Visual Impairment and Cancer Risk: A Nationwide Cohort Study of Adult Swedish Men and Women

Background: Visual impairment is linked to a broad spectrum of health conditions. Nevertheless, there is an absence of large cohort studies investigating cancer risk in the visually impaired compared to seeing controls. The aim of this study was to investigate whether visually impaired adults have an increased risk for various types of cancer, compared to seeing controls. Methods: This was a retrospective cohort study comparing visually impaired adults aged 40 and over and 1:5 matched controls (by sex, birth year, and county of residence), between 2002 and 2018. Data were extracted from the Swedish National patient Registry, Statistics Sweden and from the Swedish Cause of Death Registry. A total of 48,493 adult Swedish men (44%) and women (56%), with a median age of 77 years (IQR: 64-86), with various degrees of visual impairment, from mild to total blindness, and 242,465 matched controls were followed up for a median of 5.1 (IQR 2.9-8.6) and 6.0 (IQR 3.6-9.8) years, respectively. The main outcomes included overall cancer incidence and incidence of different types of cancer. Results: Data analysis showed that visually impaired adults had an 18% significantly increased risk of any cancer (HR 1.18, 95% CI 1.16-1.20) when compared to seeing controls. The risk was also significantly increased for most cancers, with HRs ranging from 2.59 (95% CI 2.21-3.03) for brain cancer to 1.19 (95% CI 1.11-1.27) for breast cancer. No interaction was observed between cancer of any type and sex (p = 0.47). An elevated risk for all cancers in the visually impaired was observed across all age-groups: HR of 1.37 (95% CI 1.30-1.43) for ages 40-64, HR 1.17 (95% CI 1.13-1.20) for ages 65-79, and HR 1.11 (95% CI 1.08-1.15) for ages over 80. The risk of death was 60% higher among the cases compared to controls (HR 1.60, 95% CI 1.58-1.63). Conclusions: In this retrospective study of older adults, visual impairment was associated with increased cancer risk both overall and for specific types of cancer, in both sexes and across different age divisions of the cohort. These findings indicate the need for adjustments in health care polices in order to ensure equity in medical services.