What Causes Lymphoma?

Learn about the main factors that can increase the risk of lymphoma developing. 

Lymphoma starts with changes in white blood cells

Lymphoma begins in lymphocytes, a type of white blood cell that helps fight infection. Sometimes, these cells change and start to grow too fast.

This happens because of changes in DNA. DNA controls how cells grow and divide. Over time, these changes can build up and affect how the cells behave.

This process is called clonal proliferation, which means one abnormal cell makes many copies of itself. Some changes can also keep cells from dying when they should.

There is usually no single cause. Instead, lymphoma often develops from several factors working together over time. 

A weakened immune system increases risk

The immune system protects the body from infections and abnormal cells. When it is weak, the risk of lymphoma is higher. This can happen with:

• Autoimmune conditions like rheumatoid arthritis or lupus
• HIV infection
• Medicines used after an organ transplant

When the immune system is not working well, it may not remove abnormal cells as it should. 

Some infections are linked to lymphoma

Certain viruses can increase the risk of lymphoma by affecting how immune cells grow. These include:

• Epstein-Barr virus (EBV)
• Human T-cell lymphotropic virus type 1 (HTLV-1)
• Hepatitis C virus
• Kaposi sarcoma-associated herpesvirus

EBV can affect different types of immune cells, including B cells and T cells. Most people with these infections do not develop lymphoma, but they can raise the risk.

Environmental and lifestyle factors

Some exposures and habits may increase risk over time, such as:

• Pesticides or herbicides
• Diets high in fat and processed meats
• Smoking

These factors may affect the body in different ways. Chemicals in pesticides and herbicides can damage DNA over time. This may lead to changes in how cells grow. Diets high in fat and processed foods may increase inflammation. Inflammation is the body’s response to stress or injury, and long-term inflammation can affect how cells behave. Smoking can weaken the immune system and expose the body to harmful substances that may damage cells.

These factors do not directly cause lymphoma, but they may play a role over time. 

Age and personal risk factors

Some people have a higher risk based on personal traits. These include:

• Older age
• Being male
• Being Caucasian

These factors cannot be changed, but they help explain patterns in lymphoma.

Family history and inherited risk

Family history can affect the risk of lymphoma, but it is not common. Research shows that people with a first-degree relative, such as a parent, sibling, or child, have a higher risk. The risk is about:

• 1.7 times higher for non-Hodgkin lymphoma
• 3.1 times higher for Hodgkin lymphoma
• 8.5 times higher for chronic lymphocytic leukemia (CLL) 

The risk is usually highest for the same type of lymphoma seen in the family. This suggests that some inherited genetic factors may be specific to each type. 

Even with this increase, the overall chance of developing lymphoma is still low. For example, a person’s lifetime risk may rise from about 2% to around 3% to 4%.

Researchers believe this risk is linked to many small genetic changes, not one single gene. These small changes can affect how the immune system works and how cells grow.

Why lymphoma causes are not always clear

Lymphoma often develops from a mix of factors. These can include immune system changes, infections, genetic changes, and environmental exposures. Most people do not have one clear cause. 

Because of this, there is no sure way to prevent lymphoma. Still, learning about these risk factors can help you better understand your diagnosis and talk with your care team.

There are steps you can take to reduce the risk of developing secondary cancers. 

Sources: 

• Lymphoma | Am I at Risk?
• NIH | Lymphoma Etiology
• Epidemiology and Etiology of Leukemia and Lymphoma
• Etiology of non-Hodgkin lymphoma: A review from epidemiologic studies
• Viral Causes of Lymphoma: The History of Epstein-Barr Virus and Human T-Lymphotropic Virus 1
• Cancer Prevention Overview
• Familial predisposition and genetic risk factors for lymphoma
• Pathogenesis and Pathology of Pediatric Lymphoma
• Epidemiologic overview of malignant lymphoma