High sunburn frequency throughout life and a high-to-low trajectory are associated with an increased risk for cutaneous melanoma and squamous cell carcinoma (cSCC), according to a study published online Oct. 5 in JAMA Dermatology .

Simon Lergenmuller, M.D., from the Cancer Registry of Norway in Oslo, and colleagues examined the lifetime trajectories of sunburns and compared the association between these trajectories and the subsequent risk for cutaneous melanoma and cSCC in a population-based cohort, established in 1991 with follow-up through 2018. Baseline questionnaires were administered in 1991 to 2007; follow-up questionnaires were completed every five to seven years.

Of the 172,472 women who returned questionnaires, 169,768 completed questions about sunburns at study inclusion. The researchers identified five classes of individual lifetime sunburn trajectories (stable low, low-moderate-low, low-to-high, high-to-low, and stable high) in three samples up to 39 years, 49 years, and 59 years (159,773, 153,297, and 119,170 women, respectively). In the three samples, mean follow-up ranged from 14.3 to 19.5 years, during which 1,252 to 1,774 and 739 to 871 women were diagnosed with incident primary melanoma and cSCC, respectively. Compared with the stable low trajectory, the stable high and high-to-low trajectories showed statistically significant increased melanoma and cSCC risks across all samples (melanoma: hazard ratios, 1.50 and 1.44; cSCC: hazard ratios, 1.51 and 1.47, respectively, for up to 39 years).

"Importantly, the present results suggest that childhood is a more susceptible phase with regard to sunburns and subsequent risk of these skin cancers. It is therefore crucial to emphasize the importance of avoiding sunburns throughout life, and in particular in childhood," the authors write.

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