Lymphoma is a form of cancer that originates in lymphocytes, which are a type of white blood cell belonging to the body’s immune system. These abnormal cells begin to multiply uncontrollably, often accumulating in lymph nodes, but they can also affect other parts of the body. The likelihood and the specific type of lymphoma a person might encounter are frequently tied to their age.
The Bimodal Pattern of Hodgkin Lymphoma
Hodgkin lymphoma (HL) exhibits a distinct “bimodal” age distribution, meaning its incidence rates show two separate peaks. The first peak typically occurs in young adulthood, commonly affecting individuals between the ages of 15 and 40 years. This peak often includes those in their early twenties. The nodular sclerosis subtype, a common form of HL, has shown a progressive increase in incidence in this younger age group.
A second peak in HL incidence is observed later in life, usually in older adulthood, affecting individuals aged 55 years and older. While HL is generally rare in children, its presence in adolescents and young adults aligns with this initial peak. This two-peaked pattern is a distinguishing characteristic of Hodgkin lymphoma.
Increasing Risk of Non-Hodgkin Lymphoma With Age
Non-Hodgkin lymphoma (NHL) represents a broader category of lymphomas, and its age distribution differs significantly from Hodgkin lymphoma. The risk of developing most types of NHL steadily increases as individuals age.
The majority of NHL cases are diagnosed in older adults, with more than half of all diagnoses occurring in people aged 65 or older. Incidence rates are highest in the 80 to 84 age group, with nearly four in ten new cases diagnosed in individuals aged 75 and over. While the overall trend shows a clear increase with advancing age, some aggressive subtypes of NHL can still affect younger individuals.
Lymphoma in Children and Young Adults
Although lymphoma is less common in children compared to adults, it is recognized as one of the more frequent cancers among pediatric and young adult populations. Lymphoma accounts for approximately one in five cancers in young people aged 15 to 24 years. Hodgkin lymphoma is notably common in adolescents and young adults, consistent with its first incidence peak.
Conversely, non-Hodgkin lymphoma in children and teens often presents as fast-growing, aggressive subtypes that differ from those commonly seen in adults. Examples include Burkitt lymphoma, which accounts for about 30% of childhood NHL and is highly aggressive, and lymphoblastic lymphoma, making up about 20% of NHL in children. Diffuse large B-cell lymphoma (DLBCL) is another type, more frequently seen in older children and teenagers, accounting for 15% to 20% of childhood NHL.
Biological Reasons for Age-Related Differences
The varying age patterns of lymphoma are underpinned by several biological mechanisms that change with aging. One significant factor is immunosenescence, which refers to the natural decline in the immune system’s function as a person ages. This weakening immune response makes the body less effective at identifying and eliminating abnormal cells, including those that could become cancerous. Specifically, the thymus, where T-cells mature, involutes with age, leading to a decreased production of new T-cells and a less diverse T-cell repertoire, thereby impairing the body’s ability to fight off potential malignancies.
Another contributing factor is the accumulation of cellular DNA damage over time, which can result from biological processes or environmental exposures. Over decades, cells are exposed to various environmental factors and undergo numerous replication cycles, increasing the statistical probability of DNA damage and errors. These accumulated genetic changes can lead to the activation of cancer-promoting genes or the inactivation of tumor-suppressing genes within lymphocytes, ultimately increasing the risk of lymphoma development in older individuals.