Aims
Cancer and heart failure (HF) share risk factors, pathophysiological mechanisms, and possibly genetics. Improved HF survival may increase the risk of cancer due to a competing risk. Whether the incidence of cancer has increased over time in patients with HF as survival has improved is unclear. Therefore, temporal trends of new onset cancer in HF patients between 1997 and 2016 were investigated.

Methods and results
Using Danish nationwide registers, 103 711 individuals alive, free of cancer, and aged 30–80 years 1 year after HF diagnosis (index date) were included between 1 January 1997 and 31 December 2016. A five-year incidence rate of cancer for each year after index date was calculated. The median age and proportion of women at the index date decreased with advancing calendar time [1997–2001: 70.3 interquartile range (Q1–Q3 62.5–75.7), 60.9% men; 2012–16: 67.6 (59.2–73.8), 67.5% men]. The five-year incidence rate of cancer was 20.9 and 20.2 per 1,000 person-years in 1997 and 2016, respectively. In a multivariable Cox regression model, the hazard rates between index years 1997 (reference) and 2016 were not significantly different [hazard ratio 1.09 (0.97–1.23)]. The five-year absolute risk of cancer did not change with advancing calendar year, going from 9.0% (1997–2001) to 9.0% (2012–16). Five-year cumulative incidence of survival for HF patients increased with advancing calendar year, going from 55.9% (1997–2001) to 74.3% (2012–2016).

Conclusion
Although cancer rates during 1997–2016 have remained stable within 1–6 years after the HF diagnosis, long-term survival following a HF diagnosis has increased significantly.