Total Skin Electron Beam Therapy in the Treatment of Mycosis Fungoides: A Review of Conventional and Low-Dose Regimens

On the Way to Curing Advanced-Stage Mycosis Fungoides/Sézary Syndrome

INTRODUCTION/BACKGROUND

Advanced-stage mycosis fungoides (MF) and Sézary syndrome (SS) have poor prognosis with median survivals of less than 5 years. Although a variety of treatments are approved for MF/SS patients, durable complete remissions (CR) are rare.

PATIENTS AND METHODS

Advanced-stage MF or SS patients who achieved CR and maintained in CR or stage IA for more than 10 years were identified by a retrospective search of the principal investigator's database.

RESULTS

Of 2266 patients diagnosed with MF or SS, 23 patients with advanced-stage MF/SS (6 IIB, 1 IIIB, 5 IVA1, 3 IVA2, 8 IVB) who achieved CR and maintained in CR or stage IA for ≥ 10 years were identified. As final/curative treatment, 11 patients underwent allogeneic stem cell transplantation (SCT). Most patients presented at young age, underwent SCT with reduced intensity conditioning regimen, had matched related donors, and controllable post-transplant graft versus host disease. Eleven patients were treated with TSEB as part of combined modality protocol in 2 patients and debulking therapy before allogeneic SCT in 9 patients. Five stage IIB patients achieved CR with radiotherapy. Four patients with blood involvement were treated with extracorporeal photopheresis (ECP) in combination with long-term antibiotics and immunomodulatory agents. Long-term antibiotics were given to 14 patients.

CONCLUSION

TSEB followed by allogeneic SCT, radiotherapy, ECP plus long-term antibiotics and immunomodulatory agents were the most common curative/final treatments found in our patients. We are reporting the details of our long-term complete responders' treatment course in the hopes of obtaining more cure responses in the future.

Accelerated Low-Dose Total Skin Electron Beam Therapy Using the Modified Stanford Technique: An In Vivo Dosimetry Confirmation Study

Purpose Low-dose total skin electron beam therapy (LD-TSEBT) has recently gained popularity in treating mycosis fungoides (MF) due to its reduced toxicity and favorable response rates. Combining accelerated LD-TSEBT with the modified Stanford technique (mST), a condensed cycling approach, offers a promising and convenient option. However, in vivo dosimetry data confirming the effectiveness of this approach is limited. We retrospectively analyzed in vivo data from patients who received accelerated LD-TSEBT using the mST for MF. Methods Patients treated with accelerated LD-TSEBT using the mST for MF were identified. Optically stimulated radiation dosimeters (OSLDs) were used to measure doses at 10 anatomical sites: vertex, larynx, right shoulder, right forearm, right hip, umbilicus, left medial thigh, right knee, left dorsal foot, and left dorsal hand. Measurements were aggregated and compared to the prescribed dose, using the European Organisation For Research And Treatment Of Cancer (EORTC) homogeneity tolerance criteria, which account for the American Association of Physicians in Medicine (AAPM) TG023 setup variability: ±20% of the prescribed dose. Patient characteristics, demographics, and disease details were also collected. Descriptive statistics were performed to evaluate clinical and dosimetric characteristics. Results Thirty-six patients were identified, and 360 OSLD measurements were recorded. The median of all OSLD measurements relative to the prescribed dose at all sites was 97.4%. The highest median delivered dose was recorded at the umbilicus (106%) and the lowest at the left dorsal hand (79%). After accounting for deviation at the left dorsal hand, 85.8% of all OSLD measurements met the homogeneity criteria at the other anatomic sites. Other patient metrics, such as height and BMI, did not impact the median delivered OSLD dose or number of anatomical sites per patient meeting the EORTC tolerance criteria. Conclusion Accelerated LD-TSEBT using the mST delivers accurate doses, with most subjects meeting the EORTC tolerance criteria. This study supports the use of OSLDs for in vivo dosimetry in patients undergoing this regimen, ensuring adequate dosing despite the truncated cycling approach.

A scattering-foil free electron beam to increase dose rate for total skin electron therapy (TSET)

BACKGROUND

Electron beams are used at extended distances ranging between 300 to 700 cm to uniformly cover the entirety of the patient's skin for total skin electron therapy (TSET). Even with electron beams utilizing the high dose rate total skin electron (HDTSe) mode from the Varian 23iX or TrueBeam accelerators, the dose rate is only 2500 cGy/min at source-to-surface distance (SSD) = 100 cm. At extended distances, the decrease in dose rate leads to long beam delivery times that can limit or even prevent the use of the treatment for patients who, in their weakened condition, may be unable to stand on their own for extended periods of time. Previously, to increase dose rate, a customized 6 MeV electron beam was created by removing the x-ray target, flattening filter, beam monitor chamber, and so forth. from the beam path (Chen, et at IJROBP 59, 2004) for TSET. Using this scattering-foil free (SFF) electron beam requires the treatment distance be extended to 700 cm to achieve dose uniformity from the single beam. This room size requirement has limited the widespread use of the 6 MeV-SFF beam.

PURPOSE

This study explores an application of a dual-field technique with a 6 MeV-SFF beam to provide broad and uniform electron fields to reduce the treatment distances in order to overcome treatment room size limitations.

METHODS

The EGSnrc system was used to generate incident beams. Gantry angles between 6 MeV-SFF dual-fields were optimized to achieve the similar patient skin dose distribution resulting from a standard 6 MeV-HDTSe dual-field configuration. The patient skin dose comparisons were performed based on the patient treatment setup geometries using dose-volume-histograms.

RESULTS

Similar dose coverage can be achieved between 6 MeV-SFF and 6 MeV-HDTSe beams by reducing gantry angles between dual-field geometries by 8° and 7° at treatment distances of 400 and 500 cm, respectively. To achieve 95% mean dose to the first 5 mm of skin depth in the torso area, the mean dose to depths of 5-10 mm and 10-15 mm below the skin surface was 74% (74%) and 49% (50%) of the prescribed dose when using 6 MeV-SFF (6 MeV-HDTSe) beam, respectively.

