Suicide, other externally caused injuries, and cardiovascular disease within 2 years after cancer diagnosis: A nationwide population‐based study in Japan (J‐SUPPORT 1902)

BACKGROUND: This study aimed to investigate the risk of death by suicide, other externally caused injuries (ECIs), or cardiovascular disease for patients with cancer. METHODS: We used data from the National Cancer Registry, which include the entire population in Japan. Patients diagnosed with cancer from January 1 to December 31, 2016 were included, and their follow‐up period was set to 2 years. The standardized mortality ratio (SMR) of death by suicide, other ECIs, and cardiovascular disease was calculated compared with the general population. Multivariate Poisson or negative binomial regression analysis was used to quantify the adjusted relative risks of factors of interest. RESULTS: We evaluated 1,070,876 patients with cancer. The 2‐year follow‐up SMR was 1.84 (95% confidence interval [CI]: 1.71–1.99) for suicide, 1.30 (95% CI: 1.24–1.37) for other ECIs, and 1.19 (95% CI: 1.17–1.21) for cardiovascular disease. The SMR was higher with shorter follow‐up periods but was significant 13–24 months after cancer diagnosis. The SMRs at 0–1 month and 13–24 months, respectively, were 4.40 (95% CI: 3.51–5.44) and 1.31 (95% CI: 1.14–1.50) for suicide; 2.27 (95% CI: 1.94–2.63) and 1.27 (95% CI: 1.18–1.37) for other ECIs; and 2.38 (95% CI: 2.27–2.50) and 1.07 (95% CI: 1.04–1.10) for cardiovascular disease. The multivariate analyses showed that patients with cancers other than localized tumors had significantly high relative risks of death for each cause. CONCLUSION: Suicide prevention countermeasures for patients with cancer, especially those with advanced disease immediately after diagnosis, are warranted.