The efficacy and safety of low-molecular-weight heparin use for cancer treatment: a meta-analysis

Low-molecular-weight heparin (LMWH) has an anti-tumour effect in-vitro and in animal models of malignancy; however, the evidence from clinical trials is controversial. Thus, we performed a meta-analysis from the results of randomised controlled trials (RCTs) to assess LMWH efficacy and safety in cancer patients who had no venous thromboembolism (VTE).

We searched the MEDLINE, EMBASE and CENTRAL (The Cochrane Central Register of Controlled Trails) databases covering all papers published up until April 2012. Two reviewers (D. H. Che and J. Y. Cao) extracted the data independently. The inclusion criteria used were patients with cancer who had no VTE and were treated with LMWH. The outcomes of interest included the 1-year mortality rate, VTE, bleeding and major bleeding complications. The results were presented as a relative risk (RR), and the STATA 11.0 package was used for comprehensive quantitative analysis.

A total of 11 studies with 3835 cases and 3449 controls were included. The meta-analysis showed significant differences in the rates of bleeding with an RR: 1.32 [95% confidence interval (95% CI, 1.08-1.62)] and VTE with an RR: 0.53 (95% CI, 0.42-0.67) in cancer patients when LMWH was compared with placebo or no anticoagulant. There were no significant differences in the 1-year mortality rate with an RR: 0.97 (95% CI, 0.92-1.02) and major bleeding with an RR: 1.22 (95% CI, 0.87-1.71).

LMWH does not significantly reduce the 1-year mortality rate for cancer patients. Although LMWH can prevent VTE, we should consider the risk-effect ratio (in case of an increased bleeding event) when we use LMWH in the patients with cancer. Thus, further research is still needed to confirm these results.