CONCLUSIONS

The 6 MeV-SFF electron beam is feasible to provide similar TSET skin dose coverage at SSD ≥ 400 cm using a dual-field technique. The dose rate of the 6 MeV-SFF beam is about 4 times that of current available 6 MeV-HDTSe beams at treatment distances of 400-500 cm, which significantly shortens the treatment beam-on time and makes TSET available to patients in weakened conditions.

Fine-Tuning Low-Dose Total Skin Electron Therapy for Optimal Management of Cutaneous T-Cell Lymphoma: A Comparative Analysis of Regimens

Purpose

Low-dose total skin electron beam therapy (TSEBT) is a proven treatment for managing cutaneous T-cell lymphoma (CTCL) and Sezary syndrome with skin burden. We performed a retrospective comparison of response rates and time to progression for patients receiving low-dose TSEBT based on dose per fractionation, total dose, and stage.

Methods and Materials

One hundred and ten patients with CTCL and Sezary syndrome were treated with 135 courses of low-dose (400-1500 cGy) TSEBT or subtotal skin electron therapy at multiple centers of a single institution between August 2003 and June 2023. Patients were stratified according to total dose, dose per fraction, and stage.

Results

The median follow-up was 301 days (IQR, 141, 767). The median age at treatment was 69.9 years (range, 29.7-96.5). T-stage distribution was as follows: 3 (2.7%) T1, 74 (67.3%) T2, 16 (14.5%) T3, and 17 (15.5%) T4. American Joint Committee on Cancer eighth edition stage distribution was as follows: 3 (2.7%) IA, 53 (48.2%) IB, 3 (2.7%) IIA, 16 (14.5%) IIB, 8 (7.3%) IIIA, 19 (17.3%) IVA, and 8 (7.3%) IVB. There was no significant difference in disease distribution between patients treated with different fractionation schemes. The overall response rate was 89.6%. Forty-four courses (32.6%), 34 courses (25.2%), and 43 (31.9%) resulted in a complete, near-complete, and partial response, respectively. Fourteen courses (10.4%) resulted in no clinical response. For all patients, the median time to response was 43.0 days (IQR, 23.0-70). The median time to skin progression for all patients was 107.5 days (IQR, 67.8-233.5).

Conclusions

This analysis demonstrated that CTCL patients treated with low-dose radiation therapy delivered over various fractionation schemes had similar overall response rates and median time to progression.

Unleashed monocytic engagement in Sézary syndrome during the combination of anti-CCR4 antibody with type I interferon

ABSTRACT

Sézary syndrome (SS) is an aggressive leukemic expansion of skin-derived malignant CD4+ T cells. Drug monotherapy often results in disease relapse because of the heterogenous nature of malignant CD4+ T cells, but how therapies can be optimally combined remains unclear because of limitations in understanding the disease pathogenesis. We identified immunologic transitions that interlink mycosis fungoides with SS using single-cell transcriptome analysis in parallel with high-throughput T-cell receptor sequencing. Nascent peripheral CD4+ T cells acquired a distinct profile of transcription factors and trafficking receptors that gave rise to antigenically mature Sézary cells. The emergence of malignant CD4+ T cells coincided with the accumulation of dysfunctional monocytes with impaired fragment crystallizable γ-dependent phagocytosis, decreased responsiveness to cytokine stimulation, and limited repertoire of intercellular interactions with Sézary cells. Type I interferon supplementation when combined with a monoclonal antibody targeting the chemokine receptor type 4 (CCR4), unleashed monocyte induced phagocytosis and eradication of Sézary cells in vitro. In turn, coadministration of interferon-α with the US Food and Drug Administration-approved anti-CCR4 antibody, mogamulizumab, in patients with SS induced marked depletion of peripheral malignant CD4+ T cells. Importantly, residual CD4+ T cells after Sézary cell ablation lacked any immunologic shifts. These findings collectively unveil an auxiliary role for augmenting monocytic activity during mogamulizumab therapy in the treatment of SS and underscore the importance of targeted combination therapy in this disease.

Challenges in commissioning the "TSET" technique: A new approach towards monitor unit calculation and beam profile measurements

INTRODUCTION

Total skin electron beam therapy, commonly known as TSET, is a good choice of treatment for patients suffering from mycosis fungoides. The aim of this study was to introduce a new approach to the beam profile measurement using diodes and to calculate the monitor units required for the TSET treatment by the use of a simple setup of output measurement. Dosimetric measurements required for the treatment were taken to establish the Stanford technique in the department, and the measured data was compared with the published data.

MATERIALS AND METHODS

High-energy Linear Accelerator Clinac-DHX, Varian medical system, Palo Alto, CA, was commissioned for TSET. The output of the machine was measured by the use of a Parallel-Plate Chamber (PPC40) as per the TRS 398 recommendation. Diode dosimeters (EDD2 and EDD5) were used for beam profile measurements due to easy setup and to reduce the measurement time.

RESULTS

Homogeneous dose distribution within a field size of 80 cm x160 cm was observed with the variation of -5.0% on the horizontal axis and -5.4% on the vertical axis. The calculated monitor unit to deliver 200 cGy per fraction per field at the source to surface (SSD) of 416 cm was 489 MU.

CONCLUSION

The technique described for the output measurements is simple and accurate. Results of the absorbed dose and MU measured were within good agreement compared to the published literature.

