Mycosis fungoides (MF) is the most common type of primary cutaneous T-cell lymphoma (CTCL), affecting middle-aged and elderly population. The clinical manifestations are limited to the skin in early stages (eMF). Skin histopathology, immunohistochemistry and other complementary studies are required, in order to classify MF stages. The prognosis of eMF is favourable, with 98% five-year survival rate for limited patch or plaque disease.1,2

The most recommended treatments for eMF are topical therapies and phototherapy.3 Narrowband UVB phototherapy (NB-UVB) is considered to have a safer profile than PUVA and broadband UVB regarding side effects, tolerability and carcinogenesis.4 Up to the present, most MF and NB-UVB studies were performed on Caucasian and Asian populations with a schedule of three sessions per week.2,5

The aims of this study are to evaluate the response, relapse and side effects of a twice-weekly NB-UVB regimen in eMF. We compared the results with the classic three times a week schedule published in the literature. We also described for the first time the response to NB-UVB therapy in an Argentinean cohort, a mixture of Caucasian and Mestizo people (Amerindian and European ancestry).

We present a retrospective analysis of adult patients (> 18 years old) with confirmed eMF,6 who underwent NB-UVB in the Department of Dermatology at “Hospital Italiano de Buenos Aires” for 8 years. Patient data were obtained from the electronic medical records. No patients presented advanced-stage MF prior to the treatment. NB-UVB treatment scheme is depicted in Table 1. Clinical evaluation was performed every 10 sessions or in the presence of side effects.

Clinical response was classified as complete (CR, >95% of skin lesions clearance), partial (PR, 50% to 95%), stable disease (<50%) and progressive disease. After achieving CR, NB-UVB frequency was reduced once-weekly for 5 weeks and then, discontinued. Remission and relapse were clinically assessed every 3 months and skin biopsies were performed, provided that the clinical picture was unclear. Late relapse was defined as the recurrence of MF more than 12 months after completion of NB-UVB.

We included a cohort of eighteen eMF patients. The study was completed by fifteen patients, while three were excluded as they developed a progressive disease. The eMF population and NB-UVB details are described in Table 2. All twelve CR patients received maintenance and five did not relapse during the follow-up period up to 36 months. Figure 1 shows the response to NB-UVB in eMF patients.

Figure 1.

Female patient with plaque stage MF in both legs. Complete resolution of the skin lesions after 60 sessions of UVB-NB therapy.

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NB-UVB is an effective therapy to improve life quality and to induce a short-term CR in MF. Our cohort of patients was treated with a twice-weekly schedule, reaching a 80% CR in a mean time of 6.1 months. Hofer et al7 reported 6 patients treated with NB-UVB 3-4 times-weekly for 5 to 10 weeks, with a mean cumulative dose (CuD) of 16.3J/cm2. Although 83% of the patients achieved CR, all of them relapsed within 6 months. Gökdemir et al8 published a prospective study with 23 early-stage MF patients, treated with a thrice-weekly schedule. A CR was achieved in 91.3% patients, the mean CuD was 90.3J/cm2 with an average of 36 sessions. In the 3-year follow-up period, only one CR patient relapsed. Relapse rate appears to be related to the CuD, rather than to the number of sessions or the schedule applied. However, we also observed a late relapse in 2 patients, which it would suggest that the response variability is still insufficiently understood.

The establishment of a maintenance therapy should be mandatory as relapse is expected in most of the patients. Boztepe et al described a maintenance therapy based on 80-160 NB-UVB sessions (12-30 months) on a decreasing frequency schedule. During this period, no relapse was observed.9 In regard to avoiding unnecessary energy accumulation and longer therapy, we decided a short-term maintenance, with a close follow-up. Relapsed eMF patients restarted NB-UVB or began PUVA (data not shown).

In order to lower side effects, we apply a common schedule to our cohort and no severe reactions were observed. Despite most publications show a shorter mean time treatment to reach CR (3-4 months), twice-weekly regimen reduces theoretically the risk of acute side effects, as well as the immunosuppressive response in the short term.8–10

A twice-weekly NB-UVB schedule in eMF is as effective as the three-times-weekly regimen. Our CR and relapse rate can be compared to the classic scheme, which confirms that the total amount of energy delivered could be more important than the frequency of exposure or the initial dose. Although longer treatments could be required to reach CuD, we emphasize the low rate of side effects and an adequate treatment compliance. Based on our clinical study, we can recommend a twice-weekly schedule as an alternative to the classical schedule, if patients report intolerance to NB-UVB.