Lymphoma doesn’t have a single cause. It develops when white blood cells called lymphocytes acquire genetic errors that make them grow uncontrollably, but the triggers behind those errors vary widely. Some are biological, like viral infections or inherited genetic traits. Others are environmental, like long-term chemical exposure. In many cases, no clear cause is ever identified. Here’s what research has linked to increased lymphoma risk.
How Lymphoma Starts at the Genetic Level
Every lymphoma begins with a genetic malfunction inside a lymphocyte. Two of the most important genes involved are ones that control cell survival and cell growth. When pieces of chromosomes break off and reattach in the wrong place (called translocations), these genes can get switched on permanently. One common translocation locks a survival gene into overdrive, preventing damaged cells from dying the way they normally would. Another hijacks a growth gene, causing cells to multiply rapidly. When both errors occur in the same cell, the result is an especially aggressive form called “double-hit” lymphoma.
These translocations aren’t typically inherited. They arise spontaneously during a person’s lifetime, often in cells that are dividing frequently, as immune cells do when fighting infection or inflammation. That’s part of the reason chronic immune stimulation shows up repeatedly as a theme across lymphoma risk factors.
Viral and Bacterial Infections
Several infections are strongly tied to lymphoma development, and the Epstein-Barr virus (EBV) tops the list. EBV, the virus behind mononucleosis, infects most people at some point in life and then stays dormant. In certain circumstances it can push infected immune cells toward uncontrolled growth. Among people with HIV, EBV is found in 80% to 100% of Hodgkin lymphoma cases, and the virus actively produces a protein that transforms cell behavior.
HIV itself is one of the strongest known risk factors. Before modern antiretroviral therapy, people with HIV were 60 to 200 times more likely to develop aggressive B-cell lymphoma than the general population. Roughly 1% to 6% of HIV-positive individuals developed lymphoma each year. HIV drives this risk through multiple pathways: it causes chronic stimulation of immune cells, increases the amount of EBV circulating in the body, and produces a protein called Tat that directly interferes with the machinery controlling cell division.
A stomach bacterium, Helicobacter pylori, causes a specific type called MALT lymphoma in the lining of the stomach. H. pylori triggers chronic inflammation that stimulates immune cells in the stomach wall, and the bacterium injects a protein into those cells that blocks their normal self-destruct signals. The connection is so direct that treating the infection with antibiotics alone eliminates the lymphoma in 60% to 80% of early-stage cases, without any chemotherapy or radiation.
Immune System Suppression
A weakened immune system is one of the clearest risk factors for lymphoma. People who take immunosuppressive drugs after an organ transplant face dramatically elevated risk. Heart, lung, and intestinal transplant recipients have the highest rates, with some studies reporting lymphoma in up to 25% of these patients. Kidney and liver transplant recipients, who generally take lower doses of immunosuppressive drugs, develop it at rates of 1% to 5%.
The mechanism is straightforward: the immune system normally detects and destroys cells that have acquired dangerous mutations. When that surveillance is suppressed, abnormal lymphocytes can survive and proliferate. EBV reactivation plays a major role here too, since the virus is normally kept in check by a functioning immune system.
Autoimmune Diseases
Chronic autoimmune conditions significantly raise lymphoma risk, likely because the immune system stays in a state of constant activation, forcing lymphocytes to divide again and again. Each round of division is another opportunity for a genetic error.
Sjögren’s syndrome carries the highest risk among autoimmune diseases. A meta-analysis of 14 studies found that people with Sjögren’s are roughly 14 times more likely to develop lymphoma than the general population. Rheumatoid arthritis approximately doubles the risk of non-Hodgkin lymphoma and raises the risk of Hodgkin lymphoma threefold to fourfold. Lupus falls in between, with studies consistently showing a three- to sevenfold increase in lymphoma risk depending on the population studied.
Chemical and Occupational Exposures
Certain chemicals encountered in workplaces and agriculture have a proven link to lymphoma. A large meta-analysis of 51 studies found that occupational exposure to pesticides, benzene, and trichloroethylene (an industrial solvent) all increased non-Hodgkin lymphoma risk. The International Agency for Research on Cancer classifies benzene, formaldehyde, and trichloroethylene as confirmed human carcinogens, with sufficient evidence linking them to lymphoma specifically.
Among pesticides, lindane (an insecticide once widely used for lice and agricultural pest control) has the strongest evidence. Glyphosate-based herbicides, 2,4-D, and diazinon have also been associated with increased risk. Workers in aircraft manufacturing exposed to chromate compounds and mixed solvents, and agricultural workers exposed to combinations of pesticides and other chemicals, showed significantly elevated rates in individual studies. Hair dye exposure, particularly among long-term users, has appeared as a risk factor for certain subtypes as well.
Family History and Inherited Risk
Lymphoma runs in families to a modest degree. If you have a first-degree relative (parent, sibling, or child) with non-Hodgkin lymphoma, your own risk of developing it is about 1.7 times higher than average. For Hodgkin lymphoma, having an affected first-degree relative raises the risk roughly threefold. The inherited component is strongest for chronic lymphocytic leukemia, a closely related blood cancer: first-degree relatives of someone with CLL face an 8.5-fold increased risk.
These numbers reflect a combination of shared genetics and possibly shared environmental exposures. Researchers have identified multiple common gene variants that each contribute a small amount of additional risk, but no single “lymphoma gene” drives most cases. The inherited risk is real but relatively small for most subtypes, so having an affected family member doesn’t mean lymphoma is inevitable.
Body Weight and Diet
Obesity consistently appears as a risk factor across multiple large studies. A prospective study of over 900,000 U.S. adults found that obesity was associated with a 56% increase in lymphoma mortality risk for men and a 95% increase for women. Severe obesity (BMI above 35) has been linked specifically to diffuse large B-cell lymphoma, the most common aggressive subtype. Follicular lymphoma and chronic lymphocytic leukemia also show elevated rates in people with obesity.
High-calorie diets have been linked to increased risk for certain subtypes independently of body weight, though the evidence is less consistent. The biological explanation likely involves chronic low-grade inflammation that accompanies excess body fat, along with changes in hormone levels and immune function that obesity produces.
Age and Sex
Non-Hodgkin lymphoma is primarily a disease of older adults, with a median age at diagnosis of 68. Risk climbs steadily with age as genetic errors accumulate over a lifetime of cell division. Hodgkin lymphoma is different: it has a bimodal pattern, peaking in young adults (ages 15 to 30) and again after age 55.
Men develop non-Hodgkin lymphoma at notably higher rates than women. Age-adjusted incidence is about 22.4 per 100,000 for men compared with 15.6 per 100,000 for women. The reasons aren’t fully understood but likely involve a combination of hormonal differences, occupational exposure patterns, and differences in immune function.
Diagnostic Radiation
Despite reasonable concern, standard medical imaging does not appear to increase lymphoma risk. A large case-control study found no positive association between cumulative radiation dose from diagnostic procedures (X-rays, CT scans) and lymphoma. The doses involved in routine imaging are simply too low. Therapeutic radiation for a previous cancer is a different matter and has been linked to a small increase in secondary cancers, though lymphoma specifically is not among the most common ones.