Low-dose volumetric modulated arc therapy for a patient with mycosis fungoides head and neck involvement: a case report with literature review

Mycosis fungoides (MF) is the most common type of cutaneous T-cell lymphoma that grows slowly over a period of years to decades. In some cases, lesions that spread to the scalp, neck, or facial skin can have a significant impact on the patient’s aesthetic appearance and quality of life. Among the various treatments, radiation therapy is one of the most effective treatment modalities for patients with symptomatic skin lesions. We report the case of a patient with MF who presented with progressively increasing patches and plaques on the scalp, face and neck who underwent 20 Gy irradiation administered in 10 fractions using the modulated volumetric arc therapy. After undergoing this highly compliant technique, the patient achieved prolonged local control and significant symptom relief with acceptable adverse events. This technique is a promising approach for the treatment of a complex target due to its ability to provide homogeneous coverage of irregularly shaped target volumes as well as its ability to preserve organs at risk. In addition, we systematically reviewed clinical reports on the management of extensive skin lesions in patients with MF undergoing other radiation techniques.

Introduction

Although mycosis fungoides (MF) is a rare disease with a relatively good prognosis when treated at an early stage, extensive skin lesions can impair a patient’s quality of life (QOL). [1-4]. Radiation therapy is one of the most effective treatment modalities for patients with MF at all stages, including symptomatic skin lesions [5-7]. When skin lesions are solitary or few in number, local radiation therapy with electron or photon beam irradiation is usually indicated, while total skin electron beam therapy (TSEBT) is required when skin lesions are present. extend over the whole body. [5-7]. However, when the skin lesions extend widely to uneven areas and with curved surfaces, such as the face and neck, these cases require advanced techniques of electron beam irradiation, which pose various challenges such as the heterogeneity of the target volume as well as the long processing time [8-10]. In order to homogenize targeted lesions with complex shapes and subjects subject to strict dose constraints for the organs at risk, new irradiation techniques have been developed. These new methodologies include Intensity Modulated Radiation Therapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT), with these techniques now being used in daily clinical practice for advanced head and neck cancer and brain tumors. . [11, 12]. This report presents data for successful clinical treatment of extensive MF on the scalp, face, and neck using VMAT with 20 Gy administered in 10 fractions.

Presentation of the case

An 82-year-old man presented with a tumor in the posterior atrial region and a three-year history of erythematous patches and plaques on the trunk, extremities, and face. A skin biopsy of a thoracic skin lesion was performed and histological evaluation of the specimen revealed the infiltration of atypical lymphocytes in the epidermis, which was positive for CD3, CD4 and CD5, and negative for CD79a, CD8 and CD20 (L26) . Atypical lymphocytes were not observed in peripheral blood. Serum soluble interleukin-2 receptor was elevated at 848 U/mL, and antibodies to human T-cell leukemia virus 1 and 2 were not detected.

The patient was diagnosed with MF T3N0M0B0 Stage2B according to the revised classification system of the International Society for Cutaneous Lymphoma/European Organization for Research and Treatment of Cancer (ISCL/EORTC). Although he was treated with chemotherapy (bexarotene) and skin-directed therapies such as topical agents and phototherapy, the skin lesions became resistant to these therapies and side effects such as renal failure and hypertriglyceridemia made it difficult to administer adequate doses of chemotherapy. The patches and plaques gradually increased, mainly on the facial skin and scalp, and this appearance of skin lesions such as erythema and alopecia impaired the patient’s quality of life (Figure 1A, 1B). The patient had no history of radiation therapy and was transferred to radiation therapy using VMAT.

