Urbanization Inequalities on the Incidence of Intraocular Cancers in Iran: An 11-Year Nationwide Retrospective...

To report the relationship between urbanization and the incidence of intraocular cancers in Iran.

In this retrospective ecological study, data were extracted from the Statistical Center of Iran, the Meteorological Organization, and the Iranian National Population-based Cancer Registry (INPCR, 2006-2016). The urbanization index (UI) was calculated using principal component analysis, and weighted multiple linear regression was used to assess the relationship between the UI and the age-standardized incidence rate (ASIR) of intraocular cancers.

Six hundred and fifty-four intraocular cancer cases with a gender ratio (male-to-female) of 1:13 were recorded. The mean total 11-year ASIR of intraocular cancers was 0.093 per 100,000 population. The mean ASIR showed a decrease of 0.051 per 100,000 from 2006 to 2016 (P = 0.022). Retinoblastoma (66.1%) and uveal melanoma (24.6%) were the most commonly diagnosed intraocular cancers, and their ASIR declined between 2006 and 2016. Once adjusted for environmental pollutants, an increase in the area-based UI was significantly associated with lower total ASIR of intraocular cancers in males ( $\beta$ = -0.14).

Urbanization was associated with a reduction in ASIR of intraocular cancers, which can be attributed to improved access to eye care facilities for timely diagnosis. However, given that the INPCR cases were verified only by histology, future research should be conducted on hospital-based registries using multiple data sources to address confounders and exposure factors and prevent underestimation of incidence rates.