Lymphoma develops when white blood cells called lymphocytes acquire DNA mutations that cause them to multiply uncontrollably instead of dying on schedule. There is no single main cause. Instead, lymphoma arises from a combination of factors: errors during normal immune cell development, viral infections, chronic immune system activation, immunosuppression, and environmental exposures. In most cases, the gene changes responsible are acquired during a person’s lifetime rather than inherited.
With roughly 79,000 new cases of non-Hodgkin lymphoma alone expected in the U.S. each year and a median age at diagnosis of 68, understanding what drives these mutations matters for a wide range of people.
How Normal Immune Cells Become Cancerous
Your immune system constantly builds new lymphocytes, and each one undergoes a complex process of genetic reshuffling to produce unique receptors capable of recognizing specific threats. Proteins in the cell initiate targeted DNA breaks so gene segments can recombine into new configurations. This is a normal, essential process, but it’s also inherently risky. During this reshuffling, pieces of chromosomes can accidentally swap places or land next to genes they shouldn’t activate.
These misplaced chromosome segments can switch on genes that promote cell growth or block the signals that tell a cell to stop dividing. A second wave of genetic changes happens after B cells encounter an actual infection and begin refining their attack in the lymph nodes. During this refinement, further mutations and chromosome swaps can disrupt the balance between cell growth and cell death, effectively making a B cell immortal. That immortal, endlessly dividing cell is the seed of lymphoma.
Both Hodgkin and non-Hodgkin lymphoma typically arise from B cells, though non-Hodgkin lymphoma can also develop from T cells or natural killer cells. The distinction matters because the cell of origin influences how the cancer behaves and responds to treatment.
Viral Infections That Drive Lymphoma
Certain viruses don’t just coincide with lymphoma; they actively rewire the cells they infect. The Epstein-Barr virus (EBV), which causes mono and infects the vast majority of adults worldwide, is the most well-studied example. EBV is linked to Burkitt lymphoma, Hodgkin lymphoma, diffuse large B-cell lymphoma, and several rarer subtypes.
EBV transforms B cells through multiple mechanisms working simultaneously. One viral protein mimics a normal growth signal, tricking the cell into behaving as though it’s been activated by the immune system when it hasn’t. Another blocks the self-destruct pathway that would normally eliminate a damaged cell. The virus also silences tumor suppressor genes by chemically modifying their DNA, essentially turning off the cell’s built-in brakes. Together, these changes push infected B cells toward uncontrolled growth.
The risk is especially pronounced in people with weakened immune systems, such as those living with HIV or those on immunosuppressive drugs after an organ transplant. In healthy people, the immune system keeps EBV-infected cells in check. When that surveillance fails, EBV-driven lymphoma becomes far more likely.
Bacterial Infection and Stomach Lymphoma
One of the clearest cause-and-effect relationships in all of cancer biology involves the bacterium H. pylori and a type of lymphoma that forms in the stomach lining. Chronic H. pylori infection triggers persistent inflammation, and the immune tissue that accumulates in response provides a breeding ground for cancerous B cells. Over time, the ongoing inflammation generates reactive oxygen species that damage DNA, while the immune environment around the infection supports the survival and expansion of a malignant B-cell clone.
In the early stages, the cancerous cells are still dependent on the inflammatory signals driven by the infection. This means that eliminating H. pylori with antibiotics can cause the lymphoma to regress completely, making it one of the rare cancers effectively treated by curing an infection.
Autoimmune Diseases and Chronic Inflammation
Conditions that keep the immune system in a state of chronic activation significantly raise lymphoma risk. A large nationwide study tracking patients over several decades found elevated rates of non-Hodgkin lymphoma across more than 20 autoimmune diseases. The strongest associations were dramatic: people with autoimmune hemolytic anemia (where the body destroys its own red blood cells) had a risk 27 times higher than the general population. Immune thrombocytopenic purpura carried a 7.5-fold increase.
Sjögren’s syndrome, an autoimmune condition affecting moisture-producing glands, increased risk nearly fivefold. Celiac disease and lupus each roughly quadrupled it. Even more common conditions showed meaningful increases: rheumatoid arthritis doubled the risk, and psoriasis raised it by about 40%.
The underlying logic is consistent across all of these diseases. When lymphocytes are constantly stimulated to divide and fight, the odds of a cancer-causing mutation slipping through increase with every round of cell division. The same genetic reshuffling processes that make normal immune responses possible become a liability when they never shut off.
Immunosuppression After Organ Transplant
People who receive organ transplants take medications that deliberately suppress the immune system to prevent rejection. This creates a vulnerability. During the first year after a kidney transplant, the risk of developing lymphoma is about 20 times higher than in the general population. For heart transplant recipients, that number jumps to 120-fold. Heart-lung transplant recipients face the highest relative risk of all, nearly 240 times the normal rate.
The type and intensity of immunosuppressive treatment matters. Certain powerful anti-rejection drugs used during induction therapy (the aggressive initial phase of immunosuppression) further increase the risk, particularly when given at high cumulative doses. Over a 10-year period, kidney transplant recipients overall carry a lymphoma risk roughly 12 times higher than a matched group of people who never received a transplant.
Most post-transplant lymphomas are driven by EBV, which underscores how central immune surveillance is to keeping viral-driven cell growth in check. When the immune system is intentionally weakened, EBV-infected B cells that would normally be eliminated can proliferate freely.
Environmental and Chemical Exposures
Occupational exposure to certain pesticides is associated with increased non-Hodgkin lymphoma risk. A systematic review and meta-analysis found consistent positive associations for several chemical classes: phenoxy herbicides, carbamate insecticides, organophosphorus insecticides, and the organochlorine insecticide lindane. The herbicide glyphosate, the active ingredient in widely used weed killers, showed a positive association specifically with B-cell lymphoma.
Diffuse large B-cell lymphoma, one of the most common aggressive subtypes, was positively associated with phenoxy herbicide exposure. These findings are most relevant to agricultural workers and others with prolonged occupational contact, not casual home garden use. Benzene exposure, which occurs in certain industrial settings, is another recognized risk factor.
Genetics and Family History
Having a close relative with lymphoma does increase your risk, but inherited genetics play a relatively small role overall. Most lymphoma develops from gene changes acquired during a person’s lifetime, not from mutations passed down from a parent. The American Cancer Society notes that while family history matters, most people diagnosed with lymphoma have no strong family history of the disease.
What is inherited, in many cases, are subtler variations in immune system genes that influence how efficiently your body repairs DNA damage, controls inflammation, or suppresses viral infections. These genetic differences don’t cause lymphoma directly but can make a person more vulnerable to the other risk factors described above. The interplay between inherited susceptibility and lifetime exposures explains why two people with the same infection or autoimmune disease can have very different outcomes.
Why There Is No Single Cause
Lymphoma is better understood as a convergence of risk factors than the result of any one trigger. The underlying event is always the same: lymphocytes acquire mutations that allow them to grow without restraint. But what causes those mutations varies widely, from the inherent risk of normal immune cell development, to viral hijacking of cellular machinery, to decades of chronic inflammation, to chemical exposures that damage DNA directly.
For most people diagnosed with lymphoma, no single identifiable cause can be pinpointed. The disease typically results from an unlucky accumulation of genetic errors over time, sometimes accelerated by one or more of the risk factors above. This is why lymphoma becomes more common with age, as a longer life simply means more opportunities for these errors to accumulate and escape the body’s repair mechanisms.