Radiation Therapy of Carcinoma of the Skin

Abstract

THE purpose of this paper is to analyze all cases of epithelioma of the skin treated in this Hospital during the past two years, and to review the recent literature on the subject with the objective of determining the optimum technic for curing the largest number of skin carcinomas by the first series of treatments. It is readily seen that the proper treatment of carcinoma of the skin is an important consideration when one realizes there are about four thousand deaths annually in the United States attributed to carcinoma of the skin. It is an established fact that treatment by irradiation produces less scarring than any other method. Since most carcinomas of the skin are on the face, irradiation is the treatment of choice from the standpoint of cosmetic effect. Many people with carcinoma of the skin are reluctant to submit to surgical removal, but will submit to irradiation. The curability of these lesions by irradiation, taken as a whole, is estimated to be from 85 to 95 per cent. At least 85 per cent of all skin carcinomas, and at least 95 per cent of all curable skin carcinomas, can be cured by properly administered irradiation alone. It has long been known (first expressed by Bérgonie and Tribondeau in 1904) that immature cells and cells in the active stage of division are more sensitive to irradiation than are cells which have already acquired their adult or complete morphologic and physiologic characteristics. It is also known that the nucleus is the most sensitive part of the cell, and that the chromatin is the most vulnerable part of the nucleus. Basal cells, having a large amount of chromatin, are, therefore, relatively sensitive to irradiation. Since tumor cells grow more rapidly than normal cells, they are more sensitive to irradiation than are normal cells, and are, therefore, destroyed by smaller doses. The more rapidly growing a tumor is, the more radiosensitive it usually is. There are several exceptions to this rule. Certain malignant melanomas are highly undifferentiated and rapid in growth, but, nevertheless, highly radioresistant. Increased radiosensitivity does not necessarily mean greater radiocurability since the latter involves many other factors, such as metastasis and involvement of bone or cartilage. The more undifferentiated a tumor is, the more likely it is to metastasize early or to infiltrate deeply. Surface radium application, having a continued effect over a long period of time, is superior to x-ray because it is more likely to act on the cells during their active stage of division. It has, however, the disadvantage of rapid decrease in its depth dose, with the danger of not destroying the cells at the base of deep-seated or infiltrating lesions. The time required for radium treatments and the amount of radium available make its wide use impracticable in our Clinic, and these disadvantages probably hold for many other clinics in this country.