Overcoming Chemotherapy Resistance in Cutaneous T-Cell Lymphoma: A Successful Case of High-Dose Radiotherapy Management

The management of refractory cutaneous T-cell lymphoma (CTCL) is challenging and requires a multimodal approach. Radiotherapy is one of the treatment options used in managing CTCL, particularly for localized disease or as a palliative measure to control symptoms in advanced cases. The rarity of the disease makes it difficult to conduct extensive clinical trials and gather sufficient data on the most effective treatment approaches. Lymphocytes are among the most sensitive cells to radiation's damaging effects. Because of this sensitivity, radiation therapy can be an effective treatment. This case illustrates the efficacy of radiotherapy and its potential as an effective treatment alternative for a severe and resistant CTCL to systemic therapy in a 61-year-old Moroccan patient. The patient underwent curative high-dose radiation therapy, utilizing three-dimensional conformal radiation therapy. At the 19-month follow-up post-radiotherapy, no evidence of local recurrence, either clinically or radiologically, was observed, and the patient maintained a good quality of life with unrestricted mobility of his arm.

Life after total skin electron irradiation; A perspective through the eyes of a radiation oncologist

Mycosis fungoides (MF) remains a challenge as a disease from its diagnosis through treatment and follow-up. The rarity of the disease and uncharacteristic clinical manifestations pose difficulty in diagnosis, and the lack of treatment facilities adds to the management woes. Though the Stanford technique is the most accepted modality of total skin electron beam therapy (TSEBT), the implementation details are still unstandardized. Different centers adopt different methodologies as per their convenience and suitability. We present a patient of MF with many dimensions of prediagnosis clinical features to the diagnosis, treatment, and follow-up with subsequent developments over a period of 24 years that may help to understand the disease and management in a better manner.

Investigation of total skin helical tomotherapy using a 3D-printed total skin bolus

OBJECTIVE

To investigate the effectiveness of using a 3D-printed total skin bolus in total skin helical tomotherapy for the treatment of mycosis fungoides.

MATERIALS AND METHODS

A 65-year-old female patient with a 3-year history of mycosis fungoides underwent treatment using an in-house desktop fused deposition modelling printer to create a total skin bolus made of a 5-mm-thick flexible material, which increased the skin dose through dose building. The patient's scan was segmented into upper and lower sections, with the division line placed 10 cm above the patella. The prescription was to deliver 24 Gy over 24 fractions, given 5 times per week. The plan parameters consisted of a field width of 5 cm, pitch of 0.287 and modulation factor of 3. The complete block was placed 4 cm away from the planned target region to reduce the area of the internal organs at risk, especially the bone marrow. Dose delivery accuracy was verified using point dose verification with a "Cheese" phantom (Gammex RMI, Middleton, WI), 3D plane dose verification with ArcCHECK (Model 1220, Sun Nuclear, Melbourne, FL), and multipoint film dose verification. Megavoltage computed tomography guidance was also utilized to ensure the accuracy of the setup and treatment.

RESULTS

A 5-mm-thick 3D-printed suit was used as a bolus to achieve a target volume coverage of 95% of the prescribed dose. The conformity index and homogeneity index of the lower segment were slightly better than those of the upper segment. As the distance from the skin increased, the dose to the bone marrow gradually decreased, and the dose to other organs at risk remained within clinical requirements. The point dose verification deviation was less than 1%, the 3D plane dose verification was greater than 90%, and the multipoint film dose verification was less than 3%, all of which confirmed the accuracy of the delivered dose. The total treatment time was approximately 1.5 h, which included 0.5 h of wearing the 3D-printed suit and 1 h with the beam on. Patients only experienced mild fatigue, nausea or vomiting, low-grade fever, and grade III bone marrow suppression.

CONCLUSION

The use of a 3D-printed suit for total skin helical tomotherapy can result in a uniform dose distribution, short treatment time, simple implementation process, good clinical outcomes, and low toxicity. This study presents an alternative treatment approach that can potentially yield improved clinical outcomes for mycosis fungoides.

Total Skin Treatment with Helical Arc Radiotherapy

For widespread cutaneous lymphoma, such as mycosis fungoides or leukemia cutis, in patients with acute myeloid leukemia (AML) and for chronic myeloproliferative diseases, total skin irradiation is an efficient treatment modality for disease control. Total skin irradiation aims to homogeneously irradiate the skin of the entire body. However, the natural geometric shape and skin folding of the human body pose challenges to treatment. This article introduces treatment techniques and the evolution of total skin irradiation. Articles on total skin irradiation by helical tomotherapy and the advantages of total skin irradiation by helical tomotherapy are reviewed. Differences among each treatment technique and treatment advantages are compared. Adverse treatment effects and clinical care during irradiation and possible dose regimens are mentioned for future prospects of total skin irradiation.

Paraffin gauze bolus as tissue compensator in photon irradiation for mycosis fungoides – regarding a case study

Introduction:

Total skin electron beam therapy is a treatment option in patients with mycosis fungoides (MF) affecting a significant amount of the body surface. For patients with involvement of soles and interdigital folds, however, this approach is ineffective, requiring alternatives such as localised radiotherapy (RT). Although electron beams are well suited for superficial lesions, on irregular surfaces it provides inadequate tumour coverage and excess dose variance, requiring photon irradiation with tissue compensation.

Methods:

We present the case of a patient with extensive cutaneous MF with skin lesions spread over both lower limbs and treated on these affected areas with photon beam RT. Long sheets of paraffin gauze dressings were used to create a 0·5-cm-thick bolus. The patient received a single fraction of 8 Gy. In vivo dosimetry using Gafchromic films was performed.

Results:

After 3 months, a complete response was achieved. In this case, paraffin gauze bolus proved to be an inexpensive, convenient, effective and flexible method for irregular superficial cancer irradiations.

Conclusion:

Paraffin gauze bolus is a suitable option for irregular contours.

Skin dose distributions between Stanford and rotational techniques in total skin electron therapy (TSET)

PURPOSE

Total skin electron therapy (TSET) has proven to be one of the most effective treatments for advanced-stage cutaneous T-cell lymphoma. Two most used techniques are the Stanford six-field and rotational techniques. This study compares patient skin dose distributions as a function of depth between these two techniques.

