The First Clinical Medical College of Lanzhou University, Lanzhou, China
Background: Recently, several studies have reported that elevated platelet counts may be associated with the poor prognosis of colorectal cancer. However, conclusions remain controversial. This meta-analysis was therefore designed to analyze and evaluate the prognostic role of preoperative or pretreatment thrombocytosis in patients with colorectal cancer. Materials and Methods: We searched PubMed, EMBASE, the Cochrane Library and Web of Science to March 29th, 2015. The citation lists of included studies were also hand-searched to identify further relevant trials. To investigate the association between thrombocytosis and prognosis of colorectal cancer, the 1-year, 3-year and 5-year survival of each studies were obtained. The odds ratio (OR) with its 95% confidence interval (CI) was used to evaluate the relation of overall survival (OS) between thrombocytosis and normal platelet counts (PLT). Likewise, disease free survival (DFS) was obtained and evaluated. The analysis was performed and assessed using Review Manager 5.2. Results: A total of 14 studies (N5,566 participants, 11 including 4,468 for OS, 6 including 1,533 for DFS) were included in this meta-analysis, of which seven (N3810) defined thrombocytosis as a platelet count 400?109L, and 375 (9.8%) patients exhibited pretreatment thrombocytosis. Thrombocytosis have a close relationship with the poor OS of colorectal cancer compared with normal PLT, with the pooled ORs of 1-year, 3-year and 5-year survival being 0.41 [95% CI 0.34-0.51; P<0.001], 0.28 [95% CI 0.21-0.38; P<0.001] and 0.26 [95% CI 0.20-0.34; P<0.001], respectively. For DFS, the same results were showed as the pooled ORs of 1-year, 3-year and 5-year survival respectively being 0.34 [95% CI 0.24-0.50; P<0.001], 0.31 [95% CI 0.23-0.43; P<0.001] and 0.25 [95% CI 0.18-0.34; P<0.001]. Conclusions: This meta-analysis indicated that thrombocytosis may predict poor prognosis for patients with colorectal cancer, and platelet counts may be a cost-effective and noninvasive marker.