Neonatal mice do not have increased sensitivity to induction of squamous cell carcinomas.
BACKGROUND
Squamous cell carcinoma (SCC) is linked with the lifelong cumulative effect of ultraviolet radiation (UVR). In contrast, epidemiological data have shown that sunburn in childhood is a stronger risk factor for cutaneous malignant melanoma than continuous UVR, indicating a higher carcinogenic sensitivity early in life.


METHODS
We investigated how a high neonatal dose of UVR affects the development of SCC in mice irradiated later in life. We used simulated solar radiation (sun) and solarium radiation (solarium). Ninety-nine C3.Cg/TifBomTac-immunocompetent hairless mice received 0, 25 or 35 standard erythema doses (SED) UVR when they were 4 days old followed by 4 SED sun or 4 SED solarium three times/weekly from 9 weeks of age.


RESULTS
Tumours developed faster in mice treated with 35 SED UVR + 4 SED sun compared with 4 SED sun, but no change was observed in the cumulative dose required to achieve tumours. Tumours also developed faster in mice treated with 35 SED UVR + 4 SED solarium compared with 4 SED solarium, and a difference was also observed in the cumulative dose required to achieve tumours. If the Skin Cancer Utrecht-Philadelphia-murine spectrum was used to weigh the delivered irradiance instead of the International Commission on Illumination erythema action spectrum, tumours developed after the same accumulated dose.


CONCLUSIONS
In conclusion, this study does not indicate increased sensitivity to induction of SCC early in life.
Department of Dermatology, Copenhagen University Hospital, Bispebjerg, Denmark. cler0001@bbh.regionh.dk
Catharina M
CM
Lerche
Thomas
T
Poulsen
Hans Christian
HC
Wulf
D000367:Age Factors; D000375:Aging / Q000276:immunology / Q000473:pathology*; D000818:Animals; D000831:Animals, Newborn; D002294:Carcinoma, Squamous Cell / Q000276:immunology / Q000473:pathology*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D008297:Male; D051379:Mice; D009381:Neoplasms, Radiation-Induced / Q000276:immunology / Q000473:pathology*; D012307:Risk Factors; D012878:Skin Neoplasms / Q000276:immunology / Q000473:pathology*; D013997:Time Factors; D014466:Ultraviolet Rays / Q000009:adverse effects*