Incidence and prognostic significance of positive peritoneal lavage in colorectal cancer.

PURPOSE: The significance of peritoneal lavage cytology as a prognostic marker has been examined in various types of cancer. However, the meaning of positive peritoneal lavage cytology in colorectal cancer is still controversial. The aim of this review is to evaluate the prognostic significance of positive peritoneal lavage cytology in colorectal cancer.
METHODS: An English literature search was performed on all studies published between 1998 and 2014 that compared the detection of peritoneal free cancer cells with survival or recurrence.
RESULTS: Eighteen articles met the inclusion criteria. All studies employed one (or more) of the three techniques used to detect free cancer cells in the peritoneal cavity: (1) conventional cytology, (2) immunocytochemistry or (3) polymerase chain reaction. The incidence of positive peritoneal lavage cytology ranged from 2.2 to 47.2% across the studies. The factors correlated with positive peritoneal lavage cytology were tumor penetration and metastases (lymph node, liver and peritoneum). In nine studies, positive lavage findings were associated with a worse survival, and it was associated with increased recurrence in 13 studies.
CONCLUSION: Positive peritoneal lavage cytology seems to be an indicator of a poor prognosis in colorectal cancer patients. Further studies are needed to clarify the prognostic impact of peritoneal lavage cytology, by comparing the different methods used for the collection of the peritoneal lavage.