METHODS

The EGSnrc system was used to simulate electron beams and calculate patient dose distributions. The calculations assumed the same patient standing on a platform and the patient's different postures were ignored for the Stanford technique in the comparison of dose distributions. The skin doses were analyzed as a function of skin depth-dose coverage and evaluated using dose-volume-histograms (DVH). The comparisons were performed in three realistic clinical settings in which dual-field were used for patients treated at extended distances of 316 cm and 500 cm, and a single field was used at 700 cm. In all cases the realistic patient treatment beam delivery geometry was simulated.

RESULTS

Although small dose differences were observed in some local areas, no clinically significant differences were found in the patient 3D dose distributions between the Stanford and rotational techniques. Virtually the same DVH curves between two the techniques were observed for mean dose to skin depth of 0-5 mm, 5-10 mm and 10-15 mm from the skin surface, respectively. It is found that the skin depth dose coverage is 2 mm shallower for patient treatment at 500 cm compared to at 316 cm due to the additional air attenuation. However, very similar dose coverage and uniformity can be achieved at these two different extended treatment distances by adjusting the thickness of acrylic scatter plate. Adequate thickness of a scattering plate improves the skin dose uniformity.

CONCLUSION

Both the Stanford and rotational techniques deliver very similar skin dose coverage in DVH plots and only small differences are seen in local areas. It is worth to emphasize that the dose-volume histogram (DVH) is a graphical representation of the distribution of dose within a structure and it does not contain spatial information. Therefore, comparison of entire skin dose using DVH may mask some variations at different locations of the surface area. In addition, the comparison did not consider different patient postures of the Stanford technique. Including the different patient postures in the calculation may affect the result of doses to the limbs. This article is protected by copyright. All rights reserved.

Development of transparent eye shields for total skin electron beam radiotherapy

Purpose

For total skin electron (TSE) beam radiation therapy, the anterior eye and conjunctiva can be protected with eye shields to prevent keratitis, xerophthalmia, and cataractogenesis. Conventional metal eye shields can reduce patient balance by obscuring vision and thus increasing the risk for falls. We report on the design, fabrication, and clinical use of transparent acrylic eye shields for TSE.

Methods

The primary design goals were a seven‐fold reduction in the dose to the anterior eye and conjunctiva to meet published dose‐recommendations, preservation of vision for the wearer, and biocompatibility for external use. Resembling thick swim goggles, the design features 23 mm thick acrylic lenses that are mounted in a 3‐D printed support structure that conforms to the eye socket and can be worn with a strap. Dose measurements were performed in a simulated Stanford‐technique treatment with an anthropomorphic phantom using Gafchromic EBT film

Results

The transparent eye shields were manufactured using a 3D‐printer and CNC‐machine. Based on measurements from the simulated treatments for each of the eye shields, the eye shields provided a 12‐fold reduction in dose to the lens. After use in more than 200 fractions, the shields were well tolerated by patients, and there were no reports of any incidents or adverse events.

Conclusion

Transparent TSE eye shields are able to reduce the dose to the eyes while maintaining vision during treatment at a reasonable cost.

Quantitative evaluation of dosimetric uncertainties associated with small electron fields

INTRODUCTION

Although many studies have investigated small electron fields, there are several dosimetric issues that are not well understood. This includes lack of charged particle equilibrium, lateral scatter, source occlusion and volume averaging of the detectors used in the measurement of the commissioning data. High energy electron beams are also associated with bremsstrahlung production that contributes to dose deposition, which is not well investigated, particularly for small electron fields. The goal of this work has been to investigate dosimetric uncertainties associated with small electron fields using dose measurements with different detectors as well as calculations with eMC dose calculation algorithm.

METHODS

Different dosimetric parameters including output factors, depth dose curves and dose profiles from small electron field cutouts were investigated quantitatively. These dosimetric parameters were measured using different detectors that included small ion chambers and diodes for small electron cutouts with diameters ranging from 15-50mm mounted on a 6 × 6cm² cone with beam energies from 6-20MeV.

RESULTS

Large deviations existed between the output factors calculated with the eMC algorithm and measured with small detectors for small electron fields up to 55% for 6MeV. The discrepancy between the calculated and measured doses increased 10%-55% with decreasing electron beam energy from 20 MeV to 6 MeV for 15mm circular field. For electron fields with cutouts 20mm and larger, the measured and calculated doses agreed within 5% for all electron energies from 6-20MeV. For small electron fields, the maximal depth dose shifted upstream and becomes more superficial as the electron beam energy increases from 6-20MeV as measured with small detectors.

DISCUSSION

Large dose discrepancies were found between the measured and calculated doses for small electron fields where the eMC underestimated output factors by 55% for small circular electron fields with a diameter of 15 mm, particularly for low energy electron beams. The measured entrance doses and d_max of the depth dose curves did not agree with the corresponding values calculated by eMC. Furthermore, the measured dose profiles showed enhanced dose deposition in the umbra region and outside the small fields, which mostly resulted from dose deposition from the bremsstrahlung produced by high energy electrons that was not accounted for by the eMC algorithm due to inaccurate modeling of the lateral dose deposition from bremsstrahlung.

CONCLUSION

Electron small field dosimetry require more consideration of variations in beam quality, lack of charged particle equilibrium, lateral scatter loss and dose deposition from bremsstrahlung produced by energetic electron beams in a comprehensive approach similar to photon small field dosimetry. Furthermore, most of the commercially available electron dose calculation algorithms are commissioned with large electron fields; therefore, vendors should provide tools for the modeling of electron dose calculation algorithms for small electron fields.

