There is no convincing evidence that aspirin or NSAIDs are effective as chemopreventive agents for keratinocyte cancers.

In an analysis of data from 34,630 Queenslanders in the QSkin Sun and Health Study, there were only inconsistent patterns of association between prior use of the drugs and subsequent risk of BCCs or SCCs.

At baseline, participants aged 40-69 years self-reported medication use in the previous year, sun exposure and skin cancer history. Using linkages to Medicare data on skin cancer treatments, the study followed participants for a median of three years.

It identified 3,421 BCCs and 1,470 SCCs during the study period. The age-standardised incidence rate of BCC and SCC was 2,843 and 1,012 per 100,000 person years, respectively.

In participants who were categorised as at high risk for skin cancer based on a history of at least one skin cancer excision or more than five actinic lesions treated, the study found no association between aspirin use and incidence of BCC.

There was however a modest inverse association between infrequent or frequent use of NSAIDs and BCC (HR 0.92 and 0.84 respectively).

There was no association between frequent use of aspirin and SCC (HR 1.07) but an inverse association between infrequent aspirin use and SCC (HR 0.77).

The study found no association between NSAIDs used and subsequent SCCs.

Neither aspirin nor NSAIDs had any discernible effect on the occurrence of BCC and SCC in participants deemed to be at low to average risk of skin cancer, the study said.

“Overall, we observed weak and inconsistent inverse associations between use of these medications and incidence of either BCC or SCC.”

“The effect sizes we observed are compatible with those from systematic reviews; statistically significant inverse associations were mostly observed among participants deemed at high risk rather than in general population cohorts.”

The researchers noted this was possibly the best available evidence given that randomised controlled trials were unlikely due to the uncertain benefit and potentially adverse effects from the medications.