Ionizing radiation and skin cancer - a review of current evidence.

Cancer of the skin represents a challenge for radiological protection, as it is very common and involves the largest organ of the human body, which is exposed to environmental stress, including ionizing radiation. The most common subtypes, basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) have very low mortality. Current consideration of skin cancer in radiological protection is mainly based on data from the 1990s, which indicate that BCC may be induced by ionizing radiation, SCC is only weakly associated with ionizing radiation, and malignant melanoma (MM) is not considered as ionizing radiation-induced. In a semi-systematic review of the evidence between 1990 and 2023, we snowballed 19 index articles. We identified 29 articles with information on a potential dose-response relationship between skin cancer and ionizing radiation exposure and assessed the evidence for a causal association. Exposure situations included a-bomb survivors, therapeutic and occupational exposure (airlines, nuclear and medical facilities) and residents exposed to radon. There is currently no epidemiological evidence that MM or SCC are caused by ionizing radiation. The only skin cancer type with evidence for a causal relationship is BCC, and evidence is limited to exposures above 0.5 Gy with a wide range of risk levels per dose. Thus, ionizing radiation-inducible skin cancer refers to BCC only and only at levels of exposure beyond those experienced by the vast majority of people exposed today.