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Hodgkin lymphoma is a hematopoietic
malignancy with unique epidemiologic features that vary depending
on the geographic region of the patient. Genetic and environmental
contributions to the pathogenesis of the disease are not completely
understood and represent an active area of research. Progression
of Hodgkin lymphoma initially occurs along functionally contiguous
lymph nodes. If untreated, extranodal involvement eventually results
from hematogenous dissemination of neoplastic cells to the liver,
lungs, bones, bone marrow, and other tissues. The most common clinical
presentation is one of painless lymphadenopathy previously attributed
to infectious or inflammatory etiologies. Other signs and symptoms
vary based on the involved nodal sites and their compression of
adjacent organs and tissues. Cytokine production by malignant cells
results in constitutional symptoms including anorexia, pruritus, weight
loss, night sweats, and fever in some patients.
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Providing care for children with Hodgkin lymphoma challenges
the pediatric and radiation oncology team to accomplish the tandem
goals of optimizing disease control and limiting long-term morbidity.1 Historically,
treatment approaches mirrored those used for adults, but outcome
was compromised by unacceptable musculoskeletal hypoplasia resulting
from high dosage radiation of large volumes in physically immature
children. Pediatric patients are also more likely to experience
cardiovascular toxicity associated with anthracycline chemotherapy
and thoracic radiation, which may predispose them to early mortality
associated with cardiomyopathy and coronary artery disease.2 There
are also specific gender-related predispositions to treatment effects.
Boys are more vulnerable to gonadal toxicity following cumulative
doses of alkylating agent chemotherapy used in primary treatment regimens,
whereas girls generally maintain ovarian function unless chemotherapy
is combined with infradiaphragmatic radiation. Conversely, girls
treated with anthracycline chemotherapy, particularly if younger
than age 5 years, are more likely than boys to experience cardiotoxicity.
Likewise, young women treated with thoracic radiation during puberty
have a substantially increased risk of a breast malignancy that
is not observed in their male counterparts.3 Because of
these unique developmental and gender-related predispositions to
therapy effects, there is no single treatment method that is ideal
for all patients. Contemporary treatment uses a risk-adapted approach
that considers the prognostic features of the disease presentation
in the context of a patient’s predisposition to long-term
toxicity related to age and gender.
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Etiology and Epidemiology
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The epidemiologic, clinical, and histologic features of Hodgkin
lymphoma are different in economically developed and developing
countries.4 Epidemiologic studies support three distinct
forms of Hodgkin lymphoma attributable to interactions of environmental
and host factors.5 The childhood form (age 14 years or
younger) is characterized by a high incidence of the mixed cellularity
histologic subtype in children living in poorer socioeconomic environments.
The young adult form (ages 15 to 34 years) shows a predominance
of the nodular sclerosing histologic subtype in Caucasian adolescents
and young adults in developed countries. An older adult form (ages
55 to 74 years) produces the characteristic bimodal distribution
of incidence of the disease in industrialized countries. In developing
countries, the early peak occurs before adolescence.
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