(HealthDay News) — Use of a sun protection factor (SPF) 15 lotion is associated with a 10-fold reduction in the incidence of melanocytic nevi in a laboratory opossum model, according to an experimental study published online in Pigment Cell & Melanoma Research.

Hareesh B. Nair, MD, from the Texas Biomedical Research Institute in San Antonio, and colleagues examined the preventive characteristics of a moisturizing lotion with SPF 15 compared to a lotion without SPF in a Monodelphis domestica model that resembles ultraviolet B (UVB)-induced melanoma in humans.

A total of 174 opossum pups were used as controls (radiation only; group 1); 289 pups were coated with lotion without SPF (group 2); and 325 pups were coated with lotion containing SPF 15 (group 3). In groups 2 and 3, the lotions were applied to the dorsal side between the limbs 30 minutes before irradiation.

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The pups were exposed to nine sub-erythemal doses of 175 J/m² of UVB radiation, administered on alternate days.

The researchers found that the frequency of animals with nevi did not differ significantly in groups 1 and 2 (8.0% and 5.5%, respectively; P = 0.288). In group 3, the frequency of affected animals was significantly reduced compared with groups 1 and 2 combined (0.6% vs. 6.5%; P < 0.001).

Use of SPF 15 sunscreen correlated with a 10-fold reduction in the incidence of melanocytic nevi.

“The data reinforce the notion that human melanoma can be largely prevented by the judicious use of sunscreens with SPF 15 or higher,” the researchers wrote.

“We speculate that young children may be especially vulnerable to UVB-induced melanoma. We encourage parents to be cognizant of the importance of application of sunscreen with SPF 15 or higher on every occasion that a child is going to be exposed to sunlight,” they conclude.


  1. Nair HB, Ford A, Dick EJ Jr, Hill RH Jr, et al. Modeling sunscreen mediated melanoma prevention in the laboratory opossum (Monodelphis domestica). Pigment Cell Melanoma Res. 2014;doi:10.1111/pcmr.12283.