National and subnational burden of female and male breast cancer and risk factors in Iran from 1990 to 2019: results from the Global Burden of Disease study 2019.

Background: Breast cancer (BC) is one of the most burdensome cancers worldwide. Despite advancements in diagnostic and treatment modalities, developing countries are still dealing with increasing burdens and existing disparities. This study provides estimates of BC burden and associated risk factors in Iran at the national and subnational levels over 30 years (1990-2019).

Methods: Data on BC burden for Iran were retrieved from the Global Burden of Disease (GBD) study from 1990 to 2019. GBD estimation methods were applied to explore BC incidence, prevalence, deaths, disability-adjusted life years (DALYs), and attributable burden to risk factors based on the GBD risk factors hierarchy. Moreover, decomposition analysis was performed to find the contribution of population growth, aging, and cause-specific incidence in the total incidence change. Age-standardized rates (per 100,000 population) and 95% uncertainty intervals (UI) were reported based on sex, age, and socio-demographic index (SDI).

Results: Age-standardized incidence rate (ASIR) increased from 18.8 (95% UI 15.3-24.1)/100,000 in 2019 to 34.0 (30.7-37.9)/100,000 in 2019 among females and from 0.2/100,000 (0.2-0.3) to 0.3/100,000 (0.3-0.4) among males. Age-standardized deaths rate (ASDR) increased slightly among females from 10.3 (8.2-13.6)/100,000 in 1990 to 11.9 (10.8-13.1)/100,000 in 2019 and remained almost the same among males-0.2/100,000 (0.1-0.2). Age-standardized DALYs rate also increased from 320.2 (265.4-405.4) to 368.7 (336.7-404.3) among females but decreased slightly in males from 4.5 (3.5-5.8) to 4.0 (3.5-4.5). Of the 417.6% increase in total incident cases from 1990-2019, 240.7% was related to cause-specific incidence. In both genders, the BC burden increased by age, including age groups under 50 before routine screening programs, and by SDI levels; the high and high-middle SDI regions had the highest BC burden in Iran. Based on the GBD risk factors hierarchy, high fasting plasma glucose (FPG) and alcohol were estimated to have the most and the least attributed DALYs for BC among females, respectively.

Conclusions: BC burden increased from 1990 to 2019 in both genders, and considerable discrepancies were found among different provinces and SDI quintiles in Iran. These increasing trends appeared to be associated with social and economic developments and changes in demographic factors. Improvements in registry systems and diagnostic capacities were also probably responsible for these growing trends. Raising general awareness and improving screening programs, early detection measures, and equitable access to healthcare systems might be the initial steps to tackle the increasing trends.