LOCAL & TOTAL SKIN ELECTRON BEAM CONVENTIONAL RADIATION THERAPY

Radiation therapy uses X-rays and electrons to treat the skin. In fact, the mycosis fungoides variant of cutaneous T-cell lymphoma (CTCL) may have been the first type of cancer treated with radiation therapy only a few years after X-rays were discovered at the end of the 19th century.  Today, radiation therapy can be used to treat individual CTCL lesions (local) or the entire skin surface (total skin). 

Types of  X-rays suitable for treatment of the skin include low orthovoltage X-ray and electron beam is also used. Orthovoltage X-ray can effectively treat recurrent lesions, but its penetration to underlying tissues (blood vessels, muscles, bone marrow) can prove to be a distinct disadvantage if more widespread disease is evident.  In contrast to conventional X-rays, electron beam therapy delivers radiation primarily to the layers of involved skin and spares the deeper tissues and organs any radiation effects. 

In current CTCL care, local x-ray therapy is employed for treatment of isolated skin tumors or ulcerated plaques that don’t respond to other treatments.  Orthovoltage X-ray therapy has been gradually replaced by electron beam treatment in many centers.

Electron Beam Therapy

Electron beam effectively penetrates the superficial portions of the skin (epidermis and dermis).  Thus, electron beam therapy (EBT) is extremely effective in clearing most problematic skin manifestations of CTCL.  

EBT is delivered by experienced radiation oncologists in collaboration with dermatologists and oncologists specializing in the treatment of CTCL.  

Total Skin Electron Beam Therapy

Over the past fifty years, total skin electron beam therapy (TSEBT) has undergone multiple modifications with the goal of delivering a sufficient dose to the target tissue while minimizing radiation damage to normal skin. The premise for electron therapy in CTCL is to produce direct toxicity to tumor cells within the target volume.

Candidates for TSEBT are those patients who have extensive skin involvement of their CTCL lesions or have exhausted other conventional skin-directed therapies such as topicals and phototherapy. The depth of penetration for electrons is quite minimal, approximating only 5mm; therefore, radiation effects are produced only as deep as the dermal skin layer.

TSEBT is typically administered over a 9-10-week period. Patients receiving TSEBT assume six standing positions during the course of therapy. 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.

The side effect profile for TSEBT includes itching, dry skin, fissuring, dilated blood vessels, fatigue, temperature dysregulation, sun sensitivity, rash, skin infections, brittle nails, hair loss, and skin cancers. 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.