Radiation therapy is the use of focused, high energy beams of X-rays, photons, or electrons to treat cancer. In fact, the mycosis fungoides variant of cutaneous T-cell lymphoma (CTCL) may have been the first type of cancer treated with radiation therapy after X-rays were discovered at the end of the 19th century. Today, radiation therapy is used to treat individual CTCL lesions (local or spot treatment) or the entire skin surface (total skin).
There are different types of radiation suitable for treatment of the skin, with low orthovoltage X-ray and electron beam most commonly used. Electron beam therapy is most frequently used, as it delivers radiation primarily to the layers of involved skin and spares the deeper tissues and organs of radiation effects. Orthovoltage X-ray therapy is still employed for treatment of isolated skin tumors or ulcerated plaques that are thicker, or that don’t respond to other treatments.
CTCL is highly radiosensitive, meaning that radiation therapy is very effective (with cure rates near 100%) for the lesions that are treated. Radiation therapy may be used alone for patients with single lesions of CTCL, but is often used in conjunction with other systemic treatments. Radiation treatments are usually administered in a divided or “fractionated” way, meaning that patients receive small doses on subsequent days to reduce the side effects and maximize the benefit. The effects of radiation therapy build up over time, and the full impact may not be seen until after the treatment is completed.
Side effects of local radiation therapy are dependent on the dose of radiation used, and at very low doses radiotherapy to the skin can have essentially no side effects. At higher doses, side effects can include erythema (redness), desquamation (peeling), atrophy (skin thinning), and skin dryness.
Total skin electron beam (TSEBT) is a technique of delivering electron beam radiation to the entire skin surface, and is a very effective treatment for those with widespread lesions. Traditionally, higher doses of radiation were used, however, most centers now use low dose (12 Gy) TSEBT for CTCL with lower side effects. Low-dose TSEBT is still very effective, with more than three quarters of patients getting a good response.
TSEBT is typically administered over a 6-10-week period. Patients receiving TSEBT stand in different positions during the course of therapy to make sure the entire body is treated. Contact lenses, goggles, and shields for the finger and toe nail plates are placed prior to radiation exposure to ensure protection to these important structures. Patients are assessed at weekly intervals for findings of redness, swelling, blisters and infection. In some instances, treatment schedules may be interrupted for short recovery periods. Common side effects can include hair loss, nail loss, skin peeling, and itching. Patients are instructed throughout the course of TSEBT, and for a period of time thereafter, to keep the skin well-hydrated with moisturizers, apply UVA/UVB blocking sun screens, wear sunglasses, and consider photo-protective garments for outdoor exposures.