Improvement in peripheral blood disease burden in patients with Sézary syndrome and leukemic mycosis fungoides after total skin electron beam therapy

Background There is a paucity of effective therapies for patients with Sezary syndrome and advanced mycosis fungoides with peripheral blood involvement. Total skin electron beam (TSEB) radiation therapy is an extremely effective skin-directed therapy for these patients, but, until recently, it was thought not to signifcantly affect the peripheral blood malignant T-cell population. Objective We conducted this study to determine if TSEB has therapeutic effect on the peripheral blood in patients with advanced mycosis fungoides and Sezary syndrome. Methods All patients on stable medication regimens seen in our photopheresis facility who received TSEB therapy between January 2008 and October 2011 at Temple University Hospital, Philadelphia, PA, were analyzed retrospectively for improvement in the peripheral blood, as documented by flow cytometry. Results Six of 11 patients achieved 50% or greater decrease in their peripheral blood malignant T-cell population after TSEB therapy, for an overall response rate of 55%. Within the group of patients who had a response in the skin, 67% also had a response in the peripheral blood. Limitations This analysis is limited in 3 ways. First, the sample described is small. Second, the results may be confounded by the fact that each patient was on other systemic therapies in addition to TSEB, albeit stable pre-existing regimens. The time interval between completion of TSEB therapy and repetition of flow cytometry was not standardized among patients, which may result in an underestimation of the overall response to TSEB therapy. Conclusion In patients with advanced mycosis fungoides and Sezary syndrome, the peripheral blood tumor burden may improve after treatment with TSEB.