What is lymphoma? 

Lymphoma is a blood cancer that affects the lymphocytes, which are part of the white blood cells, and are crucial to the immune system. ‘Lymph’ refers to the lymphatic system, sometimes described as the body’s drainage system, because it helps maintain fluid levels by collecting waste that escapes from blood vessels. Lymphocytes, like other immune cells, help protect the body from infections. They are divided into two main types: T lymphocytes (T-cells) and B lymphocytes (B-cells).¹

Cancers are typically caused by cells that divide without control. In lymphoma, lymphocytes grow and accumulate in the lymphatic system, forming tumours throughout the body.

What are the different types of lymphoma? 

Lymphoma is divided into two main types: Hodgkin Lymphoma (HL) and Non-Hodgkin Lymphoma (NHL). What generally separates the two is the presence of a distinctive cell type known as Reed-Sternberg cells. Reed-Sternberg cells are relatively easy to identify because of their large size and the presence of more than one nucleus. The presence of these cells indicates the diagnosis is Hodgkin Lymphoma, while their absence indicates NHL. Hodgkin Lymphoma is less common than NHL and usually more treatable. NHL is more common and can affect different immune cells, leading to several subtypes of NHL.² 

Other forms of lymphoma discussed in this article include MALT lymphoma, Adult T-cell leukaemia/lymphoma (ATL) and post-transplant lymphoproliferative disorder (PTLD).^3,4,5 Each type of lymphoma has unique features, but all involve abnormal, uncontrollable growth of lymphocytes that disrupts normal immune system function.

Why understanding risk factors for lymphoma matters 

The human body can be unpredictable, just like many diseases. However, certain factors, such as health conditions, behaviours, or environmental exposures, may increase the likelihood of developing a disease, as shown by research and patient cases. These are known as risk factors for a specific disease, and recognising them may help with early detection and potentially reduce the chances of the disease developing. It is also important to note that many people with risk factors for lymphoma may never develop the condition, while others with no known risk factors may still be diagnosed.

Non-modifiable risk factors (things you cannot control)

Age

Generally, the risk of lymphoma increases with age, especially in cases of NHL. The most diagnosed age group for NHL is people over 60. Unlike NHL, Hodgkin lymphoma is more common in two age groups: younger adults aged 15-35, and older adults over 55.⁶ The exact reason why people over 50 face a higher risk of developing lymphoma is not fully understood. However, it is thought that mutations are more likely to occur with age, making older individuals more vulnerable to abnormal lymphocyte growth.

Gender

Gender appears to influence the likelihood of developing most lymphoma subtypes, with people assigned male at birth having a higher risk of diagnosis. More specifically, NHL is more common in people assigned male at birth.⁷

Family history

There may be a genetic influence when multiple family members or close relatives are diagnosed with lymphoma. Although the link between family history and cancer risk is not fully understood, it may involve inherited genes that are more prone to mutations affecting lymphocyte function. Inherited immune disorders that weaken the immune system may also increase lymphoma risk, as they make it harder to detect and control overreactive lymphocytes.⁶

Autoimmune conditions

Conditions such as rheumatoid arthritis (RA), lupus, Sjögren’s syndrome, and coeliac disease are linked to a higher risk of lymphoma, particularly NHL. In these conditions, the immune system mistakenly attacks the body, causing an overactive immune response that can lead to lymphocyte production. In addition, treatments for autoimmune conditions can further weaken the immune system, which may increase the risk of lymphoma.⁶

Modifiable risk factors (things you can control)

Compromised immune system

Conditions that severely weaken the immune system, such as HIV/AIDS, raise the likelihood of developing lymphoma. This is because the immune system cannot fight the spread of abnormal lymphocytes as effectively as in a healthy individual.⁸

People who have received an organ transplant are also at a higher risk of developing lymphoma. After transplantation, immunosuppressive drugs are given to prevent the body from rejecting the new organ. However, this weakens the immune system’s ability to monitor abnormal cell division, allowing lymphocytes to divide uncontrollably. The type of lymphoma that can develop in these cases is called post-transplant lymphoproliferative disorder (PTLD), which is often linked to Epstein-Barr virus (EBV) – this will be discussed further in the ‘Infections’ section.⁹

Infections

Several infections affect the human body using distinct mechanisms, which can disrupt the normal function of the immune system and promote the growth of cancer. The following infections have been associated with a higher probability of developing lymphoma:

• Epstein-Barr virus (EBV) is a common virus, known for causing mononucleosis, or ‘mono’. It infects B lymphocytes (B-cells) of the immune system, and can become dormant (inactive) after infection, remaining in the body for life. In immunosuppressed individuals (such as those with HIV, transplant recipients, and people with autoimmune conditions), EBV can reactivate and lead to lymphoma¹⁰
• Human T-cell Leukaemia Virus type 1 (HTLV-1) infects T lymphocytes (T-cells), causing them to divide uncontrollably, which may increase the risk of lymphoma, especially adult T-cell leukaemia/lymphoma (ATL)¹¹
• Helicobacter pylori is a bacterium found in the stomach, responsible for chronic inflammation and stomach ulcers. This long-term irritation is managed by the immune system, but it can lead to immune dysregulation, including overreaction of immune cells. This may result in a rare case of lymphoma called mucosa-associated lymphoid tissue lymphoma (MALT)¹²

Chemical and radiation exposure

Exposure to pesticides, herbicides (such as Agent Orange), and benzene –either through work or the environment– can increase the risk of DNA mutations, promoting uncontrolled cell growth.¹³

Radiation from environmental sources (such as nuclear facility work, nuclear bomb-affected areas) and certain medical treatments (like radiation therapy) can also create DNA mutations, raising the risk of lymphoma and other cancer types.¹⁴

Lifestyle choices

Certain habits and life choices may increase the risk of developing lymphoma. Smoking and using tobacco products increase the risk of lymphoma, as tobacco is a known carcinogen that can affect lymphocytes and promote lymphoma development. Obesity may also raise the risk of lymphoma, as it can cause chronic inflammation, leading to immune system disruption.¹⁵

FAQs

Can lymphoma be prevented?

Lymphoma, like all cancers, cannot be fully prevented. However, avoiding controllable risk factors, such as chemicals, radiation, unsafe sex (which may lead to HIV) and infections linked to lymphoma, may reduce the risk. Maintaining a healthy lifestyle, managing infections and autoimmune conditions, and monitoring for any suspected signs of lymphoma are the best approaches to avoid its development and ensure early detection.

What are the early symptoms of lymphoma?

The most common symptoms of lymphoma include swelling of the lymph nodes, especially in the neck, armpits and groin. Other symptoms, such as fatigue, fever, and unexplained weight loss, may also indicate lymphoma. If you notice symptoms and suspect exposure to the risk factors discussed, it is important to consult a healthcare provider. Most lymphomas have high survival rates when detected early, and catching the disease before it spreads greatly improves recovery chances.

How is lymphoma diagnosed?

Lymphoma is diagnosed through a combination of blood tests, biopsies of inflamed lymph nodes, and scans (such as PET or CT scans). A bone marrow test may also be performed to confirm the diagnosis and check how far the disease has spread.

Summary

Lymphoma is a complex condition with various causes, some of which we can control and some we cannot. Research and patient cases show that certain risk factors, such as family history, autoimmune disorders, infections, and environmental exposures (certain chemicals and radiation), increase the risk of lymphoma. Nevertheless, the exact mechanism behind it is still not fully understood. Avoiding certain triggers and understanding how a person may be predisposed to lymphoma is crucial for early detection and improving the chances of successful treatment.