title: X-rays and photocarcinogenesis in hairless mice.
abstract: It is well known that excessive X-ray radiation can cause non-melanoma skin cancers. With the increased incidence of sun-related skin cancer there is a need to investigate the combination of sunlight and X-rays. Immunocompetent C3.Cg/TifBomTac mice (n = 298) were divided into 12 groups. Mice were irradiated with 12, 29 or 50 kV X-rays. The mice received a total dose of 45 Gy. They were irradiated with 3 SED simulated solar radiation (SSR) either before or after irradiation with X-rays. The groups irradiated with X-rays alone, 0, 3, 9 and 10 mice (0, 12, 29 and 50 kV, respectively) developed squamous cell carcinoma. In the groups irradiated with SSR after X-rays the development of tumours was significantly faster in the 50 kV group than in the corresponding control group (175 vs. 194 days, p < 0.001). In the groups irradiated with SSR prior to the X-ray radiation the development of tumours was significantly faster in the 29 and the 50 kV groups than in the corresponding control group (175 vs. 202 days, p < 0.001 and 158 vs. 202 days, p < 0.001, respectively). In conclusion, X-ray radiation alone is a weak carcinogen in hairless mice. There is an added carcinogenic effect if X-ray radiation is given on prior sun-exposed skin or if the skin is sun-exposed after X-rays. We still believe that X-ray radiation is a safe and effective therapy for various dermatological diseases but caution should be observed if a patient has severely sun-damaged skin or has a high-risk sun behaviour.
authors.affiliation: Department of Dermatology, D92, Copenhagen University Hospital, Bispebjerg, Bispebjerg Bakke 23, 2400, Copenhagen, NV, Denmark. catharina.margrethe.lerche@regionh.dk
authors.forename: Catharina M
authors.initials: CM
authors.lastname: Lerche
authors.forename: Peter A
authors.initials: PA
authors.lastname: Philipsen
authors.forename: Hans Christian
authors.initials: HC
authors.lastname: Wulf
mesh_terms: D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000209:etiology* / Q000473:pathology; D002471:Cell Transformation, Neoplastic / Q000473:pathology; D004195:Disease Models, Animal; D005260:Female; D051379:Mice; D008812:Mice, Hairless; D009381:Neoplasms, Radiation-Induced / Q000209:etiology* / Q000473:pathology; D011829:Radiation Dosage; D018570:Risk Assessment; D012307:Risk Factors; D012878:Skin Neoplasms / Q000209:etiology* / Q000473:pathology; D013472:Sunlight / Q000009:adverse effects*; D013997:Time Factors; D047368:Tumor Burden; D014466:Ultraviolet Rays / Q000009:adverse effects*; D014965:X-Rays / Q000009:adverse effects*