Mortality risk after cancer-related venous thromboembolism has decreased over the last three decades: the HUNT and Tromsø studies

Venous thromboembolism (VTE) is a common and serious condition among cancer patients. The diagnostic and therapeutic strategies for cancer and VTE have improved during the last three decades. It remains unclear whether mortality after cancer-related VTE (CRVTE) has decreased in this period. Therefore, we investigated the mortality risk after CRVTE over the last three decades in a population-based cohort. In total, 111,119 participants from Tromsø4-7 (1994-2016) and HUNT2-3 (1995-2008) surveys were followed through 2019, and all first-lifetime cancer and VTE events were recorded. CRVTE patients were compared with participants neither exposed to cancer nor VTE (disease-free group), and those with cancer. We estimated hazard ratios (HR) with 95% confidence intervals (CI) for all-cause mortality using Cox regression with cancer and VTE as time-dependent exposures, and 1-year cumulative incidence of mortality after CRVTE. Analyses were performed for three time periods: 1994-2002, 2003-2011, and 2012-2019. The age- and sex-adjusted HR for mortality after CRVTE versus disease-free group decreased from 25.3 (95% CI: 20.5-31.3) in 1994-2002 to 22.6 (95% CI: 19.2-26.6) in 2003-2011, and 16.9 (95% CI: 14.3-20.0) in 2012-2019. The HR for mortality after CRVTE versus cancer group remained stable (approx. 3-fold higher) along the three time periods. Similar estimates were obtained after further adjustments for comorbidities. The 1-year cumulative incidence of mortality after CRVTE decreased from 61.8% (95% CI: 52.9-70.8%) in 1994-2002 to 55.6% (95% CI: 49.0-62.4%) in 2003-2011, and 45.5% (95% CI: 39.3-52.1%) in 2012-2019. Our results indicate a decrease in mortality risk after CRVTE over the last three decades, which might be mainly the result of considerable advances in cancer management.