Poor prognosis associated with thrombocytosis in patients with renal cell carcinoma.

To better define the relationship between platelet count and survival using a retrospective analysis in patients with thrombocytosis and metastatic renal cell carcinoma (RCC), some of whom had a shorter life expectancy than those with a normal platelet count. The records were reviewed of patients with stage IV RCC who had undergone a variety of adjuvant therapies after nephrectomy between 1972 and 1992. Entry criteria included a tissue diagnosis of RCC, at least one platelet count and a complete follow-up until the time of death. Of 350 patients available for review, 259 met the entry criteria. Patients were divided into two groups: group 1 included 112 patients whose platelet counts remained at < 4 x 105/microL between the time of nephrectomy and the time of death; group 2 included 147 patients with at least one platelet count of > 4 x 105/microL (mean age in each group 57 years). The mean (SD) survival for group 1 was 151 (34) months, compared with 92 (18) months for those in group 2. Using the log-rank chi-square test the difference in survival between the groups was significant (P = 0.005). Controlling for established prognostic indicators of pathological stage, nuclear grade and cell type, using Cox's regression technique, the difference in survival between the groups remained significant (P = 0.015). These results suggest that patients with metastatic RCC who receive adjuvant therapy and have a persistently normal platelet count have a 64% longer life expectancy than those with thrombocytosis. The difference is highly statistically significant when controlled for nuclear grade, cell type and pathological stage.