History of cancer and survival after coronary artery bypass grafting: Experiences from the SWEDEHEART registry

Objective: To explore the currently unknown association between history of cancer at the time of coronary artery bypass grafting (CABG) and long-term survival.

Methods: All patients (n = 82,137) undergoing isolated first-time CABG in Sweden during 1997-2015 were included in this retrospective population-based cohort study. Individual patient data from the SWEDEHEART registry and 4 other mandatory nationwide health care registries were merged. Multivariable Cox proportional hazards regression and competing risk models adjusted for age and gender were used to assess associations between history of cancer, and long-term all-cause, cardiovascular and cancer mortality. Median follow-up was 9.0 years (interquartile range, 4.8-13.1).

Results: Altogether, 6819 (8.3%) of the patients had a history of cancer. The annual prevalence increased from 3.8% in 1997 to 14.8% in 2015. Patients with a history of cancer were older (72 vs 66 years; P < .001) and had more comorbidities. Long-term all-cause mortality was significantly greater in patients with a history of cancer (45.7% vs 22.9% at 10 years; adjusted hazard ratio, 1.33; 95% confidence interval [CI], 1.28-1.38, P < .001). According to the competing risk models, history of cancer was associated with an increased risk for cancer death (subdistribution hazard ratio, 2.45; 95% CI, 2.28-2.63, P < .001) but not cardiovascular death (subdistribution hazard ratio, 0.88; 95% CI, 0.83-0.94, P < .001).

Conclusions: The proportion of patients undergoing CABG with a history of cancer has increased over time. History of cancer at the time of surgery is associated with increased cancer deaths over time but not cardiovascular deaths. The same cardiovascular prognosis after CABG can be expected regardless of cancer history.