Purpose: We correlated platelet count to renal tumor characteristics, and evaluated the potential prognostic value of thrombocytosis in localized and metastatic tumors.
Materials and methods: A total of 804 patients operated on for a renal tumor in 2 French centers were included in this study. In all cases TNM stage, Fuhrman grade, tumor size, nodal invasion, ECOG score, histological subtype and platelet count were recorded. Survival estimates were compared with the Kaplan-Meier method and multivariate analysis was performed using a Cox model.
Results: There were 538 (66.9%) males and 266 (33%) females (ratio 2.02) in the patient group. Median age was 62 years. T stages were T1, T2, T3 and T4 in 284 (35.3%), 116 (14.4%), 387 (48.1%) and 17 (2.1%), respectively. There were 112 (13.9%) and 126 (15.7%) patients with nodal and metastatic invasion, respectively. Platelet count was strongly correlated with T stage (p < 0.001), Fuhrman grade (p < 0.001), tumor size (p < 0.001), nodal invasion (p < 0.001) and the presence of distant metastasis (p = 0.01). In univariate analysis all studied factors were significantly predictive of survival (p = 0.0001). Thrombocytosis had an impact on prognosis in localized (p < 0.001) and metastatic (p = 0.003) disease. Several factors were retained in multivariate analysis, namely TNM stage, Fuhrman grade, tumor size, ECOG score and platelet count. In cases with a platelet count of less than 450,000/mm3, the 5-year survival rate was 70%, compared to 38% when the platelet count was 450,000/mm3 or greater.
Conclusions: Platelet count appears to be an independent prognostic factor in renal cell carcinoma. It reflects a cascade of biological events correlated with tumor aggressiveness. This observation opens new perspectives for exploring carcinogenesis mechanisms and tumor progression in renal cell carcinoma.