Quantitative evaluation of dosimetric uncertainties in electron therapy by measurement and calculation using the electron Monte Carlo dose algorithm in the Eclipse treatment planning system

In the electron beam radiation therapy, customized blocks are mostly used to shape treatment fields to generate conformal doses. The goal of this study is to investigate quantitatively dosimetric uncertainties associated with heterogeneities, detectors used in the measurement of the beam data commissioning, and modeling of the interactions of high energy electrons with tissue. These uncertainties were investigated both by measurements with different detectors and calculations using electron Monte Carlo algorithm (eMC) in the Eclipse treatment planning system. Dose distributions for different field sizes were calculated using eMC and measured with a multiple-diode-array detector (MapCheck2) for cone sizes ranging from 6 to 25 cm. The dose distributions were calculated using the CT images of the MapCheck2 and water-equivalent phantoms. In the umbra region (<20% isodose line), the eMC underestimated dose by a factor of 3 for high energy electron beams due to lack of consideration of bremsstrahlung emitted laterally that was not accounted by eMC in the low dose region outside the field. In the penumbra (20%-80% isodose line), the eMC overestimated dose (40%) for high energy 20 MeV electrons compared to the measured dose with small diodes in the high gradient dose region. This was mainly due to lack of consideration of volume averaging of the ion chamber used in beam data commissioning which was input to the eMC dose calculation algorithm. Large uncertainties in the CT numbers (25%) resulted from the image artifacts in the CT images of the MapCheck2 phantom due to metal artifacts. The eMC algorithm used the electron and material densities extracted from the CT numbers which resulted large dosimetric uncertainties (10%) in the material densities and corresponding stopping power ratios. The dose calculations with eMC are associated with large uncertainties particularly in penumbra and umbra regions and around heterogeneities which affect the low dose level that cover nearby normal tissue or critical structures.

Technical Note: Bremsstrahlung dose in the electron beam at extended distances in total skin electron therapy

PURPOSE

Electron beam from a linear accelerator is commonly used in total skin electron Therapy (TSET) at extended distances. Since Das et al (Med Phys 21, p.1733, 1994) reported 5% bremsstrahlung dose for a 6 MeV electron beam at extended distance of 500 cm it has been accepted as common knowledge. However, measurements by Chen et al (Int J. Rad Onc Biol Phys 59 p.872, 2004) and Monte Carlo simulations by Ding et al (Phys. Med. Biol. 66, 075010, 2021) were unable to reproduce such high bremsstrahlung dose. As bremsstrahlung dose contributes to whole-body dose which could produce bone marrow toxicity with serious complications for the outcome of the TSET, it is important to re-evaluate the magnitude of bremsstrahlung dose accurately.

METHODS

The EGSnrc Monte Carlo system is used to investigate bremsstrahlung doses from 6 MeV high dose rate total skin electron (HDTSe) beams from Varian TrueBeam and Clinac Accelerators. The measurements were carried out at depth of d_max and 5 cm in solid water and Acrylic phantoms at extended distances using a parallel-plate chamber and a cylindrical ion chamber.

RESULTS

We were able to reproduce previously reported high bremsstrahlung dose at extended distances by using a parallel plate ionization chamber. However, both the measurements by using a cylindrical chamber and Monte Carlo simulations showed an insignificant bremsstrahlung dose (∼1%) even at SSD = 500 cm.

CONCLUSION

The bremsstrahlung doses of a 6 MeV electron beam are 0.5% to 1% for SSD from 100 to 700 cm, although it increases with the increasing extended distance. The common belief of up to 5% bremsstrahlung dose at large extended distances is incorrect. Previously reported high bremsstrahlung doses might be due to poor signal-to-noise ratio of using parallel plate chamber for measuring very low dose or particular set-up. This article is protected by copyright. All rights reserved.

Stopping-power ratios for electron beams used in total skin electron therapy

PURPOSE

The electron beams for total skin electron therapy (TSET) are often degraded by a scatter plate in addition to extended distances. For electron dosimetry, both the AAPM TG-51 and IAEA TRS-398 recommend the use of two formulas developed by Burns et al [Med. Phys. 23, 489-501 (1996)] to estimate the water-to-air stopping-power ratios (SPRs). Both formulas are based on a fit to SPRs calculated for standard electron beams. This study aims to find: (1) if the formulas are applicable to beams used in TSET and (2) the impact of the ICRU report 90 recommendations on the SPRs for these beams.

METHODS

The EGSnrc Monte Carlo code system is used to generate 6 MeV high dose rate total skin electron (HDTSe) beams used in TSET. The simulated beams are used to calculate dose distributions and SPRs as a function of depth in a water phantom. The fitted SPRs using the empirical formulas are compared with MC-calculated SPRs.

RESULTS

The electron beam quality specifier, the depth in water at which the absorbed dose falls to 50% of its maximum value, R₅₀ , decreases approximately 1 mm for each additional 100-cm extended distance ranging from 2.24 cm at SSD = 100 to 1.72 cm at SSD = 700 cm. For beams passing through a scatter plate, R₅₀ is 1.76 cm (1.14) at SSD = 300 and 1.48 cm (0.85 cm) at SSD = 600 cm with an Acrylic plate thickness of 3 mm (9 mm), respectively. The discrepancy between fitted and MC-calculated SPRs at d_ref as a function of R₅₀ is <0.8%, and in many cases <0.4%. The difference between fitted and MC-calculated SPRs as a function of depth and R₅₀ is within 1% at depths <0.8R₅₀ for beams with R₅₀  ≥ 1.14 cm. The ICRU-90 recommendations decrease SPRs by 0.3%-0.4% compared to the use of data recommended in ICRU-37.

CONCLUSION

The formulas used by the major protocols are accurate enough for clinical beams used in TSET and the error caused using the formulas is <1% to estimate SPRs as a function of depth and R₅₀ for depths <0.8R₅₀ for beams used in TSET with R₅₀  ≥ 1.14 cm. The impact of the ICRU-90 recommendations shows a decrease of SPRs by a fraction of a percent for beams used in TSET.

