With great interest, we read the article by Landthaler et al,1 who discuss the late carcinogenic effects of soft x-rays (10 to 50 kV) applied to human skin. The retrospective analysis, performed on 522 patients with long-term follow-up after radiation therapy of their cutaneous tumors, showed secondary malignancies inside the exposed fields, with a low incidence of 3.5%. No relationship was found between the total dose applied, ranging from 20 Gy (single dose) to 184 Gy (fractionated), and the latency and frequency of radiogenic tumors. Histopathologically, these tumors were classified as basal cell carcinomas (2%) and squamous cell carcinomas (1.5%).
In our laboratory, quantitative data were obtained on carcinogenic effects of fractionated irradiation of rat skin.2 The skin was exposed locally to 200-kV x-ray doses of 60 to 82 Gy in 30 or 35 fractions in 6 weeks, conforming to clinical radiotherapy regimens. Independent of the total dose
Sminia P, Carl UM. Secondary Tumors After X-ray Radiation Therapy of the Skin. Arch Dermatol. 1995;131(9):1088. doi:10.1001/archderm.1995.01690210120024