Venous thromboembolism in five-year cancer survivors: a nationwide cohort study

Background Cancer is associated with a significant short-term risk of venous thromboembolism (VTE), a condition associated with significant morbidity and mortality. The development of novel cancer therapies and diagnostic modalities has improved survival for patients with cancer, resulting in a growing population of long-term cancer survivors. Concern has been raised that there might be an increased risk of VTE in long-term cancer survivors. Purpose We investigated the long-term risk of VTE in five-year cancer survivors according to cancer subtype, age, and sex compared with a matched background population. Methods Using Danish nationwide registries, we matched five-year survivors of 21 cancers (>18 years; diagnosed 2000-2017; and included 2005-2022 [five years after cancer diagnosis]) with individuals from the background population. We performed a 1:1 matching for the overall population and 1:4 matching for each cancer subtype. Rates of VTE were examined with Cox regression models overall and according to age and sex for the overall population and for cancer subtypes. Results In the overall population, 222,297 five-year cancer survivors were matched with 222,297 individuals from the background population (median age 69.2 years; 43.6% males). During a median follow-up of 5.6 years, cancer survivors had a higher associated rate of VTE compared with the background population (adjusted hazard ratio [aHR] 1.85 [95% CI, 1.78-1.93]). Survivors of all 21 cancer subtypes had a higher associated rate of VTE compared with the background population, with the highest incidence rates found for multiple myeloma. HRs were higher in younger cancer survivors compared with older cancer survivors (<50 years: aHR, 2.85 [95% CI, 2.33-3.47]; 50-64 years: aHR, 2.26 [95% CI, 2.07-2.46]; >65 years: aHR, 1.69 [95% CI, 1.61-1.77]; Pinteraction<0.0001). Similar HRs were found in females and males (females: aHR 1.84 [95% CI, 1.75-1.95]; males: aHR 1.86 [95% CI, 1.75-1.98]; Pinteraction=0.94). See Figure for results. Conclusions In this nationwide cohort study, five-year cancer survivors had a higher associated rate of VTE compared with a matched background population overall and across 21 cancer subtypes. The highest incidence rates were found for multiple myeloma. As the population of long-term cancer survivors continues to grow, implementing strategies to reduce and manage risk factors for VTE becomes increasingly important. Our findings provide important insights into the cardiovascular risk profile of cancer survivors and may guide the development of evidence-based screening and prevention strategies in this population.