Wound care after radiation therapy

Advances in Skin & Wound Care, Sep/Oct 2002 by Mendelsohn, Felicia A, Divino, Celia M, Kerstein, Ernane D

ABSTRACT

More than 50% of all cancer patients receive some form of radiotherapy for tumor control preoperatively, postoperatively, or as sole treatment. Radiation-induced wounds are a concern for patients and practitioners. Current research investigating alternative treatment strategies offers the hope of improved wound healing and enhanced quality of life for patients with these wounds. This paper reviews the pathophysiology of wounds following radiation treatment, the methods for treating radiation-induced wounds, and experimental treatment strategies that have been investigated.

ADV SKIN WOUND CARE 2002;15:216,218-24.

Radiotherapy has evolved as a powerful tool for tumor control preoperatively, postoperatively, or as a sole treatment. More than 50% of cancer patients receive some form of radiation treatment and, despite improvements in radiation techniques, patients are still experiencing radiation-induced injury.

The term radiation injury refers to the morphologic and functional changes that can occur in noncancerous tissue as a direct result of ionizing radiation. These complications can range from mild to extremely debilitating or life-threatening.'

Ionizing radiation causes damage to tissue by means of energy transference. This energy generates highly reactive chemical products such as free ion radicals. The free radicals can subsequently combine with normal body chemicals and react with cellular components, ultimately causing intracellular and molecular damage. The primary targets of damage are cellular and nuclear membranes and deoxyribonucleic acid (DNA).

The susceptibility of an individual cell to radiation damage is directly proportional to its ability to divide. The most sensitive cells are those which divide rapidly, such as cells of the skin, bone marrow, and gastrointestinal tract.2 In addition to sensitivity of the exposed cell, morbidity from radiation depends on the dose received, time over which the dose is received, volume of tissue irradiated, and quality or type of radiation.3 Additional information on radiation therapy can be found in Radiation Therapy Techniques.

EFFECTS OF RADIATION THERAPY

Morphologic changes

Histologically, morphologic changes can be seen in the cell after radiation exposure. With low doses of radiation, changes occur mainly in the nucleus. Under the microscope, clumping of the nuclear chromatin and swelling of the nucleus can be seen. With higher doses of radiation, the cell nucleus often becomes dense and disfigured and there may be loss of the nuclear membrane. The cytoplasm may show swelling, the mitochondria may be distorted, and the endoplasmic reticulum may degenerate.3 Cellular changes resulting from low-dose radiation are probably due to an apoptotic mechanism, whereas changes related to high-dose radiation are probably due to direct cellular necrosis.

Acute effects

Direct effects of radiation can be divided into immediate, acute (days to weeks), and delayed (months to years). Acute effects result from necrosis of the rapidly proliferating cell lines. A transient, faint erythema may appear during the first week of treatment due to dilatation of capillaries and may be associated with an increase in vascular permeability. Radiation inhibits mitotic activity in the germinal cells of the epidermis, hair follicles, and sebaceous glands. Epilation and dryness of the skin occur.

By the third or fourth week of radiation, typical erythema is localized to the radiation field and the skin is noticeably red, edematous, warm, and tender. Larger vessels, such as arterioles, may be obstructed by fibrin thrombi, edema is prominent, and there may be small foci of hemorrhage. Cellular exudate is rare.

Dry versus moist desquamation

If the total radiation dose to the skin does not exceed approximately 30 gray (Gy, the measure of radiation dose), the erythema phase is followed during the fourth or fifth week by a dry desquamation phase, characterized by pruritus, scaling, and an increase in melanin pigmentation in the basal layer. Within 2 months, inflammatory exudate and edema have subsided, leaving an area of brown pigmentation.

If the total radiation dose to the skin is 40 Gy or greater, the erythema phase is followed by a moist desquamation phase. This stage usually begins in the fourth week and is often accompanied by considerable discomfort. Bullous formation occurs suprabasally and sometimes subepidermally. Eventually, the roofs of the bullae are shed and the entire epidermis may be lost in portions of the irradiated area. Edema and fibrinous exudate persist. In the absence of infection, reepithelization of the denuded skin usually begins within 10 days. Ulcers may appear at any time from approximately 2 weeks after radiation exposure. Ulcers formed in the early stage are a result of direct necrosis of the epidermis; these ulcers usually heal but tend to recur.3,4

Long-term effects

Approximately 1 year after radiation treatment, the epidermis is thin, dry, and semitranslucent, with vessels easily seen. Hair follicles and sebaceous glands are usually absent. Some sweat glands may also have been destroyed. In time, increasing fibrosis of the skin is present. Much of the collagen and subcutaneous adipose tissue are replaced by atypical fibroblasts and dense fibrous tissue that may cause induration of the skin and may limit movement. In radiation injury of soft tissue, fibrinous exudate accumulates under the epidermis.