Factor V 1691 G-A (Leiden) polymorphism and cancer-related venous thromboembolism: a meta-analysis of published studies.

PURPOSE

Although one of the most common genetic polymorphisms that predispose to venous thromboembolism (VTE) is factor V 1691 G-A (Factor V Leiden; FVL), the effect of this polymorphism on the development of VTE in cancer patients is unclear. We have therefore performed a meta-analysis to estimate the risk of VTE associated with FVL among cancer patients.

MATERIALS AND METHODS

Relevant studies published before May 2006 were retrieved from Pubmed/Medline. We selected studies comparing the prevalence of FVL in cancer patients with VTE with cancer patients without VTE. Both fixed and random effect models were used. P-values and odds ratios (ORs) with 95% confidence intervals (95% CI) were calculated by Fisher's exact test.

RESULTS

Pooled results from 9 studies, comprising 397 cancer patients with VTE and 678 cancer patients without VTE revealed that the prevalence of FVL was higher among cancer patients with VTE (7.3%) than those without VTE (4.6%) (chi(2) = 34.633 > chi(2) (18; 0.05) =28.869) (p=0.013). It was also found that mean effect size of FVL was 0.22 (95% CI 0.051-0.4892). Using the homogeneity test, there was evidence of statistical heterogeneity (Q(hom)= 46.334> chi(2) (8; 0.05) =15.507) (p=0.0000).

CONCLUSION

Although the published studies were small and the meta-analysis demonstrated an association of FVL with cancer-related thrombosis, testing for FVL can be routinely used as part of clinical thrombophilia assessment in cancer patients from the regions with high incidence of FVL.