Radiotherapy in the management of mycosis fungoides: indications, results, prognosis. Twenty years experience

Electron radiation therapy: Back to the future?

Electron radiotherapy has long been preferred to photons for the treatment of superficial lesions because of its physical characteristics (high dose at the surface, rapid decrease in depth). Other characteristics (penumbra, heterogeneity on an oblique or irregular surface) make them difficult to use. In most indications (skin cancers, head and neck, medulloblastoma), with technical progress, in some cases they have been replaced by intensity-modulated conformal radiotherapy, brachytherapy and contact therapy. Other indications (drainage of mesotheliomas or irradiation of benign lesions) have disappeared. The low frequency of use leads to problems of safety and cost-effectiveness. However, modern photon radiotherapy techniques are still less effective than electrons in specific indications such as total skin irradiation (mycosis fungoides) or certain thin chest wall irradiations after total mastectomy, reirradiation or paediatric treatments without protons. Flash therapy, initiated by electrons, has been developed over the last 10 years, providing high-dose irradiation in an extremely short time. Initial results show good efficacy, with fewer side effects than with conventional radiotherapy. These results are leading to clinical technological developments on a larger scale. Although it has been replaced in most indications by more modern techniques, electron radiotherapy remains essential for targeted indications in specialised centres. The emergence of flash therapy will lead to new indications, on machines equipped with this new technology, which have yet to be defined and are currently the responsibility of specialised teams.

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.

Ultraviolet-B Phototherapy Is Successful in Japanese Patients with Early-Stage Mycosis Fungoides

UVB phototherapy is widely used for the treatment of psoriasis and atopic dermatitis, however, only limited reports evaluate its usefulness in the treatment of mycosis fungoides. We introduced UVB phototherapy to five patients with early-stage mycosis fungoides. All of them were classified as stage IB (erythematous stage), and none had obtained a satisfactory response to other therapies. After initial treatment with UVB phototherapy, all the patients obtained significant improvement in their skin lesions leaving pigmentary changes. After this satisfactory response was achieved, the same dose of UVB was administrated as a maintenance therapy with longer intervals between exposures. Histopathological examination of three patients revealed decreased numbers of inflammatory cells in both the epidermis and the dermis after the treatment. Immunohistochemical study showed that CD1a+/HLA-DR+ dendritic cells were present throughout the lesional epidermis before the treatment. In contrast, after the treatment, the dendritic cells in the epidermis were CD1a+/HLA-DR-. Although it remains unclear why only the expression of HLA-DR antigen was eliminated after treatment, we presume that this loss of HLA-DR antigen expression by epidermal Langerhans cells was, in part, responsible for the improvement of skin lesions. This preliminary study suggests that UVB phototherapy is an effective treatment for patients with early-stage mycosis fungoides.

Technical and dosimetric aspects of the total skin electron beam technique implemented at Heidelberg University Hospital

AIM

To give a technical description and present the dosimetric proporties of the total skin electron beam technique implemented at Heidelberg University Hospital.

BACKGROUND

Techniques used for total skin electron beam irradiation were developed as early as in the 1960s to 1980s and have, since then, hardly changed. However, new measurements of the established methods allow deeper insight into the dose distributions and reasons for possible deviations from uniform dose.

MATERIALS AND METHODS

The TSEI technique applied at Heidelberg University Hospital since 1992 consists of irradiating the patient with a superposition of two beams of low energy electrons at gantry angles of 72° and 108° while he is rotating in a standing position on a turntable at 370 cm distance from the accelerator. The energy of the electron beam is degraded to 3.9 MeV by passing through an attenuator of 6 mm of Perspex. A recent re-measurement of the dose distribution is presented using modern dosimetry tools like a linear array of ionization chambers in combination with established methods like thermoluminescent detectors and film dosimetry.

RESULTS

The measurements show a strong dependence of dose uniformity on details of the setup like gantry angles.

