Higher risk of cardiovascular death than cancer death among long-term cancer survivors

Background Most previous studies have focused more on the short-term risk of cardiovascular death related to traumatic psychological stress after cancer diagnosis, but less on the long-term risk of cardiovascular death. Recent studies suggested that the risk of cardiovascular death would probably outweigh the risk of index cancer death among long-time cancer survivors. However, it has not received enough attention. Methods Temporal trends in the proportions of cardiovascular death (PCV), cancer death (PCA), and other causes in all-cause deaths were used to show preliminary relationships between three causes of death in 4,806,064 cancer patients from the SEER Program. Competing mortality risk curves were used to investigate when cumulative cardiovascular mortality rate (CMRCV) began to outweigh cumulative cancer mortality rate (CMRCA) for cancer patients survived more than 10 years. Competing risk models were used to investigate independent factors associated with cardiovascular death in long-time cancer survivors. Results For all cancer patients, the PCV increased from 22.8% in the 5th year after cancer diagnosis, to 31.0% in 10th year, and 35.7% in the 20th year, while the PCA decreased from 57.7%, to 41.2% and 29.9%, respectively. The PCV outweighed the PCA (34.6% vs. 34.1%) since the 15th year for all cancer patients, as early as the ninth year for colorectal cancer patients (37.5% vs. 33.2%), and as late as the 22nd year for breast cancer patients (33.5% vs. 30.6%). The CMRCV outweighed CMRCA since the 15th year for cancer patients survived more than 10 years, the 5th year for those survived more than 15 years, and the 1st for those survived more than 20 years. Among cancer patients survived more than 20 years, elder age at diagnosis, male, local metastasis, and radiotherapy were associated with increased risk of cardiovascular death, while surgery and chemotherapy were associated with decreased risk of cardiovascular death. Sensitivity analysis by cancer sites showed similar results. Conclusions Cardiovascular death will gradually outweigh cancer death as survival time increases for most cancer patients. Cardio-oncologist should be involved as early as possible in the anti-cancer treatments to reduce cardiovascular death in long-term cancer survivors.