Radiation therapy techniques in the treatment of Hodgkin's disease

[Hodgkin's Lymphoma]

With approximately 1500 cases per year in France, Hodgkin's lymphoma (HL) represents only 10 to 15 % of new cases of lymphomas, and 0.5 to 1 % of new cases of cancers. The management of this lymphoproliferative disease has undergone profound conceptual changes over time, allowing at present to obtain a cure rate of 75 to 80 % of all confused stage, and up to 90 % in case of early stage HL. If initial treatment consisted in an exclusive extensive (total or sub-total lymphoid) irradiation whatever the stage may be, the place of radiotherapy in the management of HL has evolved over time but remains today one of the cornerstones of the treatment. It becomes integrated within the framework of combined modality therapies associating chemotherapy then irradiation for the early stage HL, and stays a therapeutic alternative in all situations (in advanced stage and\or recurrent disease) which raises the issue of increasing the locoregional tumor control. Despite the undeniable contribution of radiotherapy in controlling the disease, delayed side effects of treatments are not negligible. So the long-term monitoring of treated patients is essential, mainly because of an increased risk of morbi-mortality due to cardiovascular events and/or secondary cancers. It is important to remember that even today the "Involved Field" irradiation type remains the gold standard, even if we witness at present the emergence of new types of irradiation, which aim to reduce the amount of irradiated tissues to try to limit the risks of delayed radio-induced complications. The purpose of this article is to clarify the specific aspects (epidemiological, radio-anatomical and prognostic characteristics) of HL, as well as the practical modalities of the irradiation (illustrated by a clinical case record) when an indication of radiotherapy is placed for its treatment.

[Hodgkin's disease: from gross tumor volume to clinical target volume, firm data and unresolved problems]

The purpose of this article is to specify the target volumes, using ICRU criteria in the treatment of Hodgkin's disease. Because of the complexity of irradiation fields, the literature was carefully reviewed. However, with the variations of the recommendations and in the absence of large-scale studies, usual criteria can still be used. A consensus about the precise specification of the target volumes on CAT scan is still urgently awaited.

Active breathing control (ABC) for Hodgkin's disease: reduction in normal tissue irradiation with deep inspiration and implications for treatment

PURPOSE

Active breathing control (ABC) temporarily immobilizes breathing. This may allow a reduction in treatment margins. This planning study assesses normal tissue irradiation and reproducibility using ABC for Hodgkin's disease.

METHODS AND MATERIALS

Five patients underwent CT scans using ABC obtained at the end of normal inspiration (NI), normal expiration (NE), and deep inspiration (DI). DI scans were repeated within the same session and 1-2 weeks later. To simulate mantle radiotherapy, a CTV1 was contoured encompassing the supraclavicular region, mediastinum, hila, and part of the heart. CTV2 was the same as CTV1 but included the whole heart. CTV3 encompassed the spleen and para-aortic lymph nodes. The planning target volume (PTV) was defined as CTV + 9 mm. PTVs were determined at NI, NE, and DI. A composite PTV (comp-PTV) based on the range of NI and NE PTVs was determined to represent the margin necessary for free breathing. Lung dose-mass histograms (DMH) for PTV1 and PTV2 and cardiac dose-volume histograms (DVH) for PTV3 were compared at the three different respiratory phases.

RESULTS

ABC was well-tolerated by all patients. DI breath-holds ranged from 34 to 45 s. DMHs determined for PTV1 revealed a median reduction in lung mass irradiated at DI of 12% (range, 9-24%; n = 5) compared with simulated free-breathing. PTV2 comparisons also showed a median reduction of 12% lung mass irradiated (range, 8-28%; n = 5). PTV3 analyses revealed the mean volume of heart irradiated decreased from 26% to 5% with deep inspiration (n = 5). Lung volume comparisons between intrasession and intersession DI studies revealed mean variations of 4%.

CONCLUSION

ABC is well tolerated and reproducible. Radiotherapy delivered at deep inspiration with ABC may decrease normal tissue irradiation in Hodgkin's disease patients.

Dose distribution throughout the body from radiotherapy for Hodgkin's disease in childhood

BACKGROUND AND PURPOSE

The individual dosimetry performed for a multicentre European cohort study of second malignant neoplasm following radiotherapy for a solid cancer in childhood demonstrated a large variation in the radiation doses estimated to any site.

MATERIALS AND METHODS

From this study we have extracted the present work, i.e. estimation of doses for patients who underwent radiotherapy for Hodgkin's disease in their childhood. These patients were treated using high energy X-rays from linear accelerators (MV group), gamma-radiation from Cobalt machines (Cobalt group), soft X-rays from orthovoltage machines (kV group) and electron beams from accelerators (MeV group) at six French and UK centres. All patients started their radiotherapy between 1955 and 1985 and about 12% of them received more than one beam quality. Most of the patients were irradiated with large mantle AP/PA or partial mantle fields. Patients with transdiaphragmatic extension were also irradiated using inverted-Y paraaortic fields. The absorbed doses at the 91 skeleton points are used to calculate the mean dose to the active bone marrow.

RESULTS

Estimates of the median and mean doses, standard deviations and ranges to 13 specific sites of the body and to the active bone marrow are reported. Depending upon the size and sex of patients, target volume and position and radiotherapy techniques, the estimated doses are highly spread, attaining 0.19-106.07% of the target dose. This study underscores the need for individual dosimetry in epidemiological studies. Comparison with the available measured and calculated doses to the ovary and testis shows good agreement.

CONCLUSION

This study underscores the need for individual dosimetry in epidemiological studies.

Radiation techniques for the treatment of Hodgkin's disease with combined modality therapy or radiation alone

This article reviews radiation techniques including field arrangements, anatomic borders, and doses for the treatment of Hodgkin's disease when radiotherapy is being used as the sole treatment and when it is part of a planned combined modality program with chemotherapy. We describe the techniques currently in use at Duke University Medical Center. Particular emphasis is placed on the evidence regarding the appropriate extent of the treatment field and the doses of radiation necessary to achieve local control. These issues assume increasing importance as we attempt to maintain high cure rates for Hodgkin's disease but lower the frequency of serious long-term complications.