Long-term risk for incident cancer in patients undergoing coronary artery bypass grafting with or without cardiopulmonary bypass: a nationwide population-based study

OBJECTIVES: It has been suggested that long-term risk for incident cancer is increased in patients operated with cardiopulmonary bypass. We compared the risk for incident cancer and cancer-specific death between patients undergoing coronary artery bypass grafting (CABG) with and without cardiopulmonary bypass. METHODS: All patients without a history of cancer undergoing first-time CABG in Sweden during 1997-2020 were included in a nationwide population-based observational cohort study. Individual patient data from the SWEDEHEART registry and 4 other mandatory national registries were merged. The incidence of new cancer was compared between patients operated with or without cardiopulmonary bypass using multivariable Cox proportional hazards regression models adjusted for baseline characteristics, co-morbidities, socioeconomic factors and time of surgery. A propensity score-matched analysis with 3735 well-balanced pairs was also performed. RESULTS: A total of 81 097 patients undergoing CABG with (n = 77 345) and without cardiopulmonary bypass (n = 3752) were included. Median follow-up was 8.2 (interquartile range 4.0-13.2) years. The crude event rates were 2.71 and 2.68 per 100 person-years in the patients operated with and without cardiopulmonary bypass, respectively. There was no difference in the adjusted risk for cancer between the groups [adjusted hazard ratio 0.95 (95% confidence interval; CI 0.90-1.01)] or in the risk for cancer-specific death between the groups [adjusted hazard ratio 0.99 (95% CI 0.89-1.09)]. The propensity score-matched analysis showed similar results [hazard ratio 0.96 (95% CI 0.89-1.04) and 0.99 (95% CI 0.85-1.13)], respectively. CONCLUSIONS: Cardiopulmonary bypass is not associated with an increased risk of incident cancer or cancer-specific mortality in patients undergoing CABG.