Risk factors for peritoneal dissemination of colorectal cancer

Background and Objectives: The aim of this study was to clarify the risk factors associated with positive peritoneal dissemination (PPD) of colorectal cancer (CRC). Methods: From June 2000 to September 2002, 143 CRC patients who underwent elective curative (79.0%) or non-curative (21.0%) open laparotomy were prospectively studied. Clinical evaluations including classical factors, colonoscopic evaluation, intraoperative evaluation, and pathological features were recorded. PPD was diagnosed when macro- (MAPD) or microscopic peritoneal dissemination (MIPD) was evident. Positive peritoneal cytology from initially existing ascites or washing lavage indicated MIPD. Various factors were analyzed with univariate (Chi-square test) and then multivariate analyses (logistic regression test) to search for the risk factors of PPD. Results: Overall, MIPD, MAPD, and PPD were found in 2.8%, 6.3%, and 9.1%, respectively. Univariate analysis identified age (≤59 years), CA19-9 (≥34.6 U/ml), poor differentiation, circumferential involvement (≥3 quadrants), ascites volume (>80 ml), pN+, and pT4 as risk factors of PPD. PPD did not occur in patients with well-differentiated tumors, less circumferential involvement (<2 quadrants), or no lymph node metastasis. After multivariate analysis, CA19-9 (Odds ratio (95% CI), 8.6 (1.7-43.1)), pT4 (9.0 (1.3-61.0)), and age (5.26 (1.1-25.0)) remained significant risk factors. Conclusion: CA19-9 (≥34.6 U/ml), pT4, and age (≤59 years) were significant risk factors of PPD.