Watts CG, et al. - Authors evaluated the correlates of early-life sunscreen use and the association between sunscreen use and risk of cutaneous melanoma before age 40 years. A significant association of regular sunscreen use with reduced risk of cutaneous melanoma among young adults was suggested in the findings. Several characteristics associated with less sunscreen use were also identified.

Methods

• In this population-based, case-control family study experts evaluated the Australian Melanoma Family Study data for persons with questionnaire data on sunscreen use collected by interview from 2001 to 2005 across 3 states in Australia, representing two-thirds of the country’s population.
• The first primary melanoma was confirmed by the case participants (aged 18-39 years).
• They included the siblings of case participants, and case participants without a sibling control were excluded.
• They recruited the unrelated controls (aged 18-44 years) from the electoral roll or were a spouse, partner, or friend nominated by case participants.
• Researchers conducted a data analyses from October 2017 to February 2018.
• The exposures included the self- and parent-reported sunscreen use, sun exposure, and other candidate risk factors during childhood and adulthood.
• They used the logistic regression analyses adjusted for potential confounders to evaluate the odds ratios (ORs) for melanoma and for correlates of sunscreen use.

Results

• As per data, the participation was 629 of 830 contactable cases (76%) (629 of 1197 overall [53%]), 240 of 570 contactable controls (42%) from the electoral roll (240 of 1068 overall [23%]), and 295 of 371 nominated spouse or friend controls (80%); analysis incuded 603 cases and 1088 controls.
• Findings suggested that 32 (28-36) years for 603 cases was the median (interquartile range) age, 35 (30-38) years for 478 unrelated controls, and 34 (29-38) years for 610 sibling controls.
• In all groups, there were more women than men (range, 57%-62%), approximately 40% (range, 39%-43%) of participants had a university education, and most participants (range, 58%-73%) had British/northern European ethnicity.
• Lower risk of melanoma was less with higher use of sunscreen in childhood (OR for highest vs lowest tertiles, 0.60; 95% CI, 0.42-0.87; P=.02 for trend) and across the lifetime (OR, 0.65; 95% CI, 0.45-0.93;P=.07 for trend).
• There was a stronger protective association of sunscreen with melanoma for people reporting blistering sunburn, receiving a diagnosis of melanoma at a younger age, or having some or many nevi; as seen on subgroup analyses.
• Results demonstrated that total lifetime sun exposure was unrelated to melanoma risk (OR for highest vs lowest tertile, 0.97; 95% CI, 0.66-1.43; P=.94 for trend).
• By contrast, a significant association of total sun exposure inversely weighted by sunscreen use (as a measure of sun exposure unprotected by sunscreen) with melanoma risk (OR, 1.80; 95% CI, 1.22-2.65;P=.007 for trend) and appeared stronger for people having lighter pigmentation or some or many nevi or using sunscreen to stay longer in the sun.
• Results demonstrated a greater likeliness of regular users of sunscreen to be female, younger, and of British or northern European ancestry and to have higher educational levels, lighter skin pigmentation, and a stronger history of blistering sunburn.