Hodgkin lymphoma (HL) was recognized in the first half of the nineteenth century by Thomas Hodgkin and Samuel Wilks (1). HL usually arises in lymph nodes, preferentially in the cervical area, and the majority of HLs manifest clinically in young adults in their third and fourth decades of life. The incidence of HL is 3.0 per 100,000 person-year in the United States; it is higher in the Western countries than Asian countries (2,3). Biological and clinical studies have shown that HLs are comprised of two disease entities: nodular lymphocyte-predominant HL (NLPHL) and classical HL (cHL) (1). The two entities differ in their clinical features and behavior. Within cHL, four subtypes have been described: nodular sclerosis, mixed cellularity, lymphocyte-rich, and lymphocyte-depleted. These four subtypes differ in their clinical features, growth pattern, presence of fibrosis, and frequency of Epstein-Barr virus infection but share the immunophenotype of tumor cells.
The management of HL continues to evolve. Before the widespread use of modern polychemotherapy, large-field radiation therapy was able to cure cHL patients. However, reliance on radiation alone required extensive radiation portals to treat nearly the entire lymphatic system with radiation doses up to 44 Gy. With long-term follow-up, many patients developed heart toxicity and second malignancies. Therefore, efforts have been made to reduce the long-term toxicities of treatment for HL while maintaining excellent cure rates. With modern chemotherapy, multiple randomized studies have shown that radiation portals can be safely reduced from extended-field radiation to involved-field radiation and, now, even smaller fields of radiation, including involved-node radiation.
Currently, the treatment of cHL is stratified by risk groups—early-stage favorable, early-stage unfavorable, and advanced-stage disease—according to the clinical stage and the presence or absence of adverse clinical features. In this chapter, we will review advances in the management of HL, including recent publications about strategies of management of the rarer diagnosis of NLPHL.
TYPES OF HODGKIN LYMPHOMA
Over the past decade, investigators have made significant progress in the diagnosis, classification, staging, prognosis, and treatment of HL. In past years, the true lineage of the neoplastic cells in HL was unknown; hence, the term Hodgkin disease was used. It is now recognized that almost all cases of HL are of B-cell lineage; hence, the name changed to Hodgkin lymphoma.
The classification of HL has remained relatively stable over the past 40 years, and the World Health Organization (WHO) classification of lymphoid neoplasms was updated in 2008 (1) (Table 10-1). The current WHO classification recognizes that NLPHL is distinct from the other types that can be grouped together under the rubric of cHL (1).
Table 10-1World Health Organization Classification of Hodgkin Lymphoma