Background: Thrombocytosis in patients with cancer has been reported to be associated with increased expression of angiogenic factors and with a poor prognosis in some types of cancer. The aim of this study is to analyze the clinicopathologic significance and prognostic value of platelet counts in patients with esophageal cancer.
Study design: Platelet counts were measured before surgery in 374 patients diagnosed between 1987 and 1999 with primary esophageal squamous cell carcinoma. We used the cut-off level of 293 x 10(9)/L (mean of 80 healthy controls +/- standard deviation) to define thrombocytosis. We analyzed the relationship between platelet counts, TNM factors, and white blood cell counts. Among 374 patients, the levels of C-reactive protein were analyzed in 170 patients and serum thymidine phosphorylase concentration was analyzed in 91 patients. The multivariate prognostic value of platelet counts, tumor size, and TNM factors were determined using Cox's proportional hazards model.
Results: Platelet counts were significantly increased in patients with large tumors (p < 0.001), deep tumors, nodal involvement, and distant metastasis in univariate analysis. C-reactive protein level, white blood cell count, and serum thymidine phosphorylase concentration were also significantly increased in patients analyzed with thrombocytosis in univariate analysis. Adjusting for tumor size and TNM factors, multivariate analysis indicated that thrombocytosis as defined in this study was an independent prognostic factor (hazard ratio = 1.52, 95% CI = 1.11 to 2.08, p = 0.009).
Conclusions: A high platelet count is associated with tumor progression and poor survival in patients with esophageal carcinoma.