cancer and to provide recommendations on the inclusion of this powerful prognosticator in patients with this disease. A literature search was performed for recent and pertinent studies evaluating peritoneal cytology in patients with gastric adenocarcinoma. Peritoneal cytology as the only evidence for M1 disease is present in up to 10% of patients with locally advanced gastric cancer; survival in the setting of Cyt+ is dismal when gastrectomy is the first line of therapy. Improved survival is associated with response to chemotherapy indicated by conversion to negative cytology, good performance status, and antral tumors. Highly select patients with Cyt+ treated with gastrectomy show improved survival in only some of the available studies. There are high quality studies that support the routine practice of peritoneal cytology evaluation in patients with locally advanced gastric cancer. The role of gastrectomy remains unclear in patients with Cyt+ and clinical trials are needed to define the best treatment option for this select group of patients.