The exfoliation of free malignant cells in the peritoneal cavity during resection of colorectal cancer.

The presence of free malignant cells in the peritoneal cavity following potentially curative resection of colorectal cancer may be responsible for some cases of local recurrence. Twenty-six patients (age 58-88 years, male:female 12:14) undergoing colorectal cancer surgery were studied to determine frequency of occurrence of tumour cells in the peritoneal cavity using an immuno-magnetic cell separation technique. Peritoneal washings were collected after opening the peritoneal cavity and also prior to closure. A murine monoclonal antibody specific for epithelial cells was added to the peritoneal washings followed by magnetic labelled goat-antimouse antibody. The labelled tumour cells were retrieved by passing through the magnetic activated cell sorter (MACS). Tumour cells were detected in peritoneal washings from 11 patients (preresection only n = 0, post-resection only n = 6, and both n = 5). Five of these 11 patients had potentially curative surgery. This study supports the use of MACS in detecting free malignant cells in the peritoneal cavity.