CONCLUSIONS

Dose uniformity of -4/+8% to the majority of the patient's skin can be achieved, however, for the described rotational technique overdoses up to more than 20% in small regions seem unavoidable.

Literature review of clinical results of total skin electron irradiation (TSEBT) of mycosis fungoides in adults

BACKGROUND

Mycosis fungoides (MF) is an extranodal, indolent non-Hodgkin lymphoma of T cell origin. Even with the establishment of MF staging, the initial treatment strategy often remains unclear.

AIM

The aim of this study was to review the clinical results of total skin electron beam therapy (TSEBT) for MF in adults published in English language scientific journals searched in Pubmed/Medline database until December 2012.

RESULTS

MF is very sensitive to radiation therapy (RT) delivered either by photons or by electrons. In limited patches and/or plaques local electron beam irradiation results in good outcomes besides the fact of not being superior to other modalities. For extensive patches and/or plaques data suggest that TSEBT shows superior response rates. The cutaneous disease presentation is favorably managed with radiotherapy due to its ability to treat the full thickness of deeply infiltrated skin. For generalized erythroderma presentation, TSEBT seems to be an appropriate initial therapy. For advanced disease, palliation, or recurrence after the first radiotherapy treatment course, TSEBT may still be beneficial, with acceptable toxicity. Recommended dose is 30-36 Gy delivered in 6-10 weeks.

CONCLUSION

TSEBT can be used to treat any stage of MF. It also presents good tumor response with symptoms of relief and a palliative effect on MF, either after previous irradiation or failure of other treatment strategies.

Efficacy and tolerability of currently available therapies for the mycosis fungoides and Sezary syndrome variants of cutaneous T-cell lymphoma

Primary cutaneous T-cell lymphomas are a heterogenous group of non-Hodgkin lymphomas. The characteristic clinicopathologic and immunophenotypic features and prognoses of the various cutaneous lymphomas have been recently described by the World Health Organization and European Organization for Research and Treatment of Cancer. Cutaneous T-cell lymphoma variants include mycosis fungoides and Sezary syndrome, which are generally associated, respectively, with indolent and aggressive clinical courses and are the subject of this review. Currently utilized treatments for cutaneous T-cell lymphoma include skin-directed therapies (topical agents such as corticosteroids, mechlorethamine, carmustine, and retinoids, phototherapy, superficial radiotherapy, and total skin electron beam therapy), systemic therapies (photophoresis, retinoids, denileukin diftitox, interferons, and chemotherapy), and stem cell transplantation (autologous and allogeneic). This review will describe recent advances in our understanding of the biology (immunologic, cytogenetic, and genetic) of cutaneous T-cell lymphomas and discuss the efficacy and tolerability of the current therapeutic options for cutaneous T-cell lymphomas. Disease progression in over 20% of patients with early stages of disease and the current lack of a definitive treatment which produces durable responses in advanced stages of disease indicates a critical unmet need in CTCL. New insights into the molecular and immunologic changes associated with cutaneous T-cell lymphomas should ultimately lead to the identification of novel therapeutic targets and the development of improved therapeutic options for patients with these malignancies.

Matching the dosimetry characteristics of a dual-field Stanford technique to a customized single-field Stanford technique for total skin electron therapy

PURPOSE

To compare the dosimetry characteristics of a customized single-field and a matching dual-field electron beam for total skin electron therapy (TSET) within the framework of the Stanford technique. To examine and quantify its impact on patient dosimetry.

METHODS AND MATERIALS

Two characteristically different electron beams were used for TSET employing the Stanford technique: a single-field beam created from a pencil beam of electrons passing through 7 meters of air and a dual-field beam created from two heavily scattered electron beams directed at oblique angles to patients. The dosimetry characteristics of the two beams were measured by using ionization chambers, radiographic films, and thermal luminescent detectors. The impact of beam characteristic on patient dosimetry was quantified on both anthromorphic phantoms and on patients. Treatment protocols aimed at matching the patient dose between the two systems were established on the basis of these and other measurements.

