Treatment Approach for Children and Adolescents with Hodgkin Lymphoma
By implication, when it is necessary to treat the pelvis, special attention must be given to the ovaries and testes. The ovaries should be relocated, marked with surgical clips, laterally along the iliac wings, or centrally behind the uterus in order to permit appropriate shielding. Ideally, the ovaries should be exposed to less than 3 Gy to preserve fertility. The testes may be incidentally exposed to 5% to 10% of the administered pelvic dose, which may be sufficient to cause transient azoospermia, depending on the total pelvic dose. Multileaf collimation or custom blocking should be used when feasible to block the primary beam; scatter dose to the testes can be minimized with the patient treated in a frog-legged position with a "clamshell" testicular shield. In a very young child (younger than age 5 years), consideration may be given to treating bilateral areas (e.g., both sides of the neck) to avoid growth asymmetry. Growth asymmetry, however, is less of a concern with low radiation doses; unilateral fields are usually appropriate if the disease is unilateral.
Field definition for radiation therapy in unfavorable and advanced Hodgkin lymphoma is variable and protocol dependent. Although IFRT remains the standard when patients are treated with combined modality therapy, restricting radiation therapy to areas of initial bulk disease (generally defined as ?5 cm at the time of disease presentation) or postchemotherapy residual disease (generally defined as ?2 cm or more, or residual positron emission tomography [PET] avidity), is under investigation. The rationale for this is to limit radiation exposure to large portions of the body in patients who often have multifocal disease, including organ invasion. Large-volume radiation therapy can compromise organ function and may limit the intensity of retrieval therapy if relapse occurs. However, as previously stated, the current standard of therapy does include postchemotherapy IFRT for patients with intermediate or advanced disease based on data from the Children's Cancer Study Group  and the German-Austrian Childhood Hodgkin studies.
An example of definitions for IFRT is shown in the following table (Table 2), with more restricted definitions increasingly common and protocol-specific.
Table 2. Sample Definitions of Sites and Corresponding Radiation Treatment Fieldsa
a Adapted from Hudson.
b Upper cervical region not treated if supraclavicular involvement is extension of the mediastinal disease.
c Prechemotherapy volume is treated except for lateral borders of the mediastinal field, which is postchemotherapy.
| Involved Node(s)||Radiation Field|
|Cervical||Neck and infraclavicular/supraclavicularb|
|Supraclavicular||Neck and infraclavicular/supraclavicular � axilla|
|Axilla||Axilla � infraclavicular/supraclavicular|
|Mediastinum||Mediastinum, hila, infraclavicular/supraclavicularb,c|
|Spleen||Spleen � para-aortics|
|Para-aortics||Para-aortics � spleen|
|Iliac||Ipsilateral iliac � inguinal + femoral|
|Inguinal||Inguinal + femoral � iliac|
|Femoral||Inguinal + femoral � iliac|
The dose of radiation is also variously defined and often protocol-specific. In general, doses of 15 Gy to 25 Gy are used, with modifications based on patient age, the presence of bulk or residual (postchemotherapy) disease, and normal tissue concerns. In some situations, a boost of 5 Gy is appropriate. The dose may be determined by the response obtained to initial combination chemotherapy. In most trials conducted before 1995, patients achieving a complete response (CR) to initial chemotherapy received LD-IFRT (15-25 Gy). In some studies, patients with partial responses (PR) received higher radiation doses.