Cardiac surgery and long-term risk for incident cancer: A nationwide population-based study

Objective: Previous studies indicate an increased long-term risk for incident cancer and cancer-specific mortality in patients undergoing cardiac surgery. We compared the risk for incident cancer and cancer-specific mortality between patients and matched control subjects from the general population. Methods: All patients (n = 127,119) undergoing first-time coronary artery or heart valve surgery in Sweden during 1997-2020 were included in a population-based observational cohort study based on individual data from the SWEDEHEART registry and 4 other mandatory national registries. The patients were compared with an age-, sex-, and place of residence–matched control population (n = 415,287) using multivariable Cox proportional hazards regression models adjusted for baseline characteristics, comorbidities, and socioeconomic factors. A propensity score–matched analysis with 81,522 well-balanced pairs was also performed. Results: Median follow-up was 9.2 (range, 0-24) years. A total of 31,361/127,119 patients (24.7%) and 102,959/415,287 control subjects (24.8%) developed cancer during follow-up. The crude event rates were 2.75 and 2.83 per 100 person-years, respectively. The adjusted risk for cancer and cancer-specific mortality was lower in patients (adjusted hazard ratios 0.86 [95% CI, 0.85-0.88] and 0.64 [95% CI, 0.62-0.65], respectively). The propensity score–matched analysis showed similar results (hazard ratios, 0.88 [95% CI, 0.86-0.90] and 0.65 [95% CI, 0.63-0.68], respectively). The results were consistent in subgroups based on sex, age, and comorbidities. Conclusions: Patients who underwent cardiac surgery have lower risk for cancer and cancer-specific mortality than matched control subjects.