RESULTS

The dual-field beam was matched to the single-field beam, resulting in approximately the same mean energy (approximately 4.0 MeV) and most probable energy (approximately 4.5 MeV) at their respective treatment source-to-patient-surface distance (SSD). The depth dose curves on the beam axis were nearly identical for both beams. X-ray contamination on the beam axis was 0.43% for the dual-field beam, slightly higher than that (0.4%) of the single-field beam. The beam uniformity, however, was quite different: the dual-field beam was more uniform in the vertical direction but was worse in the lateral direction compared to the single-field beam. For a TSET treatment using the Stanford technique, the composite depth dose curves were nearly identically at the level of beam axis: with an effective depth of maximum buildup (d(max)) at approximately 1 mm below the skin surface and the depth to 80% depth dose at around 6 mm. The overall X-ray contamination was approximately 1.0% and 1.2% for the single-field and dual-field system, respectively. Away from the beam axis level, treatment using either beam was able to deliver over 90% of prescription dose to the main body surfaces. For body surfaces tangential to the beam axis (e.g., top of head and shoulders), the dose was low especially when using the dual-field beam. By adding boost radiation to the tangential surfaces and by adjusting the planned shielding for critical structures, the total dose to the patient over a complete course of TSET treatment could be matched closely for the two systems.

CONCLUSIONS

Although the depth doses can be matched at the level of the beam axis, there exist some characteristic differences in the angular distribution of the electrons between the large SSD single-field beam and the short SSD dual-field beam. These differences resulted in lower dose delivered to "tangential" body surfaces and to body structures that extended farther laterally when using the dual-field beam. However, by adjusting the treatment protocol regarding the boost irradiation and planned shielding, the total dose to patients from a complete course of TSET treatment using the dual-field beam can be matched to that given by the single-field beam. Special attention should be paid to the dosimetry at the "tangential" body surfaces when commissioning a dual-field TSET system.

Total skin electron beam radiotherapy for patients who have mycosis fungoides

It has taken four decades of basic and clinical research to bring about a consensus process and published report that recognize a TSEB radiotherapy technique that is optimized from several perspectives (see references [2-4, 13]). Short and long-term clinical results with consensus TSEB radiotherapy technique are good. The therapeutic ratio of TSEB radiotherapy is well-defined and is clinically acceptable. Meanwhile, adjuvant PUVA and ECP may significantly improve results, but further data are needed to confirm these preliminary findings (see references [23, 34, 39, 40, 42]).

Total skin electron irradiation in mycosis fungoides: comparison between a modified Christie Hospital translational technique and the Stanford technique

Seventy-one patients with mycosis fungoides (MF) were treated by Total skin electron irradiation (TSEI) using either a modified Christie Hospital translational technique (44 pts) or a six dual-field Stanford technique (27 pts). There was no statistical difference in response rate, disease-free survival and overall survival between the two irradiation techniques. However, the Stanford technique was significantly less toxic than the modified Christie Hospital technique.

Cutaneous T-cell lymphoma treated with electron beam irradiation in Indian patients

BACKGROUND

Cutaneous T-cell lymphoma (CTCL) is a rare occurrence in India. Total skin electron irradiation (TSEI) is a well-accepted therapeutic modality for the treatment of CTCL throughout the world. The aim of this study was to retrospectively analyze the treatment outcome of TSEI in Indian patients with CTCL and to determine the different parameters affecting the disease-free survival in these patients.

METHODS

Fourteen male patients between 27 and 82 years of age with CTCL (duration of disease, 4 months to 2 years) were treated with TSEI between 1985 and 1998. Seven patients had early stage disease, while the other seven had advanced disease. Two patients had lymph node involvement at the time of presentation. The TSEI was performed according to the Stanford technique delivering a total dose in the range 8-36 Gy.

