Isolated tumor cells are frequently detectable in the peritoneal cavity of gastric and colorectal cancer patients and serve as a new prognostic marker

Objective To evaluate the prognostic significance of isolated tumor cells detected by a panel of various monoclonal antibodies, Summary Background Data Previously, we showed by using immunocytology that cancer cells are frequently found in bone marrow and peritoneal cavity samples of gastrointestinal cancer patients. Methods Findings in bone marrow and peritoneal cavity samples were compared and correlated with the 4-year survival rate of 84 gastric and 109 colorectal patients with cancer. Results Although positive results in the bone marrow showed little prognostic significance, the peritoneal cavity results correlated with the 4-year survival rate (gastric cancer: p = 0.0038; colorectal cancer: p = 0.0079). Additionally, in subgroups of patients with early (gastric cancer: p = 0.02, colorectal cancer: p = 0.48) and advanced (gastric cancer: p = 0.02, colorectal cancer: p < 0.0001) tumor stages, a correlation of immunocytologic findings and the survival rate was seen. Conclusions The detection of minimal residual disease in the peritoneal cavity serves as a new prognostic marker.