There is a dose-response association between cutaneous squamous cell carcinoma (SCC) risk and lifetime indoor tanning in women, according to study results published in JAMA Dermatology. The association between cumulative indoor tanning exposure and SCC risk was the same regardless of age at initiation and duration of use.

Investigators reviewed data from the Norwegian Women and Cancer study. Patients received baseline questionnaires from 1991 to 2007, with follow-up questionnaires every 5 to 7 years through December 2015. Patients reported pigmentation factors, sunburns, sunbathing vacations, and indoor tanning use in childhood, adolescence, and adulthood. Data analysis was performed from January 2018 to March 2019, resulting in a cohort of 159,419 women born in 1927 through 1963.

In total, 95,552 women (69.0%) reported ever using indoor tanning. During the initial study follow-up period, 597 women were diagnosed with SCC. There was an association between an increased risk for SCC and a higher cumulative number of indoor tanning sessions (hazard ratio [HR], 1.83; 95% CI, 1.38-2.42; highest use vs no use). Compared with patients who had never used indoor tanning, a significantly higher risk for SCC was found in women with >10 years of use (HR, 1.43; 95% CI, 1.16-1.76) and ≤10 years of use (HR, 1.41; 95% CI, 1.08-1.85). An increased risk was seen in women who started to use indoor tanning at 30 years or older (HR, 1.36; 95% CI, 1.11-1.67) and younger than 30 years (HR, 1.51; 95% CI, 1.18-1.92) as well. There was a significant association between an increased SCC risk and increasing number of indoor and outdoor tanning sessions combined (HR, 2.43; 95% CI, 1.74-3.39 for highest vs lowest category; P <.001 for trend). No significant association was found between age at initiation of indoor tanning and age at SCC diagnosis.

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The study was limited by a lack of information about the types of indoor tanning devices or length of sessions, and the use of data from a cohort entirely comprised of women.

“No study, to our knowledge, has prospectively investigated a dose-response

association between lifetime indoor tanning and risk of [SCC],” investigators wrote. “The findings provide supporting evidence that there is a dose-response association between indoor tanning and SCC risk among women. These results support development of policies that regulate indoor tanning,” investigators concluded.

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Reference

Lergenmuller S, Ghiasvand R, Robsahm TE, et al. Association of lifetime indoor tanning and subsequent risk of cutaneous squamous cell carcinoma. JAMA Dermatol. 2019:1-9.

[published online October 2, 2019] doi:10.1001/jamadermatol.2019.2681