Monte Carlo study on dose distributions from total skin electron irradiation therapy (TSET)

Total skin electron therapy (TSET) has been used to treat mycosis fungoides since the 1950s. Practitioners of TSET rely on relatively crude, phantom-based point measurements for commissioning and treatment plan dosimetry. Using Monte Carlo simulation techniques, this study presents whole-body dosimetry for a patient receiving rotational, dual-field TSET. The Monte Carlo codes, BEAMnrc/DOSXYZnrc, were used to simulate 6 MeV electron beams to calculate skin dose from TSET. Simulations were validated with experimental measurements. The rotational dual-field technique uses extended source-to-surface distance with an acrylic beam degrader between the patient and incident beams. Simulations incorporated patient positioning: standing on a platform that rotates during radiation delivery. Resultant patient doses were analyzed as a function of skin depth-dose coverage and evaluated using dose-volume-histograms (DVH). Good agreement was obtained between simulations and measurements. For a cylinder with a 30 cm diameter, the depths that dose fell to 50% of the surface dose was 0.66 cm, 1.15 cm and 1.42 cm for thicknesses of 9 mm, 3 mm and without an acrylic scatter plate, respectively. The results are insensitive to cylinder diameter. Relatively uniform skin surface dose was obtained for skin in the torso area although large dose variations (>25%) were found in other areas resulting from partial beam shielding of the extremities. To achieve 95% mean dose to the first 5 mm of skin depth, the mean dose to skin depth of 5-10 mm and depth of 10-15 mm from the skin surface was 74% (57%) and 50% (25%) of the prescribed dose when using a 3mm (9 mm) thickness scatter plate, respectively. As a result of this investigation on patient skin dose distributions we changed our patient treatments to use a 3 mm instead of a 9 mm thickness Acrylic scatter plate for clinically preferred skin depth dose coverage.

Mycosis Fungoides and Sézary Syndrome: Updates and Review of Current Therapy

OPINION STATEMENT

While most patients with early-stage mycosis fungoides (MF) follow an indolent course, patients with advanced-stage MF/Sézary syndrome (SS) have a poor prognosis with a median survival of less than 5 years. Although there are a number of treatments currently available, achieving and maintaining a durable response remain challenging, especially in advanced-stage MF/SS. The choice of frontline therapy is dependent on the stage of disease. For early-stage MF, the treatment concept is to control skin lesions mainly by skin-directed therapies, such as topical therapies, phototherapies, and radiotherapies. For advanced-stage MF/SS, systemic treatments by biological or targeted therapies including bexarotene and interferon either alone or in combination are tried first, with more immunosuppressive chemotherapies being reserved for refractory or rapidly progressive disease. Recent improvements in biological or targeted therapies include brentuximab vedotin and mogamulizumab. When biopsy samples have 10% or more CD30-positive malignant cells, brentuximab vedotin, an anti-CD30 antibody conjugated to monomethyl auristin E, can be a desirable treatment option. For cases with blood involvement, mogamulizumab, an antibody binding to C-C chemokine receptor 4, is effective with high response rates. In the refractory setting, alemtuzumab, histone deacetylase inhibitors, pralatrexate, gemcitabine, and doxorubicin are considered as the treatment option. Because only allogeneic hematopoietic stem cell transplantation can offer a chance of cure with durable complete remission, advanced-stage patients with a markedly short life expectancy should be evaluated for eligibility. Given that there are few randomized controlled studies in the literature, it is necessary to investigate which therapy is preferable for each patient with MF/SS by comparative prospective trials.

Low-Dose Total Skin Electron Beam Therapy as Part of a Multimodality Regimen for Treatment of Sézary Syndrome: Clinical, Immunologic, and Molecular Analysis

Importance

Sézary syndrome (SS) is an advanced form of cutaneous T-cell lymphoma with few long-term remissions observed.

Objective

To profile 3 patients with SS who have experienced long-term remission following the addition of low-dose total skin electron beam therapy (TSEBT) to systemic regimens of extracorporeal photopheresis, bexarotene, and interferon-γ.

Design, Setting, and Participants

This is a retrospective case series with additional investigations of patient-donated samples to assess therapeutic response. The study was conducted at the University of Pennsylvania Cutaneous Lymphoma Clinic and follows 3 patients with stage IVA1 CD4+ SS who presented to the clinic between November 1, 2009, and November 1, 2017, and who had a history of SS that was refractory to multimodality systemic therapy prior to receiving low-dose TSEBT.

Interventions

Patients were treated in a multimodality fashion with combined extracorporeal photopheresis, bexarotene, interferon-γ, and low-dose TSEBT.

Main Outcomes and Measures

To characterize treatment responses in these patients, the extent of skin disease was measured with the modified severity weighted assessment tool. Blood disease was measured with flow cytometric assessments of Sézary cell count, CD4:CD8 ratio, and high throughput sequencing of the T-cell receptors. To assess for restoration of immune function, we measured markers of immune exhaustion, including PD-1 (programmed cell death 1), TIGIT (T-cell immunoreceptor with immunoglobulin and ITIM domains), CTLA4 (cytotoxic T-lymphocyte-associated protein 4), TOX (thymocyte selection-associated high mobility group box protein), and Foxp3 (forkhead box P3) on circulating CD4 and CD8 T cells, along with production capacity of interferon-γ by lymphocytes following activation stimuli.

Results

Following administration of low-dose TSEBT and maintenance of the other therapies, remissions ranged from 24 to 30 months, with complete responses in 2 patients ongoing. Markers of immune exhaustion including PD-1, TIGIT, CTLA4, TOX, and Foxp3 were significantly reduced from baseline following TSEBT, along with enhanced production capacity of interferon-γ by lymphocytes following activation stimuli. High throughput sequencing demonstrated near-complete eradication of the circulating clone among 2 of 3 patients with stable levels in 1.

Conclusions and Relevance

We describe 3 patients who achieved long-term clinical and molecular remissions following low-dose TSEBT as part of a multimodality regimen for treatment of SS. As long-term remissions in SS are uncommon, this approach demonstrates promise, and clinical trials should be considered.

