[Do anticoagulants improve survival in patients with cancer?]

Activation of haemostasis is a key factor for the progression of malignant disease. Experimental data suggest that unfractionated heparin or low molecular weight heparin (LMWH) may reduce tumour progression. LMWH have antiangiogeneic effects and inhibit the binding of cancer cell surface glycosaminoglycans with platelet and endothelial selectins. LMWH also inhibit the degradation of the intercellular matrix by tumour cells. Retrospective analysis of several randomized controlled trials evaluating LMWH in patients with venous thromboembolism suggests that LMWH may reduce cancer related mortality in these patients. More recently, randomized controlled trials have tested this hypothesis in patients with cancer who did not have associated venous thromboembolism with conflicting results. LMWH given at prophylactic dosage in patients with advanced cancer was associated with no or minor survival improvement, although some positive results were obtained with such a regimen in patients with non-small cell lung cancer. On the other hand, it has been shown that LMWH given at a higher dosage was associated with a significant and clinically important improvement on overall survival as compared to placebo in localized cancer. Patients included in those trials had however cancer from different sites and this limit the relevance of these findings. Several trials are under way in order to evaluate different LMWH preparations in patients suffering from the same cancer type. The results will help to confirm or to refute a clinical role of LMWH as adjuvant therapy in patients with cancer.