Acta Dermato-Venereologica 99-6CompleteContent | Page 11

544 CLINICAL REPORT Low- vs. Middle-dose Total Skin Electron Beam Therapy for Mycosis Fungoides: An Efficiency-based Retrospective Survey of Skin Response Annelies TAVERNIERS 1 , Aurélie DU THANH 1 , Marie CHARISSOUX 2 , Christine KERR 2 and Olivier DEREURE 1 1 Department of Dermatology, University of Montpellier and INSERM U1058, and 2 Department of Radiotherapy, Montpellier Cancer Institute, Montpellier, France Optimal doses of total skin electron beam therapy for mycosis fungoides remain to be established. Clini- cal efficiency and adverse effects of middle-dose (25 Gy) vs. low-dose (10–12 Gy) total skin electron beam therapy were retrospectively compared in a series of 14 and 12 mycosis fungoides, respectively. Overall skin response rate was 96.2% (92.9% middle-dose and 100% low-dose; not significant (NS)). Overall comple- te and partial skin response rates were 57.7% (42.9% middle-dose and 75% low-dose; NS) and 38.5% (50% middle-dose and 25% low-dose; NS), respectively. All responding patients relapsed after an overall median time of 5 months (7 months middle-dose vs. 4 months low-dose; p  = 0.164, NS). Tolerance was equally fair in both groups, with only grade 1 and 2 adverse events observed in 100% vs. 66.7% of patients in middle-do- se and low-dose groups (NS). Although no significant difference was observed, middle-dose protocol may be recommended owing to a longer relapse-free survival for a similar tolerance. Key words: total skin electron beam therapy; middle dose; low dose; mycosis fungoides. Accepted Jan 16, 2019; E-published Jan 17, 2019 Acta Derm Venereol 2019; 99: 544–550. Corr: Olivier Dereure, Department of Dermatology, Saint-Eloi Hospital, University of Montpellier and INSERM U1058, 80 avenue Augustin Fliche, Montpellier Cedex 5, France. E-mail: [email protected] T reatment options in mycosis fungoides (MF), the most common primary cutaneous T-cell lymphoma, mostly depend on disease stage according to 2017 Euro- pean Organization for Research and Treatment of Cancer (EORTC) staging and the International Society for Cuta- neous Lymphomas (ISCL) classification (1). Therapeutic recommendations have been issued recently by EORTC and clearly separate hierarchized strategies used in early (IA–IIA) vs. advanced (IIB–IVB) stages. Total skin electron beam therapy (TSEBT) has long been used in early stages of the disease and may result in complete or nearly complete and protracted response in some patients and appears as a 2 nd - or 3 rd -line treatment after topical steroids, topical chemotherapy with mechlorethamine and phototherapy in the 2017 EORTC recommendations. Furthermore, it may also be used as a palliative procedure doi: 10.2340/00015555-3124 Acta Derm Venereol 2019; 99: 544–550 SIGNIFICANCE Mycosis fungoides, the most frequent primary cutaneous lymphoma, can be treated with total skin electron beam therapy, usually advocated as a second- or third-line treat­ ment. However, the optimum dose protocol remains to be established. This study indirectly compared 2 dosages (low- and middle-dose) in a retrospective series. A respon- se was obtained in almost all patients regardless of the dosage, but all responding patients relapsed after a relati- vely short delay. Tolerance was fair for both protocols. As relapse-free survival was almost twice as long in the midd- le-dose protocol compared with the low-dose, this might be the best choice for management of mycosis fungoides. However, because middle-dose total skin electron beam therapy, unlike low-dose, can be repeated only once during a patient’s disease course, maintenance treatment should be investigated in this setting. in more advanced stages, although the response rates and duration are less favourable. The most commonly used TSEBT technique is the Stanford 6-dual-field protocol using a conventional 30–36 Gy dose over an 8- to 10- week period. Despite this relatively high dose, relapses are not infrequent, but further irradiation is limited by the potential risk of cumulative radiation toxicity, resulting in TSEBT rarely being administered more than twice, and most commonly once during the disease course (2). To overcome this difficulty, protocols using lower doses (10–12 Gy) have been advocated recently, with similar efficiency compared with the standard dose, but with fewer side-effects. Moreover, this innovative strategy is theoretically consistent with multiple treatment sessions (3, 4). However, middle- and long-term data regarding skin response outcome are often limited precluding an accurate evaluation of the relevance of low doses in a chronic disease for which relapse occurrence and time to relapse are crucial issues. To gain more insight into this issue, a retrospective study was conducted to evaluate the benefit/risk ratio on skin response of middle-dose (25 Gy) vs. low-dose (10–12 Gy) TSEBT in a series of patients with MF treated in the same academic tertiary referral centre over a 20-year period. Relapse areas and possible predictive factors related to response achievement and duration were also investigated. This is an open access article under the CC BY-NC license. www.medicaljournals.se/acta Journal Compilation © 2019 Acta Dermato-Venereologica.