Prospective observational trial of low-dose skin electron beam therapy in mycosis fungoides using a rotational technique

INTRODUCTION

Low-dose total skin electron beam therapy provides a durable treatment response for skin lesions caused by cutaneous T-cell lymphoma. We prospectively assessed the durability of response and quality of life for patients receiving low-dose total skin electron beam therapy using a novel rotational technique and dosing regimen.

METHODS

Patients completed baseline Skindex-29 quality-of-life surveys and had baseline Modified Severity-Weighted Assessment Tool score recorded. Patients received 12 Gy in 12 fractions with a dual-field rotational technique. The primary outcome was overall response rate, with the secondary outcomes being time to treatment response, duration of clinical benefit, and quality-of-life change.

RESULTS

We enrolled 20 patients and recorded an overall response rate of 90%. The median time to treatment response was 6.5 weeks. The baseline Modified Severity-Weighted Assessment Tool score was 55.6 and it declined to a median of 2.2 at last follow-up (P < .001). The median duration of clinical benefit was 21 months. There was a decline in the Skindex-29 total score and every subdomain when each follow-up visit was compared (P = .004).

CONCLUSIONS

This prospective study demonstrated a very high overall response rate and improvement in skin-related quality of life. Low-dose rotational total skin electron beam therapy can be implemented routinely in clinical practice.

Skin colonization by circulating neoplastic clones in cutaneous T-cell lymphoma

Mycosis fungoides (MF) is a mature T-cell lymphoma currently thought to develop primarily in the skin by a clonal expansion of a transformed, resident memory T cell. However, this concept does not explain the key characteristics of MF, such as the debut with multiple, widespread skin lesions or inability of skin-directed therapies to provide cure. The testable inference of the mature T-cell theory is the clonality of MF with respect to all rearranged T-cell receptor (TCR) genes. Here, we used a whole-exome sequencing approach to detect and quantify TCR-α, β, and γ clonotypes in tumor cell clusters microdissected from MF lesions. This method allowed us to calculate the tumor cell fraction of the sample and therefore an unequivocal identification of the TCR clonotypes as neoplastic. Analysis of TCR sequences from 29 patients with MF stage I to IV proved the existence of multiple T-cell clones within the tumor cell fraction, with a considerable variation between patients and between lesions from the same patient (median, 11 clones; range, 2-80 clones/sample). We have also detected multiple neoplastic clones in the peripheral blood in all examined patients. Based on these findings, we propose that circulating neoplastic T-cell clones continuously replenish the lesions of MF, thus increasing their heterogeneity by a mechanism analogous to the consecutive tumor seeding. We hypothesize that circulating neoplastic clones might be a promising target for therapy and could be exploited as a potential biomarker in MF.

In vivo monitoring of total skin electron dose using optically stimulated luminescence dosimeters

AIM

This study retrospectively analysed the results of using optically stimulated radiation dosimeters (OSLDs) for in vivo dose measurements during total skin electron therapy (TSET, also known as TSEI, TSEB, TSEBT, TSI or TBE) treatments of patients with mycosis fungoides.

BACKGROUND

TSET treatments are generally delivered to standing patients, using treatment plans that are devised using manual dose calculations that require verification via in vivo dosimetry. Despite the increasing use of OSLDs for radiation dosimetry, there is minimal published guidance on the use of OSLDs for TSET verification.

MATERIALS AND METHODS

This study retrospectively reviewed in vivo dose measurements made during treatments of nine consecutive TSET patients, treated between 2013 and 2018. Landauer nanoDot OSLDs were used to measure the skin dose at reference locations on each patient, as well as at locations of clinical interest such as the head, hands, feet, axilla and groin.

RESULTS

1301 OSLD measurements were aggregated and analysed, producing results that were in broad agreement with previous TLD studies, while providing additional information about the variation of dose across concave surfaces and potentially guiding future refinement of treatment setup. In many cases these in vivo measurements were used to identify deviations from the planned dose in reference locations and to identify anatomical regions where additional shielding or boost treatments were required.

CONCLUSIONS

OSLDs can be used to obtain measurements of TSET dose that can inform monitor unit adjustments and identify regions of under and over dosage, while potentially informing continuous quality improvement in TSET treatment delivery.

Total Skin Electron Beam Therapy for Mycosis Fungoides Revisited With Adjuvant Systemic Therapy

BACKGROUND

Although standard-dose total skin electron beam therapy (TSEBT) has been thought to provide the greatest clinical benefit for mycosis fungoides, recent studies have shown that low-dose TSEBT may also provide high rates of disease control.

MATERIALS AND METHODS

A retrospective chart review was conducted for patients receiving TSEBT for mycosis fungoides at a single institution from 2009 to 2017. Patients were evaluated for overall survival, progression-free survival, and duration of clinical benefit. Partial response was defined as any documented clinical regression of lesions, whereas complete response was defined as complete resolution of lesions.

RESULTS

Twenty patients were included in the study. Twelve patients received low-dose radiation (≤ 12 Gy), and 8 received standard-dose radiation (> 12 Gy). Response rate was 100% in both groups. The rate of complete response was 38% in the standard-dose group and 25% in the low-dose group. There was no difference in overall survival between the 2 groups (P = .84). There was also no difference in median progression-free survival (P = .95) or duration of clinical benefit (P = .95) between the 2 groups. Of low-dose patients, 33% received immediate systemic therapy, whereas 92% received adjuvant topical or systemic therapy. In the standard-dose group, only 25% received systemic adjuvant therapy, and 63% received adjuvant topical or systemic therapy.

CONCLUSION

Low-dose TSEBT with adjuvant therapy results in adequate symptom palliation, comparable to standard-dose TSEBT. Low-dose TSEBT should be considered a standard treatment option in this population.