Computed tomography (CT) simulation was performed in the supine position at a slice thickness of 2 mm. After immobilizing the subject using an S-Cup (Toyo Medic), a 0.5 cm bolus was placed to fit the patient, with a second S-Cup then immobilized over the bolus ( figure 2). The VMAT plan was created using the Pinnacle version 9.10 treatment planning system (Philips). The clinical target volume (CTV) included a 4 mm area from the skin surface of the entire scalp and face to the neck. The planning target volume (PTV) was defined as the CTV plus a margin of 5 mm. The PTV was cut by a margin of 3 mm from the skin surface to form the PTV evaluation structure (PTVeval), which was used for dose normalization. A dose of 20 Gy in 10 fractions was prescribed at the average dose of the PTVeval using a 6 MV photon beam from Versa HD (Elekta). The VMAT plane was designed by 3 arc rotation fields to deliver a highly conformal dose distribution to the target with complex shapes, while minimizing the dose delivered to organs at risk such as the brain and parotid glands. The lenses and lacrimal glands were not spared due to eyelid involvement. Figure 3 shows the dose distribution and the dose-volume histogram of the VMAT plan. The irradiation time was 555 seconds, with a total time from when the patient entered the treatment room to when they left, approximately 20 minutes. Toxicity assessment was defined with the CTCAE v5 scale. Radiation therapy was performed in combination with the administration of low dose bexarotene to control skin lesions outside the irradiated area, with no adverse events observed during the treatment period. One week after the end of radiotherapy, the patient presented with grade 1 radiation dermatitis, grade 2 alopecia and mild dilatation of the subcutaneous veins, with less erythematous skin lesions and no bone marrow suppression (Picture 1 C, 1D). Two months after the end of the radiotherapy, the skin lesions had almost completely disappeared, although there was still slight redness in some places. Four months after the end of radiotherapy, a complete response (CR) was observed for the skin lesions and the patient’s normal hair had grown back (Figure 1E, 1F). At 16 months from the completion of radiation therapy, CR remained for lesions in the irradiated area, and there were no observed late adverse events resulting from the administered radiation.

Patient immobilization device
Volumetric modulation arc therapy plan

Discussion

MF is a peripheral T-cell lymphoma that primarily affects the skin and is often treated with local electron beam irradiation or TSEBT [5-7]. However, with recent advances in irradiation techniques, the effectiveness of total scalp irradiation using IMRT, VMAT, or total cutaneous helical tomotherapy (TSHT) has been reported. [13-17]. In addition, these new irradiation techniques have made it possible to deliver uniform doses to complex-shaped skin surfaces, thus sparing adjacent normal tissues and critical structures. [14-17]. Additionally, these treatments require less treatment time and can be performed while lying down, which can help reduce patient burden compared to that associated with the use of complex electron beam irradiation.

Additionally, some authors have reported good outcomes for cutaneous T-cell lymphoma of the scalp when using IMRT treatments, in conjunction with clinically acceptable adverse events. [13-15]. Although efficacy of TSHT has also been reported in several cases, photon beams are more likely to cause severe bone marrow suppression than electron beams due to the increased dose delivered to the deeper parts. from the body. [16-19]. One death due to TSHT-associated bone marrow suppression has previously been reported [18].

In addition, patients with MF have also been reported to develop bone marrow suppression, including grade 4 thrombocytopenia after TSHT despite administration of such low mean bone marrow doses (arm not included). than 1.66 and 2.3 Gy, respectively. [19]. In our patient, although the lesion had also spread to the trunk, we decided to use VMAT only to treat the skin of the head, face and neck, as irradiation over a wider area could potentially cause bone marrow suppression, with increases in scalp and facial lesions also reducing quality of life. Even at the lower dose of 20 Gy previously reported, we were able to achieve relatively long-term local control, and moreover, with the additional application of VMAT to the local lesions, there were minimal adverse effects as well as high patient satisfaction. [5-7].

The advantages of treating our current case with VMAT were the shorter treatment times, less laborious setup, and high dose-to-target homogeneity. These results suggest that this approach can be used to treat patients with other cutaneous malignancies that include extensive spread of lesions to the scalp and face.

conclusion

MF is a highly radiosensitive disease and radiation therapy plays an important role in the management of patients at all stages of MF. VMAT can deliver a highly target-consistent dose with complex shapes, while minimizing the dose delivered to organs at risk. For MF with extensive lesions ranging from the skin of the scalp to the face and neck, low dose radiotherapy with VMAT has been shown to be very helpful and has led to excellent local control with little toxicity.

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