The risk of venous thromboembolism is increased throughout the course of malignant glioma - An evidence-based review

BACKGROUND. Venous thromboembolism (VTE) frequently complicates the course of patients with cancer, and there is evidence to suggest that patients wit h brain tumors are at particularly high risk. The objective of this methodo logy-based literature review was to quantify the rate of incidence of VTE i n patients with malignant glioma and to determine the factors that predict an increased risk of this complication. METHODS. Studies meeting predefined inclusion criteria were evaluated indep endently on an eight-item methodology index by three raters. Authors were c ontacted to reserve ambiguities. The results of the studies were summarized and the incidence rate of VTE within the early postoperative phase and dur ing extended follow-up were reported separately. RESULTS. Within 6 weeks after surgery the incidence rate of deep venous thr ombosis (DVT) ranged from 3% to 60%, varying with the prophylaxis regimen u sed, the method of diagnosis, and the study design. Beyond 6 weeks postoper atively, the rates of DVT ranged from 0.013 to 0.023 per patient-month of f ollow-up. The single study with no significant methodologic deficiencies fo und a 24% rate of incidence of symptomatic DVT over the 17 months of follow -up beyond the first 6 postoperative weeks. In 6 studies the presence of le g paresis, histologic diagnosis of glioblastoma multiform, age greater than or equal to 60 years, large tumor size, use of chemotherapy, and length of surgery > 4 hours were identified as possible risk factors. CONCLUSIONS. The incidence of VTE is high throughout the course of malignan t glioma. A randomized, controlled trial is needed to clarify whether the b enefits of long term anticoagulant prophylaxis outweigh the risks and costs of such therapy. (C) 2000 American Cancer Society.