Sex Disparity in Cancer and Non-cancer Mortality among Korean Cancer Survivors

This study assessed sex disparities in the causes of death (CODs), both related to cancer and non-cancer, in a nationwide database of cancer survivors in South Korea. Our database included cancer cases diagnosed in Korea between 2009 and 2016, and their CODs up to 2021. Deaths were classified into three categories: index-cancer, non-index-cancer, and non-cancer causes. Male-to-female age-standardized mortality ratios (M/F SMRs) were computed by dividing the male-specific mortality rate by the corresponding female-specific rate. Out of a total of 279,104 (49.0%) recorded deaths in male survivors and 141,674 (27.9%) deaths in female survivors, the M/F SMRs showed an elevated mortality risk in males, both for cancer-related causes (1.46, 95% CI 1.45-1.47) and non-cancer CODs (1.75, 95% CI 1.74-1.77). Among non-cancer CODs, the most significant sex disparity in mortality risk was evident in deaths attributed to chronic lower respiratory diseases (CLRDs), with an SMR of 4.51 (95% CI 4.30-4.73), followed by mortalities due to intentional self-harm (suicide) (2.95, 95% CI 2.85-3.05) and transportation accidents (SMR 2.86, 95% CI 2.67-3.04). Subgroup analysis focusing on survivors of common cancer sites indicated a relatively consistent pattern in index cancer deaths, but the M/F SMRs for non-index cancer and non-cancer deaths demonstrated variability across different cancer sites. Our study underscores an overall elevated mortality risk in male cancer survivors compared to female counterparts. Although deaths stemming from primary cancer remain a substantial concern for both sexes, disparities in non-cancer deaths warrant considerable attention, particularly in relation to CLRD and intentional self-harm (suicide) among male survivors.