Epidemiology of Hodgkin and Non-Hodgkin Lymphoma
Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL) represent distinct epidemiological entities with different incidence patterns, risk factors, and demographic distributions. 1
Hodgkin Lymphoma Epidemiology
- The crude incidence of HL in the European Union is 2.3 cases per 100,000 population per year, with a mortality rate of 0.4 cases per 100,000 per year 1
- HL demonstrates a bimodal age distribution with peaks in young adults aged 20-40 years and in individuals aged 55 years and older 1, 2
- Slightly more men than women are diagnosed with HL 1
- Histologically, HL is divided into two main types:
- The incidence of nodular sclerosis subtype has increased progressively since 1973, particularly in young adults, with a marked increase in young adult women 2
- Mixed cellularity subtype (23.4% of HL) has remained stable over time, though with increased incidence in Black males over 40 years 2
- Lymphocyte predominance subtype (6% of HL) has remained stable over time 2
- Lymphocyte depletion subtype (3.8% of HL) occurs predominantly in the elderly 2
Non-Hodgkin Lymphoma Epidemiology
- NHL constitutes a heterogeneous group of lymphoproliferative malignancies with varying patterns of behavior and responses to treatment 1
- The crude incidence of DLBCL (the most common NHL subtype) in Europe is 3.8 cases per 100,000 per year 1
- Recent epidemiologic data suggest a worldwide increase in NHL incidence (approximately 30% in 5 years prior to 2010) 1
- Most NHL cases (approximately 90%) are of B-cell origin 3
- The two most common NHL subtypes are:
- NHL occurs frequently in the elderly, with a median age greater than 60 years 4
- Regional variations in NHL subtypes exist:
- Lower incidence of follicular lymphoma and chronic lymphocytic leukemia in Asian countries compared to Europe and North America 1
- Higher incidence of T-cell lymphomas in Asian countries compared to Europe and North America 1
- Higher incidence of Epstein-Barr virus-associated lymphomas in some Middle East countries 1
- HTLV-1-associated adult T-cell leukemia/lymphoma (ATL) is endemic in some Middle East regions 1
Risk Factors
- Family history of lymphoma 1
- Autoimmune diseases 1
- HIV infection 1, 2
- Hepatitis C virus (HCV) seropositivity 1
- High body mass as a young adult 1
- Certain occupational exposures 1
- Environmental factors, including increased pesticide use 1
- Infectious diseases 1
Prognostic Factors
- Age is a significant prognostic factor in NHL, with patients under 60 years having better survival outcomes than those over 60 years 4
- Smoking, alcohol consumption, and obesity before diagnosis are associated with poorer overall and lymphoma-specific survival in NHL patients 1
- Molecular and genetic markers are increasingly being identified as important prognostic indicators 3
- Tumor microenvironment factors (immune and stromal infiltration) are emerging as prognostic factors 1
Relationship Between HL and NHL
- Some cases show both HL and NHL present in the same anatomic site (composite lymphomas) or in separate sites (simultaneous or sequential HL and NHL), occurring more frequently than would be expected by chance 5
- The most common form of composite lymphoma is coexistent NLPHL with large-cell lymphoma of B-cell immunophenotype 5
- Late occurrence of aggressive B-cell NHL in patients successfully treated for HL may be related to persistent immunodeficiency in these patients 5
Recent Advances in Classification and Staging
- The Lugano Classification has modernized recommendations for evaluation, staging, and response assessment of both HL and NHL 1
- FDG-PET/CT has been formally incorporated into standard staging for FDG-avid lymphomas 1
- Bone marrow biopsy is no longer indicated for routine staging of HL and most diffuse large B-cell lymphomas 1