Empirical Modelling of Cancer Incidence, Mortality and Mortality-to-Incidence Patterns in Iran: A GLOBOCAN 2020 Analysis
Noureddine Ouerfelli *
Institut Supérieur des Technologies Médicales de Tunis, LR13SE07, Laboratoire de Biophysique et Technologies Médicales, Université de Tunis El Manar, Tunis, Tunisia.
Mehrzia Krimi
Université de Tunis El Manar, Laboratoire des Matériaux et de l’Environnement pour le Développement Durable, LR18ES10, 9 Avenue Dr. Zouhaier Essafi 1006 Tunis, Tunisia.
Rania Awadi
Institut Supérieur des Technologies Médicales de Tunis, LR13SE07, Laboratoire de Biophysique et Technologies Médicales, Université de Tunis El Manar, Tunis, Tunisia.
*Author to whom correspondence should be addressed.
Abstract
Background: Site-specific incidence and mortality estimates permit descriptive comparisons of cancer burden, but their association must be interpreted in light of the limitations of ecological and modelled data.
Objective: To characterise the association between estimates of cancer incidence and mortality across 35 cancer sites in Iran in 2020, and to describe site-level mortality-to-incidence and rank-based patterns.
Methods: Published GLOBOCAN 2020 estimates for 35 specified cancer sites were examined using a through-origin linear regression, ordinary least-squares regression of natural-log-transformed counts, and descriptive rank analyses. Mortality-to-incidence ratios (MIRs) were calculated as deaths divided by incident cases in the same calendar year.
Results: GLOBOCAN estimated 131,191 incident cancer cases and 79,136 deaths in Iran in 2020 (national deaths-to-cases ratio, 60.32%). The 35 listed sites accounted for 115,441 cases and 71,290 deaths. The through-origin incidence–mortality slope was 0.6029 (95% confidence interval [CI], 0.508–0.697). The log–log slope was 1.0470 (95% CI, 0.953–1.141; r = 0.9695). The unweighted mean of 35 site-specific MIRs was 56.74%; pancreatic (96.59%), liver (93.39%) and oesophageal (90.67%) cancers had the highest ratios among the selected sites.
Conclusion: The estimates exhibit a positive cross-sectional association between site-specific incidence and mortality counts, with substantial variation in MIR across cancer sites. These in-sample empirical relationships are descriptive, are affected by the estimation of the underlying inputs, and should not be interpreted as patient survival probabilities, causal explanations or validated forecasts.
Keywords: GLOBOCAN 2020, Iran, cancer incidence, cancer mortality, mortality-to-incidence ratio, ecological analysis, regression, cumulative risk