Daily use of sunscreen can slow skin aging associated with middle age.
Regular sunscreen use protects against cutaneous squamous cell carcinomas and invasive melanomas, but its effect on cutaneous photoageing has received much less attention, despite a popular preoccupation with ageing and a multibillion dollar industry focused on reversing its effects.
Investigators conducted a randomized, double-blind, controlled trial in 604 subjects younger than 55, most fair-skinned, to evaluate whether regular sunscreen use prevented photoaging of the skin. Approximately half of the participants were randomized to daily application of an SPF15 sunscreen (containing 8% ethylhexyl-p-methoxycinnamate and 2% 4-tert-butyl-4′ methoxy-4-dibenzoylmethane); the other half were given no instructions and applied sunscreen at their own discretion. The groups were similar in skin color and amount of sun exposure. To evaluate photoaging, silicone impressions of the back of the left hand were made at baseline and 4.5 years.
Experienced assessors graded the imprints on a validated scale. After adjustments for differences in sunburn and photoaging of the neck, the daily sunscreen group was 24% less likely to exhibit evidence of progressive photoaging of the skin than those who used sunscreens at their own discretion (relative odds, 0.76; 95% confidence interval, 0.50–0.98). Some patients also received beta carotene, which had no effect on photoaging compared with placebo.
Comment: The findings convincingly demonstrate that regular sunscreen use protects against photoaging, and the beneficial effects can be detected after only 4 years. This effect may persuade individuals more concerned about their appearance than about skin cancer to regularly apply photoprotection. Sunscreens used in this study conducted in the mid-1990s primarily protected against ultraviolet B wavelengths — now, many available products also block UVA, and UVA is known to contribute significantly to photoaging. Therefore, modern broad-spectrum sunscreens may be even more beneficial than the older types used in this study.
— Craig A. Elmets, MD