Thrombocytosis as a prognostic factor for survival in patients with metastatic renal cell carcinoma

Abstract

Background: It has been suggested that thrombocytosis, as defined by a platelet count >400,000/microL, is a negative predictor for survival among patients with metastatic renal cell carcinoma. However, this has not been a uniform finding.

Methods: To address this issue, retrospective analysis of 700 previously untreated patients entering on institution review board-approved phase 1, 2, or 3 clinical trials in the United States and Europe was conducted between 1982 and 2002.

Results: Thrombocytosis was present at study entry in 25% of patients. Median baseline platelet count was 304,000/microL (range, 86-1,420,000/microL). Eighty-seven percent of patients died with a median survival of 13.0 months. Median follow-up for patients not known to have died was 2.4 years. On univariate analysis, patients with elevated platelet counts had significantly shorter survival than patients with normal platelet counts; median survivals of 8.4 and 14.6 months, respectively, P < .001. However, platelet count was associated with several clinical and biochemical factors, including gender, age, performance status, time from diagnosis to study entry, prior radiotherapy or nephrectomy, presence of liver metastasis, number of metastatic sites, amount of hemoglobin, white blood cell count, amount of lactate dehydrogenase, and amount of serum alkaline phosphatase. Several of these factors have previously been reported as prognostic indicators for survival, and, therefore, multivariable analyses were conducted to determine whether thrombocytosis is an independent predictor of survival. After adjusting for multiple factors, thrombocytosis continued to impact negatively on survival, P < .001.

Conclusions: Thrombocytosis was found to be an independent prognostic factor for survival in patients with metastatic renal cell carcinoma.