Total skin electron beam therapy in the management of cutaneous malignancies

In 1902, Scholtz1 first used ionizing radiation for the treatment of mycosis fungoides (MF); however, not until 1939 did Sommerville2 suggest an “X-Ray bath” for treatment of this T-cell lymphoma. Unfortunately, this technique was limited by such adverse side effects as bone marrow suppression. For the past fifty years, various techniques and dosage regimens have been employed in irradiating the entire skin surface with highenergy electrons.3,4 Total skin electron beam therapy (TSEBT) has been used for various primary or secondary cutaneous malignancies involving large segments of the body, such as MF,7–10,16 lymphoma cutis, cutaneous leukemia,5 Kaposi’s sarcoma,11 and inflammatory breast cancer. Lymphomas and leukemias may initially present as a primary manifestation in some extranodal sites such as the skin. In contrast to MF, primary cutaneous lymphomas are relatively rare, although the secondary cutaneous lymphomas and leukemias involving extensive areas of skin have been treated with TSEBT, mainly for palliation.5 MF is the most common type of cutaneous T-cell lymphoma (CTCL). Methods of treatment currently include systemic or topical steroids, chemotherapy with carmustine (BCNU) or mechlorethamine, PUVA (Psoralen and ultraviolet A), and radiation therapy. The duration of remission achieved by any of these methods is generally related to the stage of the disease and the predominant type of lesion at the time of treatment; i.e., plaque versus nodular lesion. PUVA is currently the most popular method for patch and early plaque lesions. When lesions evolve to tumor stage, however, the greater penetration of ionizing radiation provides a therapeutic advantage over PUVA. MF is radiosensitive and responds equally well to either X-rays or electrons. When extensive areas of the skin are involved, the treatment of choice should be TSEBT because of its physical characteristics. The most important advantage of electron beam treatment over conventional X-rays is its superficial penetrability, permitting very minimal radiation to the underlying normal tissue. The incident energy of the electron beam can be varied depending on the depth of the lesions. Various combinations with photon beam have been used to reduce the thickness of tumoral lesions and to treat locoregional lymph nodes. Classically, the prognosis is poor once MF extends beyond skin to lymph nodes, viscera, peripheral blood, or occasionally to the bone marrow. Patients with extracutaneous disease or with extensive tumoral stage usually prove refractory to therapy and treatment is aimed at palliation. Combined chemotherapy and TSEBT is also effective. Patients who received concurrent chemotherapy and 3,000 cGy of TSEBT incurred increased hematological toxicity but had a significantly higher complete response when compared with the topical mechlorethamine and TSEBT group.6 Unfortunately, the higher rate of complete response did not translate into improved disease-free survival or overall survival. Occasionally, a repeat course of TSEBT has been considered in patients who had recurrence following a long disease-free interval after the initial course of TSEBT and were refractory to other modalities. This second course of TSEBT is mainly for palliation. A median dose of approximately 12–20 Gy has been prescribed.22 A general guideline for treatment of MF is outlined in Table 1. TSEBT is a highly specialized treatment that requires the expertise of a medical physicist, a radiation dosimetrist, and an experienced radiation oncologist who has treated a significant number of patients. The treatment is delivered by a linear accelerator, usually at a treatment distance of approximately 3 meters. The patient stands upright in the path of dual fields, which cover the upper and lower segments of the body. Anterior, posterior, and left and right lateral positions are employed in a 4-field technique, with differential loading From the New York Presbyterian Hospital, Cornell Weill Medical Center, Stich Radiation Center, New York, New York, USA. Address correspondence to Akkamma Ravi, MD, New York Presbyterian Hospital, Cornell Weill Medical Center, Stich Radiation Center, Box. 575, 525 E. 68th Street, New York, NY 10021, USA.