Myocardial infarction and short- or long-term risk of a subsequent cancer diagnosis: A Danish Nationwide Cohort Study

Background: Growing evidence suggests that myocardial infarction (MI) may be a marker of cancer risk, but many aspects of this relation are poorly understood. We therefore examined the short- and long-term risk of incident cancer in patients presenting with MI.

Methods: Using nationwide population-based Danish health registries, we identified all patients with a first-time diagnosis of MI (1995-2021) and followed them for up to 28 years for any subsequent diagnosis of cancer. We computed risks and standardized incidence ratios with 95% confidence intervals (CIs) as the observed number of cancers relative to the expected number based on national cancer incidence rates by sex, age, and calendar year.

Results: Among 185,065 patients diagnosed with MI, we observed 25,315 subsequent cancers. The risk of any cancer was 2.4% after 1 year of follow-up, increasing to 25.8% after 28 years, taking the competing risks of death into account. During the first year of follow-up, the standardized incidence ratio of any cancer was 1.67 (95% CI: 1.62-1.73). The standardized incidence ratio remained moderately elevated during 2-5 years (1.03, 95% CI: 1.01-1.05) and beyond 5 years (1.07, 95% CI: 1.05-1.09). The strongest associations were found for hematological as well as obesity- and smoking-related cancers during the first year of follow-up, whereas primarily the risk of smoking-related cancers remained elevated throughout the entire follow-up period.

Conclusion: MI was associated with subsequent risk of cancer, driven by hematological, obesity- and smoking-related cancers in the short term and smoking-related cancers in the long term.