Extensive Cutaneous T-Cell Lymphoma of the Feet Treated with High-Dose-Rate Brachytherapy and External Beam Radiation

Cutaneous T-cell lymphoma (CTCL) is a chronic, debilitating disease that has a severe impact on quality of life. We present a patient with multiple CTCL lesions on the bilateral feet, which impaired his ability to ambulate. His lesions on both feet were successfully treated with a total of 8 Gy in two fractions via high-dose-rate surface brachytherapy using the Freiburg Flap applicator. The deeper aspects of the bulkier lesions on the left foot were boosted with electron beam therapy. The radiation therapy was well tolerated, and the patient was able to regain his mobility after completing radiation therapy. To our knowledge, there are few reports utilizing brachytherapy in treating CTCL. Our case describes treatment of larger, more extensive CTCL lesions than previously reported.

Total Skin Electron Irradiation and Sequential Malignancies in Mycosis Fungoides Patients: Longitudinal Study

AIMS

To determine the role of total skin electron irradiation (TSEI) as a cause of second malignancies in mycosis fungoides patients.

MATERIALS AND METHODS

Mycosis fungoides patients referred to TSEI were followed in a longitudinal study. Other diagnosed malignancies were obtained after cross-matching with the Israel National Cancer Registry database.

RESULTS

Between 1974 and 2010, 197 patients were treated: 134 (68%) men, 63 (32%) women; mean age 58 ± 17years. Topical/systemic treatment was given to 134 (68%) patients. TSEI was given to 104 (68.9%) patients. Seven (4.6%) received sub-TSEI and 40 (26.5%) received focal electron irradiation fields. Forty-six (23%) patients did not receive radiotherapy. The second primaries rate was 6.7 times higher in male mycosis fungoides patients and 13.1 times higher in female mycosis fungoides patients than in the general Israeli population. Malignant melanoma developed in eight patients after radiotherapy, in one patient without irradiation. The skin-related cancer rate after irradiation versus no irradiation was higher (P = 0.018). Combination radiotherapy with psoralen + ultraviolet A and/or nitrogen mustard yielded 11 cases of skin cancer versus no cases without irradiation.

CONCLUSIONS

Mycosis fungoides patients have a high incidence of sequential malignancies. TSEI is associated with higher 'skin-related cancer' rates. Close longitudinal follow-up of mycosis fungoides patients is obligatory.

Combination of low-dose total skin electron beam therapy and subsequent localized skin electron beam therapy as a therapeutic option for advanced-stage mycosis fungoides

Electron beam therapy (EBT) is an established treatment for mycosis fungoides (MF), but evidence for the use of EBT in advanced cutaneous conditions is limited, and optimal scheduling of the regimen for such conditions remains unclear. We report the case of a 44-year-old woman diagnosed with MF with widespread cutaneous lesions, including multiple huge tumours in the craniofacial area. Low-dose total skin (TS)EBT and subsequent localized skin (LS)EBT achieved striking improvements in eruptions. Oral etretinate was also administered during therapy. Our experience implies that combined TSEBT and LSEBT may be worth attempting when a patient presents with both widespread lesions and prominent tumours, even when the tumours are extremely large.

Multidisciplinary Management of Mycosis Fungoides/Sézary Syndrome

PURPOSE OF REVIEW

Diagnosis and management of mycosis fungoides and Sézary syndrome (MF/SS) require accurate clinicopathological correlation and a multidisciplinary approach. We reviewed major advances in the field regarding diagnostic and prognostic tools as well as skin-directed therapies (SDTs) and systemic agents for MF/SS published in the past 2 years.

RECENT FINDINGS

Improved technology (T-cell receptor high-throughput sequencing) and increased multicenter collaboration (Cutaneous Lymphoma International Consortium) have led to diagnostic/prognostic advances. Concurrently, numerous genomic studies have enhanced understanding of disease pathogenesis. Advances in SDTs include topical resiquimod, a novel potent Toll-like receptor (TLR) agonist; consensus CTCL phototherapy guidelines; and use of low-dose radiation therapy. Novel systemic therapies for advanced disease of note include targeted antibody drug conjugates (brentuximab vedotin), immune checkpoint inhibitors, and allogeneic hematopoietic stem cell transplantation (HSCT). Our "toolbox" to diagnose and treat the spectrum of MF/SS continues to expand. Further characterization of genomic data going forward will enable a rational approach to selecting and combining therapies to improve patient care.

Annual Facility Treatment Volume and Patient Survival for Mycosis Fungoides and Sézary Syndrome

BACKGROUND

Management of mycosis fungoides and Sézary syndrome (MF/SS) is complex, and randomized evidence to guide treatment is lacking. The institutional treatment volumes for MF/SS might vary widely nationally and influence patient survival.

PATIENTS AND METHODS

Using the National Cancer Database, we identified patients with a diagnosis of MF/SS from 2004 to 2011 in the United States who had received treatment at a reporting facility. The patients were grouped into quintiles according to their treatment facility's average annual treatment volume (ATV). The characteristics associated with ATV were identified and compared using χ² tests. Overall survival (OS) was compared among the ATV quintiles using the Kaplan-Meier method with log-rank tests and multivariable Cox regression with hazard ratios (HRs). OS was also analyzed using the annual patient volume as a continuous variable.

RESULTS

A total of 2205 patients treated at 374 facilities were included for analysis. The ATV quintile cutoffs were 1, 3, 6, and 9 patients. With a median follow-up period of 59 months, the 5-year estimated OS survival increased with ATV from 56.7% in the lowest quintile (≤ 1 patient annually) to 83.8% in the highest quintile (> 9 patients annually; P < .001). On multivariable analysis, greater ATV was associated with improved survival when analyzed as a continuous variable (HR, 0.96 per patient per year; 95% confidence interval, 0.94-0.98; P < .001) and when comparing the highest quintile to the lowest quintile (HR, 0.46; 95% confidence interval, 0.39-0.55).

CONCLUSION

The present national database analysis demonstrated that higher facility ATV is associated with improved OS for patients with MF/SS. Further study is needed to determine the underlying reasons for improved survival with higher facility ATV.