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Ten-Year Follow-up Showcases Sun-Damaged Skin Associated With Cutaneous Squamous Cell Carcinoma Development

Published in JAMA Dermatology, a recent study argued its results could increase early detection of cutaneous squamous cell carcinoma (cSCC) through development of recommendations within actinic keratosis (AK) treatment. This longitudinal cohort study aimed to identify and estimate the risk of cSCC after the diagnosis of AK up to 10 years since this has not been studied during long follow-up periods.

Performed from January 1, 2009, to February 29, 2020, the authors examined patients with AK and control patients that matched 1:1 on age, sex, race/ethnicity, medical center, and date of the initial diagnosis in addition to the 30 days in the patients with AK. Furthermore, patients with AK and control participants were followed up for up to 10 years for incidence pertaining to cSCC.

They add that incident cSCC was obtained from pathologic data with subdistribution hazard ratios (HRs). Addtionally, 95% CIs were estimated using Cox proportional hazards regression analysis, which accounted for competing risks, calendar year, demographic factors, and number of AKs.

In total, 220,236 patients with AK and 220,236 matched control patients were included; the total mean (SD) age was 64.1 (12.2) years, and  52.5% of patients were female. After adjustments for loss to follow-up, the authors found that the risk of cSCC increased each year of follow-up by 1.92% (95% CI, 1.89%-1.95%) in patients with AK vs 0.83% (95% CI, 0.81%-0.85%) matched controls (subdistribution HR, 1.90; 95% CI, 1.85-1.95). They added that, comparatively, among patients 49 years or younger, those with AK were nearly seven times more likely to be diagnosed with cSCC than those without AK (HR, 6.77; 95% CI, 5.50-8.32).

Further, after 10 years, the cumulative incidence of cSCC reached 17.1% (95% CI, 16.9%-17.4%) in patients with AK and 5.7% (95% CI, 5.5%-5.9%) in control patients. The rising numbers of AKs were associated with increased cSCC risk (≥15 AKs vs 1 AK: subdistribution HR, 1.89; 95% CI, 1.75-2.04). Older patients had much higher risk of cSCC than younger patients (compared with those ≤49 years of age at AK diagnosis; ≥80 years of age: subdistribution HR, 8.18; 95% CI, 7.62-8.78), and, other than AK, risk factors for cSCC included older age, White race (a proxy for skin type), history of basal cell carcinoma, and male sex. Finally, the authors added that risk decreased between 2009 and 2019 (2018-2019 vs 2009-2010: subdistribution HR, 0.67; 95% CI, 0.63-0.72).

“The results of this longitudinal cohort study can be used to develop recommendations to increase early detection of cSCC,” concluded the study authors. They suggested that additional research should be completed to better understand the effect of AK treatment in relation to cSCC risk and its outcomes. –Jessica Garlewicz


Madani S, Marwaha S, Dusendang JR, et al. Ten-year follow-up of persons with sun-damaged skin associated with subsequent development of cutaneous squamous cell carcinoma. JAMA Dermatol. Published online March 24, 2021. doi:10.1001/jamadermatol.2021.0372

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