Impact of Preoperative Thrombocytosis on the Survival of Patients with Primary Colorectal Cancer

Although thrombocytosis has been reported in patients with various types of cancer, the association between thrombocytosis and the clinicopathological features of patients with colorectal cancer (CRC) has not been fully investigated. We evaluated the clinical features associated with thrombocytosis in CRC. The medical records of 636 consecutive CRC patients undergoing surgery in our department between January 2002 and July 2008 were retrospectively reviewed. The correlation between the clinicopathological variables and the preoperative platelet count was analyzed by univariate and multivariate analyses. The impact of thrombocytosis on the prognosis of these patients was assessed, in comparison with the other clinicopathological variables. Platelet count showed significant correlation with gender, age, venous involvement, tumor size, depth of invasion, regional lymph node metastasis, distant metastasis in univariate analysis, and tumor size and depth of invasion were independent factors in multivariate analysis. The cancer-specific survival (CSS) of CRC patients with thrombocytosis was significantly shorter than that for those without thrombocytosis (P < 0.001), specifically in patients with stage III CRC (P < 0.001). Multivariate analysis indicated that thrombocytosis was an independent prognostic factor of CSS (hazard ratio = 2.96, 95% confidence interval [CI] = 1.72-5.00). Moreover, within stage II CRC, the univariate analysis revealed that disease-free survival (DFS) was associated with preoperative thrombocytosis, but not the other clinicopathological variables. Preoperative thrombocytosis is not only an independent indicator of poor CSS in CRC patients but also an independent predictor of poor DFS in patients with stage II CRC.