CLINICAL INVESTIGATION Lymphoma A PROSPECTIVE, OPEN-LABEL STUDY OF LOW-DOSE TOTAL SKIN ELECTRON BEAM THERAPY IN MYCOSIS FUNGOIDES MARIA R. KAMSTRUP, M.D.,* LENA SPECHT, M.D., D.M.SC., y GUNHILD L. SKOVGAARD, M.D., D.M.SC.,* AND ROBERT GNIADECKI, M.D., D.M.SC.* * Department of Dermatology, Bispebjerg Hospital, Copenhagen, Denmark; and y Department of Oncology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark Purpose: To determine the effect of low-dose (4 Gy) total skin electron beam therapy as a second-line treatment of Stage IB–II mycosis fungoides in a prospective, open-label study. Methods and Materials: Ten patients (6 men, 4 women, average age 68.7 years [range, 55–82 years]) with histo- pathologically confirmed mycosis fungoides T2–T4 N0–N1 M0 who did not achieve complete remission or relapsed within 4 months after treatment with psoralen plus ultraviolet-A were included. Treatment consisted of low-dose total skin electron beam therapy administered at a total skin dose of 4 Gy given in 4 fractions over 4 successive days. Results: Two patients had a complete clinical response but relapsed after 3.5 months. Six patients had partial clin- ical responses, with a mean duration of 2.0 months. One patient had no clinical response. Median time to relapse was 2.7 months. One patient died of unrelated causes and did not complete treatment. Acute side effects included desquamation, xerosis, and erythema of the skin. No severe side effects were observed. Conclusion: Low-dose total skin electron beam therapy can induce complete and partial responses in Stage IB–II mycosis fungoides; however, the duration of remission is short. Low-dose total skin electron beam therapy may find application in palliative treatment of mycosis fungoides because of limited toxicity and the possibility of repeating treatments for long-term disease control. Ó 2008 Elsevier Inc. Cutaneous lymphomas, Mycosis fungoides, Radiotherapy, Low-dose total skin electron beam therapy. INTRODUCTION Mycosis fungoides (MF) is a cutaneous T cell lymphoma typically exhibiting an indolent clinical course. As long as the patient remains in the early stages the prognosis is very good, with a 10-year risk of disease progression of 5–10% in Stage IA and 17–39% in Stage IB (1–3). Relative risk of death increases with disease progression (0.7 in Stage IA, 2.2 in IB/IIA, 3.9 in IIB/III, and 12.8 in IV) (4). Because current treatment modalities are not curative and re- treatments are necessary, having treatment options suitable for long-term control is essential. Ionizing radiation presents a very effective treatment modality for MF (5, 6). In contrast to X-ray therapy, electron beam therapy (EBT) has minimal penetration to lower dermis and deeper tissues and therefore fewer side effects (7, 8). Electron beam therapy is generally applied to the skin in total doses of 30–36 Gy over an 8– 10-week period, resulting in complete response rates ranging from 98% for limited plaque stage to 36% for tumor stage (9– 11) and remissions of 1–3 years (9, 10, 12). Because of the potential risk of toxicity including bone marrow suppression, no more than two to three courses of total skin EBT (TSEBT) in a lifetime are generally recommended (12, 13). In the present study we explored the possibility of using lower radiation doses for TSEBT, which could limit toxicities and allow this treatment to be repeated for long-term disease control. We were especially encouraged by results obtained with low-dose radiation treatment of indolent noncutaneous non-Hodgkin’s B cell lymphomas. In early stages, photon beam therapy of 20–25 Gy has traditionally been used to obtain prolonged disease-free survival (14–16). In advanced stages, low-dose fractionated total body photon beam irradi- ation (1.5–2.0 Gy) has been shown to result in high response rates and recurrence-free survival (17–19) and to be as effective as chemotherapy regimens (17, 18, 20). Subsequent studies have furthermore demonstrated that low-dose, limited-field radiotherapy of nodal masses is beneficial in advanced low-grade non-Hodgkin’s lymphomas (21–23). In this report we show that a clinical response of MF Stage I–II is obtainable with low-dose TSEBT (total 4 Gy). However, the duration of the clinical response proved to be Reprint requests to: Robert Gniadecki, M.D., D.M.Sc., Depart- ment of Dermatology D, Bispebjerg Hospital, Bispebjerg Bakke 23, 2400 Copenhagen NV, Denmark. Tel: (+45) 3531-3165; Fax: (+45) 3531-3113; E-mail: rg01@bbh.regionh.dk Conflict of interest: none. Received Sept 21, 2007, and in revised form Oct 25, 2007. Accepted for publication Nov 12, 2007. 1204 Int. J. Radiation Oncology Biol. Phys., Vol. 71, No. 4, pp. 1204–1207, 2008 Copyright Ó 2008 Elsevier Inc. Printed in the USA. All rights reserved 0360-3016/08/$–see front matter doi:10.1016/j.ijrobp.2007.11.039