The clinicopathological and prognostic role of thrombocytosis in patients with cancer: A meta-analysis.

Previous studies have linked the presence of thrombocytosis with the progression and development of cancer; however, this trend requires further investigation. The present study aimed to derive an estimation of the degree of association between thrombocytosis and the 5-year overall survival rate of patients with cancer, as well as common clinicopathological features, by performing a meta-analysis of 20 (n=12,778) published studies. The PubMed and Embase databases were searched systematically for all relevant articles published in English. Odds ratios (ORs) with 95% confidence intervals (CI) were calculated using a fixed effects or random effects model to evaluate the degree of the observed associations. The results suggested that thrombocytosis (platelet count, >400×109/l) correlated with a decreased 5-year overall survival rate (OR=2.70, 95% CI=2.03-3.61) and an advanced tumor-node-metastasis stage (III + IV; OR=2.14, 95% CI=1.58-2.90). Furthermore, these associations remained robust following stratification of the data by cancer type and ethnicity. In addition, thrombocytosis (platelet count, >300×109/l) correlated with a decreased 5-year overall survival rate in patients with colorectal cancer (OR=3.49, 95% CI=1.44-8.46). Although certain biases were not able to be eliminated, the present meta-analysis suggested that thrombocytosis is a valuable indicator for the evaluation of pathological diagnosis and prognosis for patients with cancer. Further studies are required to investigate the effect of thrombocytosis on the prognosis of patients with cancer.