Australian skin cancer incidence is extremely high, particularly in older Australians, many of whom take multiple medications for comorbidities. Whether these medications influence development of skin cancers is of importance, to improve risk management.
The ASPREE study comprised a randomised double-blind clinical trial (100mg aspirin versus placebo) between 2010-2017 (median 4.7 years follow up), and an observational phase, (2 years), and tracked all cancer events as a secondary outcome. A Cox proportional hazards regression analysis related time to first keratinocyte carcinoma (KC) or melanoma, to medication use at study entry (self-reported/linkage with the Pharmaceutical Benefits Scheme), adjusting for age, sex, race, previous melanoma or cancer. Medication effect on development of multiple primary KC required recurrent event analysis (Anderson Gill model; AG).
Immunosuppressive medication was associated with increased risk of KC development (adjHR 1.58, 95% CI: 1.27 to 1.97, p<0.001) but not with melanoma (adjHR 1.17 (0.37, 3.64), p=0.79) or the rate of multiple KC development (AG adjHR 1.12 (0.91, 1.37), p=0.30).
NSAID was associated with reduced rate of KC development (AG adjHR 0.93 (0.86, 1.00), p=0.05), however, aspirin was not.
Photosensitizing medication corresponded with an increased rate of KC development (AG adjHR 1.15 (1.03, 1.28), p=0.011), but no increased risk of KC (adjHR 1.05 (0.93, 1.19), p=0.43) or melanoma (adjHR 0.71 (0.35, 1.43), p=0.33).
In conclusion, our study showed that medications can influence KC incidence, however, most had little effect on melanoma, highlighting a need for nuanced understanding when prescribing medications for older Australians at risk of KC.