Lack of prognostic role of pre- and postoperative peritoneal cytology and cytokeratin PCR-expression on local recurrence after curative anterior resection for mid-low rectal cancer.

Local recurrence continues to be a major problem in rectal cancer. After cancer removal, detection of viable cancer cells could be useful to identify patients at risk for local recurrence. Thus, aim of the study was the detection of residual peritoneal cancer cells with a possible prognostic role for local recurrence. Twenty-nine patients were operated (R0) for low (extraperitoneal) rectal cancer, without neoadjuvant radiochemotherapy. Before and immediately after cancer removal, a peritoneal lavage was done to evaluate by RT-PCR the cytokeratin 20 mRNA on isolated cells and in order to detect cancer cells by the Thin-prep test. After a median follow-up of 39 months, 5 patients died (17%), one for non-cancer-related disease, two (7%) for local recurrence and peritoneal carcinosis, and two for distant metastases. Preoperative cytology with Thin-prep test was positive in 4 patients (14%), while postoperative peritoneal cytology was positive only in 1 patient, different from the previous. No patient developed local or distal recurrence and all were disease-free at the end of the follow-up. RT-PCR analysis was positive on the peritoneal lavage after cancer removal in 11 patients. One died for unrelated cause and no one developed local recurrences. Local recurrence occurred in only 1 of the 2 patients with positive RT-PCR analysis on the first lavage and negative on the second lavage. Our study demonstrates a not important prognostic role of Thin-prep test and RT-PCR of cytokeratin 20 mRNA on the detection of patients at risk for local recurrence after curative resection of rectal cancer.