Side Effects of Radiation Treatment

Abstract

Depending on the total dose, the following acute changes may occur during radiotherapy or up to 90 days after its initiation: dry skin, epilation, erythema, moist desquamation, erosion, or ulceration. The more severe reactions moist desquamation, erosion, and ulceration have not to be expected after total doses below 45 Gy, unless they are caused by the tumor itself. Typical changes may appear in irradiated fields months to years after superficial radiotherapy: depigmentation, often associated with atrophy, telangiectases, hyperpigmentation, depressed scars, erythema, induration, and keratoses. These changes have been termed chronic radiodermatitis or roentgenoderm. The threshold dose for late visible radiation sequelae is lower than the dose usually required for the treatment of malignant tumors, with the exception of some malignant lymphomas. Permanent hair loss in the irradiated field has to be expected after treatment of cutaneous malignant tumors. Visible radiation sequelae may have cosmetic importance. Patients usually accept the cosmetic outcome if they have been carefully informed about side effects prior to treatment. Pruritus or burning may occur in irradiated areas but in most cases only temporarily. Irradiation around the eye can cause epiphora which usually does not permanently trouble the patient. After radiotherapy of lip carcinomas, the occlusion of the mouth may be insufficient with the consequence that fluid runs out of the mouth when eating or drinking. This may be caused by the destructive growth of the tumor before radiotherapy and has been more frequently observed after surgery compared to radiotherapy. Typical microscopic changes of chronic radiodermatitis are atrophy of the epidermis and sweat glands, absence of hair follicles and sebaceous glands, dilation of superficial blood vessels, fibrosis, elastosis and giant multinucleate fibrocytes. Radiogenic ulcers are caused by an insufficient supply of nutrients and oxygen in the irradiated field. In most cases, they can be cured by ointments and moist compresses. The connective tissue changes found in chronic radiodermatitis are caused by overproduction and deposition of extracellular matrix that is regulated by cytokines, particularly tumor growth factor β-1 (TGF-β1). To compare the therapeutic results from different studies and therapeutic modalities, uniform criteria have to be used for the assessment of acute and late effects. The Radiation Therapy Oncology Group (RTOG) has, in collaboration with the European Organization for Research and Treatment of Cancer (EORTC), developed the LENT (late effects normal tissue) SOMA scoring system which can be used to document subjective, objective, management, and analytic information for 38 anatomic sites including skin and subcutaneous tissue. Irradiation of children for ringworm of the scalp (tinea capitis) has significantly increased the risk to develop a basal cell carcinoma after relatively long latency periods. Ultraviolet light is a cofactor for the development of these basal cell carcinomas. The risk of radiation induced skin cancer increases with time from exposure. In most studies, the skin cancer risk was not significantly elevated after exposure of adults to small radiation doses. We assume that the skin cancer risk after radiotherapy for a malignant cutaneous neoplasm is low because (1) radiation fields are small; (2) high doses applied in a short time interval kill cells, and dead cells cannot become neoplastic; and (3) the life expectancy of the usually relatively old patients who are treated for a cutaneous malignancy is in most cases shorter than the latency period for the induction of a malignant tumor.