Sunburns during lifetime, particularly during childhood, tied to increased risk of skin cancer: JAMA

The study also shed light on the importance of sunburns in childhood for the subsequent skin cancer risk. Therefore, it is crucial to avoid sunburns throughout life, particularly in childhood.

Considering that no study has prospectively examined sunburn patterns over aged periods from childhood to adulthood and their associations with the risk of skin cancer, Simon Lergenmuller, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway, and colleagues addressed the question, "What are the life trajectories of sunburns in Norwegian women, and their associations with subsequent risk of cutaneous melanoma and squamous cell carcinoma?"

They aimed to identify lifetime trajectories of sunburns and compare the association between these trajectories and subsequent cutaneous melanoma and squamous cell carcinoma (cSCC) risk.

For this purpose, the researchers conducted a population-based cohort study including participants from the Norwegian Women and Cancer Study, established in 1991, having a follow-up through 2018. The participants were made to fill out questionnaires issued from 1991 to 2007, with follow-up questionnaires every 5 to 7 years.

Participants reported sunbathing vacations, pigmentation factors, and indoor tanning. Annual sunburn frequencies were reported for childhood, adolescence, and adulthood.

The researchers obtained information on emigration, cancer diagnoses, and death through a link to the Cancer Registry of Norway by utilizing the unique personal identification number of Norwegian citizens.

At study inclusion, 169 768 received questions about sunburns from the 172 472 women (age range, 31-70 years) who returned questionnaires.

The study led to the following findings:

• Five classes (stable low, low-moderate-low, low to high, high to low, and stable high) of individual lifetime sunburn trajectories with similar shapes were estimated in 3 samples up to 39 years (n = 159 773), up to 49 years (n = 153 297), and up to 59 years (n = 119 170).
• Mean follow-up ranged from 14.3 to 19.5 years in the three samples, during which 1252 to 1774 women were diagnosed with incident primary melanoma and 739 to 871 women with incident primary cSCC.
• With hazard ratios (HRs) and 95% CIs estimated using a Cox proportional hazards model, the stable high and high-to-low trajectories showed statistically significant increased melanoma and cSCC risks compared with the steady low course across all samples (≤39 years for stable high and high to low trajectories: melanoma: HR, 1.50 and HR, 1.44; cSCC: HR, 1.51 and HR, 1.47).
• Other trajectories showed increased risk, though generally weaker and mainly estimated that were not statistically significant.
• There was no statistically significant heterogeneity between melanoma and cSCC estimates.

"Findings showed that high sunburn frequency throughout life was linked with an increased risk of melanoma and cSCC," the researchers wrote in their study. "Additionally, childhood sunburns are crucial for subsequent risk of these skin cancers."

To conclude, avoiding sunburns throughout life, especially in childhood, is essential.

Reference:

Lergenmuller S, Rueegg CS, Perrier F, et al. Lifetime Sunburn Trajectories and Associated Risks of Cutaneous Melanoma and Squamous Cell Carcinoma Among a Cohort of Norwegian Women. JAMA Dermatol. Published online October 05, 2022. doi:10.1001/jamadermatol.2022.4053