Serosal cytologic study to determine free mesothelial penetration of intraperitoneal colon cancer

Background. The presence of complete transmural penetration with tumor cells at the free mesothelial surface in patients with intraperitoneal colon cancer is an important prognostic feature and may alter the decision regarding adjuvant chemotherapy. Methods. In this prospective study of 65 patients, specimens obtained by scraping the serosa overlying the primary tumor mass were analyzed by routine Papani‐colaou cytologic study. Results. Malignant cells were present in 23.1% of patients. In 46 patients with histologic pT3 tumors through the muscularis propria but not through serosal, serosal cytologic study results were positive in 26.1% of patients. Serosal cytologic results were positive from an area of normal colon at least 10 cm proximal or distal to the primary tumor in one patient. Conclusions. Serosal cytologic study appeared to be a simple and reliable method to detect serosal penetration and the presence of tumor cells at the mesothelial surface. Cancer 1992; 70:737–740.