Preoperative thrombocytosis predicts poor survival in patients with glioblastoma

Abstract

Thrombocytosis, which is defined as a platelet count greater than 400 platelets/nl, has been found to be an independent predictor of shorter survival in various tumors. Release of growth factors from tumors has been proposed to increase platelet counts. Preoperative platelet counts and other clinical and hematological parameters were reviewed from the records of 153 patients diagnosed between 1999 and 2004 with histologically confirmed glioblastoma in order to evaluate the prognostic significance of preoperative thrombocytosis in these patients. The relationship between thrombocytosis and survival was initially analyzed in all patients regardless of further therapy. Univariate log-rank tests showed that the median survival time of 29 patients with preoperative thrombocytosis (19%) was significantly shorter (4 months; 95% confidence interval [95% CI], 3-6 months) compared to 124 patients with normal platelet counts (11 months; 95% CI, 8-13 months; p = 0.0006). Multivariate analysis (Cox proportional hazards model) confirmed preoperative platelet count, age, prothrombin time, and activated partial thromboplastin time to be prognostic factors of survival (all p < 0.05). In a subset of patients (only operated patients with radiation therapy with or without additional chemotherapy), survival was likewise significantly shorter when preoperative thrombocytosis was diagnosed (6 months; 95% CI, 4-12 months) compared to patients with normal platelet count (13 months; 95% CI, 11-15 months; p = 0.0359). In multivariate analysis, age, platelet count, preoperative prothrombin time, and degree of tumor resection retained significance as prognostic factors of survival (all p < 0.05). The results of our study demonstrate preoperative thrombocytosis to be a prognostic factor associated with shorter survival time in patients with glioblastoma.

Fig 1

Effect of elevated platelet counts on survival duration in patients with glioblastoma: survival in months (95% confidence interval [95% CI]). (A) Patients with glioblastoma with preoperative thrombocytosis had a statistically significantly shorter overall survival (log-rank test). The composition of the patient groups is described in Table 1. (B) Overall survival of all patients with glioblastoma after creating four strata of platelet counts. Note that patients with platelet counts elevated within the normal range (350–400 platelets/nl) had a significantly reduced survival time compared to patients with a platelet count below 350/nl (p = 0.022). Patients with thrombocytosis below 450 platelets/nl can be expected to have a median survival time of four months (95% CI, 3–5 months) compared to two months (95% CI, 1–4 months) in patients with thrombocytosis greater than 450 platelets/nl (p = 0.057). (C) Overall survival of only patients with complete or incomplete tumor resection and subsequent radiation therapy, with or without additional chemotherapy. The composition of this patient group is described in Table 3.