RESULTS

Of the 14 patients, 10 showed complete remission following TSEI. The total follow-up period was 4-110 months (median, 52 months). Five patients were disease free at the end of 5 years. Two patients died due to rapid progression of the disease, while the cutaneous lesions relapsed in three patients after 2-27 months and one patient developed visceral metastasis.

CONCLUSIONS

TSEI was an effective therapeutic modality for the treatment of CTCL in this group of patients, both as a curative and palliative measure, although the long-term prognosis is poor.

Dosimetry of rotational partial-skin electron irradiation

BACKGROUND AND PURPOSE

Often, the most appropriate treatment for superficially and extensively spreading tumors of the skin is to use electron irradiation at enlarged distances. Rotational skin electron irradiation is a proven method for the treatment of the entire skin surface. We here report modifications of this technique in the set-up of partial-skin electron irradiation and the results of dosimetric examinations with regard to optimal shielding, dose profiles and depth dose curves under various irradiation conditions.

MATERIALS AND METHODS

Irradiation was performed using electron beams with nominal energies of 6 MeV from a linear accelerator. The phantom was located on a rotating platform at a source-surface distance SSD=300 cm. A horizontal slit aperture (height: 32 cm) within a 2 cm thick polymethylmethacrylate (PMMA) shielding plate near the phantom was used to define the size of the irradiated region. Influences on dose distributions due to scattering processes on the PMMA edges were investigated using a flat ionization chamber and films. Absolute dose measurements and film calibration were made with the flat chamber. The quality of bremsstrahlung radiation behind the shielding was determined with a thimble ionization chamber in the phantom.

RESULTS AND CONCLUSIONS

The results of rotational partial-skin electron irradiation reveal some of the investigated shielding geometries to be optimal. Depth dose distributions and dose rates correspond to the results obtained in total skin electron rotational irradiation. It is possible to apply the dose superficially in the first millimeters of the skin; the dose maximum is located at a depth of 0-2 mm, the 80% isodose at 9 mm. The amount of bremsstrahlung contamination is 2.5%. The local amount of absorbed dose per monitor unit depends strongly on patient/phantom cross-section geometry. At our institute, rotational partial-skin electron irradiation was implemented into clinical routine in 1997.

Radiotherapy in the management of cutaneous B-cell lymphoma. Our experience in 25 cases

PURPOSE

To report our results in the treatment with radiation therapy of 25 patients affected by B-cell lymphoma with initial cutaneous presentation.

MATERIALS AND METHODS

From October 1978 to June 1997, we have treated 25 patients with cutaneous B-cell lymphoma (CBCL) by cutaneous irradiation. There were 17 males and eight females, aged from 23 to 89 years (median age 50 years). The mean follow-up time for the series was 3.9 years (range from 0.2 to 15 years) from the completion of radiation therapy. All patients were staged as follows: in group 1, single lesion; group 2, multiple lesions; group 3, disseminated lesions. There were six (24%) patients in group 1, 15 (60%) patients in group 2, and four (16%) in group 3. There were nine patients with head and neck lesions, 11 patients with trunk lesions, and five patients with leg lesions. Thirteen patients (52%) had previously received chemotherapy for CBCL. Extended field irradiation was used to treat six patients (24%). Localized field irradiation (LFI) was performed for the other 19 patients (76%).

RESULTS

The overall survival rate at 5 years was 73%. The complete response (CR) to the treatment for our series was 92%. The length of complete remission ranged from 2 to 180 months. There were three patients (8%) who obtained partial response (PR). Disease-free survival (DFS) at 1 year was 91% and at 5 years was 75%. Radiotherapy was generally well tolerated.

CONCLUSIONS

Localized field irradiation is an effective treatment for some localized forms of primary cutaneous B-cell lymphoma and can obtain prolonged remissions. The patients with wide-spread skin involvement are usually candidates for extended field irradiation and/or chemotherapy. For the advanced stages of cutaneous B-cell lymphoma, where the chemotherapy is the treatment of choice, some good palliation can be achieved using local field irradiation.