Are Ocular Markers of Sun Exposure Associated With Skin Cancer? A Cross‐Sectional Analysis of the Busselton Healthy Ageing Study

BACKGROUND: Higher past sun or ultraviolet radiation exposure increases the risk of skin cancer and three common ocular findings: pterygium, conjunctival ultraviolet autofluorescence (CUVAF) and myopia. We investigated whether ocular markers of past sun exposure are associated with a history of skin cancer. METHODS: A cross-sectional study of participants who attended the Phase 2 examination of the Busselton Healthy Ageing Study in Western Australia (2016-2022). Myopia was determined from autorefraction and pterygium and CUVAF from photographs of the anterior eye. Past diagnosis of a skin cancer was obtained from linked hospitalisation and cancer registry data (melanoma) or combining linked and self-reported data (keratinocyte cancer). Multivariable logistic regression with multiple imputation was used for analysis. RESULTS: Of 3888 participants who attended, 3829 (98.5%) had skin cancer history data (mean [standard deviation] age 64.2 [5.4] years). A history of keratinocyte cancer was present in 795 (20.8%) participants and cutaneous melanoma in 59 (1.5%) participants. After adjustments, keratinocyte skin cancer was associated with a current pterygium (odds ratio [OR] = 1.33, 95% confidence interval [CI]: 1.05, 1.69) and a previous self-reported pterygium excision (OR = 1.85, 95% CI: 1.21, 2.82). Neither CUVAF or myopia was associated with keratinocyte cancer or melanoma diagnoses. CONCLUSIONS: Having a current pterygium or previous pterygium excision is associated with a diagnosis of keratinocyte skin cancer. While causality cannot be determined, the association may reflect shared risk factors such as chronic ultraviolet radiation exposure, and people with a pterygium should be advised that they are at higher risk of skin cancer.