Lymphoma develops when cells in your lymph system start to grow abnormally, but doctors do not yet fully understand why this happens in some people and not others

Lymphoma begins when lymphocytes—a type of white blood cell that normally fights infection—become cancerous and multiply out of control. These abnormal cells collect in lymph nodes, the spleen, bone marrow, or other organs. The exact reason a person's lymphocytes turn cancerous remains unknown. Researchers have identified certain risk factors and conditions that make lymphoma more likely, but having a risk factor does not mean you will develop the disease.

There are two main types: Hodgkin lymphoma and non-Hodgkin lymphoma. Non-Hodgkin lymphoma is far more common, accounting for about 90 percent of lymphoma cases. The causes and risk factors differ somewhat between the two types, and within non-Hodgkin lymphoma there are many subtypes, each with its own pattern of development.

Key Takeaways

  • Lymphoma occurs when lymphocytes become cancerous and multiply, but no single cause has been identified—it appears to result from a combination of genetic and environmental factors.
  • Risk factors include a weakened immune system, certain infections (such as Epstein-Barr virus or HIV), autoimmune diseases, and a family history of lymphoma.
  • Age matters: Hodgkin lymphoma peaks in the 20s and again after age 55, while non-Hodgkin lymphoma risk increases steadily with age.
  • Exposure to certain chemicals, pesticides, or radiation may increase risk, though the connection is not proven for most people who develop lymphoma.
  • Most people with lymphoma have no known risk factors, meaning the disease can occur in anyone regardless of lifestyle or medical history.

Immune system weakness and infection as contributing factors

A weakened or suppressed immune system significantly raises the risk of developing lymphoma. People with HIV, those who have had an organ transplant and take immunosuppressive drugs, and individuals with inherited immune disorders all face higher rates of lymphoma. The immune system normally prevents abnormal cells from multiplying; when that surveillance fails, cancerous cells can take hold.

Certain infections also appear connected to lymphoma development. Epstein-Barr virus (EBV), the virus that causes mononucleosis, has been linked to some types of non-Hodgkin lymphoma, particularly in people with weakened immunity. Hepatitis C virus and human T-cell leukemia virus (HTLV-1) are associated with specific lymphoma subtypes. Helicobacter pylori, a bacterium that causes stomach ulcers, can trigger a rare type of lymphoma in the stomach lining. Having one of these infections does not mean you will develop lymphoma, but the connection is well-established.

Autoimmune disease and chronic inflammation

People with autoimmune diseases—conditions where the immune system attacks the body's own cells—have a higher risk of lymphoma. Rheumatoid arthritis, lupus, Sjögren's syndrome, and celiac disease all carry increased risk. The constant inflammation and immune system activation that characterize these diseases may create an environment where lymphocytes are more likely to become cancerous over time.

The risk is real but still relatively small. Most people with autoimmune disease never develop lymphoma. The connection appears strongest in people whose autoimmune disease has been active for many years or who take certain medications to suppress their immune response.

Age and family history

Age is one of the strongest predictors of lymphoma risk. Non-Hodgkin lymphoma becomes increasingly common as people age, with most diagnoses occurring in people over 60. Hodgkin lymphoma follows a different pattern: it peaks in the 20s, then again after age 55. Young adults and older adults face the highest risk for Hodgkin lymphoma, while middle-aged and older people face the highest risk for non-Hodgkin lymphoma.

Family history matters, though lymphoma is not typically inherited in a straightforward way. If a close relative—parent, sibling, or child—has had lymphoma, your risk is higher than average. However, most people with a family history of lymphoma never develop it themselves. Genetic predisposition appears to make certain people's cells more vulnerable, but other factors must also be present for lymphoma to actually develop.

Chemical and environmental exposures

Exposure to certain chemicals and pesticides has been studied as a possible risk factor. People who work in agriculture, pesticide manufacturing, or certain industrial settings show slightly higher lymphoma rates in some studies. Exposure to benzene, a chemical used in manufacturing, has been linked to lymphoma in occupational settings. However, the connection is not strong enough to say that exposure will cause lymphoma in any particular person.

Radiation exposure, particularly at high doses, increases lymphoma risk. People who survived atomic bomb radiation or received radiation therapy for other cancers face elevated risk. Occupational radiation exposure in medical or nuclear settings carries some risk, though modern safety standards have greatly reduced this. Again, exposure does not may provide development of the disease.

Genetic changes that occur after birth

Lymphoma always involves genetic changes—mutations in the DNA of lymphocytes—but these changes almost never run in families. Instead, they happen randomly in individual cells during a person's lifetime. A single mutation is not enough; typically several mutations must accumulate in the same cell before it becomes cancerous. This is why lymphoma usually develops later in life, when cells have had more time to accumulate damage.

Researchers have identified specific genetic changes associated with different lymphoma subtypes. Some lymphomas carry a translocation, where a piece of one chromosome attaches to another, disrupting normal cell growth controls. Others have mutations in genes that regulate cell death or immune response. Understanding these changes helps doctors classify lymphomas and choose treatment, but it does not explain why those mutations occurred in the first place.

Why most people with lymphoma have no clear cause

The majority of people diagnosed with lymphoma have no obvious risk factors. They may have no family history, no immune system problems, no chemical exposure, and no known infections. This does not mean the disease appeared for no reason—it means the combination of factors that led to it remains unknown. Lymphoma likely results from a mix of small genetic vulnerabilities, random mutations, and environmental influences that vary from person to person.

This unpredictability is why lymphoma cannot be prevented through lifestyle changes alone. While maintaining overall health is always worthwhile, there is no proven way to prevent lymphoma in someone without known risk factors. The disease can occur in people who exercise regularly, eat well, avoid smoking, and have no family history.

Frequently Asked Questions

Can you catch lymphoma from someone else?

No. Lymphoma is not contagious. While certain infections like Epstein-Barr virus can increase risk, the virus itself does not cause lymphoma in most people who have it. You cannot catch lymphoma from a family member, friend, or coworker who has the disease.

Does stress cause lymphoma?

There is no scientific evidence that stress causes lymphoma. While chronic stress can affect immune function, no study has proven that stress leads to lymphoma development. Many people experience significant stress without developing lymphoma, and many people with lymphoma had no unusual stress before diagnosis.

If my parent had lymphoma, will I definitely get it?

No. Having a parent with lymphoma increases your risk above the general population, but most children of lymphoma patients never develop the disease. Your risk depends on many factors beyond family history, including your own immune system, exposures, and random genetic events.

Does diet or lifestyle prevent lymphoma?

There is no proven diet or lifestyle change that prevents lymphoma. While healthy habits support overall health, they have not been shown to reduce lymphoma risk specifically. People who develop lymphoma often had no modifiable risk factors.

What should I do if I have multiple risk factors?

Having multiple risk factors means your risk is higher than average, but it does not mean you will develop lymphoma. Talk with your doctor about your specific situation. Some people benefit from more frequent check-ups or awareness of early symptoms, though routine screening for lymphoma in asymptomatic people is not standard practice.