Analysis of Competing Risks of Causes of Death in Cancer Patients from Golestan, Iran over Twelve Years (2004-2016)

BACKGROUND: Cancer-related causes of death (cancer CoD) are the main etiologies of death in cancer patients. Recent increase in survival rates of cancer patients resulted in higher risk of dying from causes other than cancer, called competing causes of death (competing CoD). We aim to characterize competing CoD among cancer patients in Golestan province, Northern Iran. METHODS: Data on cancer incidence was obtained from the Golestan population-based cancer registry (GPCR) dataset. Data on causes of death was obtained from the Golestan death registry (GDR) dataset. Using a linkage method between the GPCR and GDR dataset, we prepared the study dataset including data on vital status and causes of death in our cancer patients. The proportions of cancer CoD and competing CoD were calculated. Multivariate logistic regression analysis was considered to assess the relationship between competing CoD and other variables. RESULTS: Overall, 4,184 cancer patients died in the study population, including 2,488 men (59.9%). Cause of death in 3,455 cases was cancer and 729 cases (17.4%) died due to competing CoD. Ischemic heart disease (40.7%) was the most common competing CoD in our population. Higher survival rate was the strongest variable related to the competing CoD (adjusted OR=1.91; 95%CI: 1.61-2.26). Residence area, age group and year of death were other indicators of competing CoD in our population. CONCLUSION: Our results suggest high rates of competing CoD in our cancer patients. Competing CoD should be mentioned in cancer control planning both in clinical practice as well as in public health policy making.