[Evaluation of peritoneal cytology in colorectal carcinoma]

We investigated the incidence of free cancer cells in the peritoneal washings of 278 patients who had undergone surgery for colorectal cancer to evaluate its influence as a prognostic factor of the disease. Twenty-two cases (7.9%) were found to have malignant positive cytology (CY(+)). The rate of CY(+) in the cases with peritoneal dissemination (P(+)) was significantly higher than that in P(-) (66.7% vs 3.8%). In 244 cases, those who had tumors exposing to the peritoneum, both CY(+) and P(+) were observed highly in poorly differentiated adenocarcinoma. Among 18 P(+) cases, the rates of CY(+) were higher in both P3 and cur C than in P1, 2 and cur B. When restricted to 260 P(-) cases, CY(+) was observed more often in stage IV cases (14.3% vs 1.8%). Rate was significantly high in M+ (66.7%). Prognosis of 4 P(-) CY(+) cur A cases was as follows; 2 survived for a long time with no recurrence (20 and 60 months), 1 had curable liver metastases after half a year and obtained a 2 year disease free period after surgery, and another one died with brain, liver, and peritoneal recurrence one year later. The incidence of CY(+) is correlated with P(+); CY(+) increased when P(+) is extended more highly and incurable. CY(+) alone doesn't become a prognostic factor for peritoneal recurrences, because CY(+) is found rarely in curable P(-) cases. However, CY(+) is also associated with far advanced cancer with remote metastases, therefore we should consider the risk of such metastases for CY(+) cases with curable colorectal cancer.