Radiation therapy (or radiotherapy) is a key component of cancer treatment and palliation for a wide variety of cancers. Radiotherapy works by delivering ionizing radiation to tumors, which damages critical cellular structures and ultimately results in the death of malignant cells. While highly effective at limiting tumor growth, the damaging effects of radiation also pose a threat to surrounding normal tissues.
Radiodermatitis is one of the most common adverse effects of radiation therapy. More severe skin manifestations can significantly impact patient quality of life and can even result in interruptions in therapy that can impact long-term outcomes (Lazarev, Adv Radiat Oncol, 2018; Bese, Oncology, 2005). Though preventative and symptomatic therapies exist to combat the symptoms of radiodermatitis, more effective therapies are needed to improve the patient experience.
Radiodermatitis collectively refers to a constellation of skin reactions that largely develop in a dose- and time-dependent manner following radiotherapy. Acute manifestations, by definition, occur within 90 days of radiation exposure, while chronic manifestations occur months to years following cessation of therapy.
In an acute reaction, mild reddening of the affected area (or erythema) is usually the first symptom to develop and can be seen after the first dose of radiation (Bray, Dermatol Ther (Heidelb), 2016). With ongoing treatment, erythema may persist or worsen, and itching (pruritis), burning, and edema may develop around days 10-14. By weeks 3 or 4, desquamation reactions can occur. Desquamation is an inflammatory response to radiation that leads to flaking or sloughing of the skin with or without associated serous drainage (termed moist and dry desquamation, respectively).
Dry desquamation may appear after a lower total radiation dose and is typically less bothersome than moist desquamation, which is often painful and distressful to patients (Fuzissaki, J Pain Symptom Manage, 2019). Moist desquamation initially presents in the skin folds or creases, where skin tension and friction are greatest, but can ultimately spread to involve contiguous areas of skin. The most severe skin reactions involve full thickness ulceration and necrosis of the skin, which can be life-threatening due to severe electrolyte disturbances and deficits in thermoregulation.
Besides the most severe cases, skin reactions can resolve within 4 – 8 weeks of cessation of radiotherapy with appropriate preventative and therapeutic strategies. However, grades 2 and above carry an increased risk of superimposed infection, typically with Staph aureas, that can delay wound healing (Altoparlak, Eurasian J Med, 2011). Given the potentially devastating nature of grade 4 lesions, outcomes tend to vary greatly from person-to-person.
In addition to medical complications that can arise, skin lesions can also substantially impact patient quality of life during the treatment period, with patients citing pain, pruritis, disturbed body image, and emotional distress as key contributors to dissatisfaction. The negative patient experience can result in treatment interruptions and even premature cessation of therapy, both of which can negatively impact overall survival and other clinical outcomes (Lazarev, Adv Radiat Oncol, 2018; Bese, Oncology, 2005).