In 1959, the first case of squamous cell carcinoma resulting from an extreme overdosage of grenz rays was described.
(7) Since then, 40 cases have been reported.(8-11) The carcinogenic effect of grenz rays has also been studied in experimental animals.
(12-15) It has been shown that grenz rays can produce metastatic squamous cell carcinoma under certain experimental conditions and that the pattern of tumor development, as in ultraviolet light exposure, was that of carcinogenic summation.
The incidence of carcinoma after grenz-ray therapy is small indeed but may follow extremely high doses in persons who are abnormally sensitive to x rays.(9)