The Prognostic Significance Of Pretreatment Thrombocytosis In Patients With Colorectal Cancer:a Systematic Review And Meta-analysis

Background & aims: Recently,several studies have reported that thrombocytosis may be associated with the poor prognosis of colorectal cancer(CRC).Nevertheless,their conclusions were still controversial.This meta-analysis was designed to analyze and evaluate the prognostic role of preoperative or pretreatment thrombocytosis in patients with colorectal cancer.In addition,the present analysis was also performed to explore the association between thrombocytosis and clinicopathologic characteristics of patients with CRC.Methods: We searched PubMed,Embase,Cochrane Library,Web of Science,CNKI,CBM and WanFang Database to April,2016.The citation lists of included studies were also hand searched to identify further relevant trials.The Hazard Ratio(HR)with its 95% confidence interval(CI)was used to evaluate the relation between overall survival(OS)and thrombocytosis.Likewise,disease free survival(DFS)and cancer specific survival(CSS)was obtained and evaluated.The analysis was performed and assessed using Review Manager 5.2.Results: A total of 30 studies including 9129 patients were included in this systematic review.Of which,24 studies including 6659 patients were counted for incidence of thrombocytosis in colorectal cancer and 1024 patients(16.2%)exhibited pretreatment thrombocytosis.21 studies including 6843 patients were included for meta-analysis(18 studies for OS,10 for DFS and 4 for CSS).Thrombocytosis had a close relationship with the poor OS of colorectal cancer compared with normal platelet counts,with the pooled HRs being 1.89 [95% CI 1.45–2.47;P<0.00001] and 1.83 [95% CI 1.33–2.53;P=0.0002],with univariate and multivariate analyses respectively.For DFS,the same results were found as the pooled HR being 1.47 [95% CI 1.04–2.06;P=0.03] with univariate analysis,but not with multivariate analysis(HR 1.78;95% CI 0.82–3.84;P=0.14).In amazement,significant result was found for CSS,with the pooled HR being 2.06 [95% CI 1.49–2.84;P<0.0001].In addition,the incidence of thrombocytosis had significant association with Gender,Lymph node metastasis,Tumor location,Distant metastasis and Tumor size,but not withAge,Depth of invasion,Differentiation,TNM stage,Responding,lymphatic invasion and vascular invasion.Conclusions: This meta-analysis indicated that thrombocytosis may be a cost-effective and noninvasive indicator for poor prognosis of patients with colorectal cancer,especially for OS.