Background: Venous thromboembolism (VTE) frequently complicates cancer. Data on tumour-specific VTE predictors are limited, but may inform strategies to prevent thrombosis.
Methods: We computed incidence rates (IRs) with 95% confidence intervals (CIs) for VTE hospitalisation in a cohort of cancer patients (n=57,591) and in a comparison general-population cohort (n=287,476) in Denmark. The subjects entered the study in 1997-2005, and the follow-up continued through 2006. Using Cox proportional-hazards regression, we estimated relative risks (RRs) for VTE predictors, while adjusting for comorbidity.
Results: Throughout the follow-up, VTE IR was higher among the cancer patients (IR=8.0, 95% CI=7.6-8.5) than the general population (IR=4.7, 95% CI=4.3-5.1), particularly in the first year after cancer diagnosis (IR=15.0, 95% CI=13.8-16.2, vs IR=8.6, 95% CI=7.6-9.9). Incidence rates of VTE were highest in patients with pancreas (IR=40.9, 95% CI=29.5-56.7), brain (IR=17.7, 95% CI=11.3-27.8) or liver (IR=20.4, 95% CI=9.2-45.3) tumours, multiple myeloma (IR=22.6, 95% CI=15.4-33.2) and among patients with advanced-stage cancers (IR=27.7, 95% CI=24.0-32.0) or those who received chemotherapy or no/symptomatic treatment. The adjusted RR (aRR) for VTE was highest among patients with pancreas (aRR=16.3, 95% CI=8.1-32.6) or brain cancer (aRR=19.8 95% CI=7.1-55.2), multiple myeloma (aRR=46.1, 95% CI=13.1-162.0) and among patients receiving chemotherapy, either alone (aRR=18.5, 95% CI=11.9-28.7) or in combination treatments (aRR=16.2, 95% CI=12.0-21.7).
Conclusions: Risk of VTE is higher among cancer patients than in the general population. Predictors of VTE include recency of cancer diagnosis, cancer site, stage and the type of cancer-directed treatment.