Intraperitoneal-Free Cancer Cells Represent a Major Prognostic Factor in Colorectal Peritoneal Carcinomatosis

BACKGROUND: Intraperitoneal-free cancer cells are considered as an important prognostic tool in gastric and ovarian cancer. However, their significance in colorectal cancer remains more controversial. OBJECTIVE: This study aimed to determine the role of intraperitoneal-free cancer cells as a prognostic tool in the outcome in colorectal peritoneal carcinomatosis treated with curative intent by complete cytoreductive surgery. DESIGN: This study is an analysis of a prospectively maintained database. PATIENTS: Between 1991 and 2012, all patients treated in a single institution for colorectal peritoneal carcinomatosis by complete cytoreductive surgery with peritoneal cytology available were evaluated. Peritoneal cytology was stained in the conventional way (May Grumwald Giemsa). RESULTS: Among a population of 162 patients treated for colorectal peritoneal carcinomatosis by complete cytoreductive surgery, 38 presented positive intraperitoneal-free cancer cells (23.5%). Systemic chemotherapy was administered to 135 patients (85%) during the preoperative course. Median follow-up was 34.5 months. Median overall survival was 19 and 44 months for positive and negative intraperitoneal-free cancer cells (p = 0.018). In multivariate analysis, Peritoneal Carcinomatosis Index and positive intraperitoneal-free cancer cells were significant prognostic factors of overall survival (HR, 2.3 (1.18-4.52), p = 0.014; HR, 1.9 (1.08-3.38), p = 0.027). LIMITATIONS: Retrospective analysis and the long period were limitations of study. CONCLUSION: Along with the Peritoneal Carcinomatosis Index, intraperitoneal-free cancer cells are a strong prognostic factor for patients treated with curative intent for colorectal peritoneal carcinomatosis by complete cytoreductive surgery. The presence of intraperitonealfree cancer cells should lead to the consideration of different treatment strategies such as extensive intraperitoneal lavage, targeted intraperitoneal therapies, or repeated intraperitoneal chemotherapy.