Non-Hodgkin Lymphoma Facts

July 13, 2024

This page was reviewed under our medical and editorial policy by Alex Herrera, M.D., associate professor, division of lymphoma, Department of Hematology & Hematopoietic Cell Transplantation, City of Hope^® Cancer Center Duarte

Non-Hodgkin lymphoma is one of the two main types of lymphoma, and by far the more common one. Each year, roughly 80,620 Americans receive a non-Hodgkin lymphoma diagnosis, accounting for 90% of all lymphoma diagnoses, according to the National Cancer Institute. Overall, this represents about 4% of all new cancer cases in a year. This disease is sometimes referred to as non-Hodgkin’s lymphoma, NHL or simply lymphoma.

What Is Non-Hodgkin Lymphoma?

Non-Hodgkin lymphoma develops when certain white blood cells (lymphocytes) become abnormal and begin to grow and spread unchecked. Usually, the affected cells are either B lymphocytes (which make the immune system’s infection-fighting antibodies) or T lymphocytes (which destroy viruses and abnormal cells in the body). NHL may arise in the lymph nodes or elsewhere in the lymphatic system, such as the bone marrow, spleen or other tissue.

Non-Hodgkin lymphoma is complex and has many diverse subtypes — classified by the type of lymphocyte affected and other factors (such as how the cancer looks under the microscope). All of those non-Hodgkin lymphoma types together are grouped into two broad categories: indolent and aggressive.

• Indolent NHL types tend to progress slowly, may cause few signs or symptoms, and may not need treatment right away.
• Aggressive forms, in contrast, grow and spread quickly, with sometimes severe symptoms.

The specific symptoms of NHL vary, partly depending on where the cancer occurs in the body. Non-Hodgkin lymphoma symptoms may include:

• Enlarged lymph nodes in the neck, armpit or groin
• Unexplained fever
• Drenching night sweats
• Fatigue
• Appetite loss and/or weight loss
• Pain, swelling or a feeling of fullness in the abdomen
• Chest pain, coughing or trouble breathing
• Frequent infections
• Easy bruising or bleeding

What Causes Non-Hodgkin Lymphoma?

The root causes of non-Hodgkin lymphoma are not fully understood, in part because the disease encompasses so many subtypes. However, NHL does involve abnormal changes in genes that affect lymphocytes. Those genetic changes are largely acquired during life, and not inherited at birth.

Research has uncovered some specific genetic changes that may lead to certain forms of NHL. One example is follicular lymphoma, the most common type of indolent lymphoma among Americans. In that disease, cells often have a DNA flaw that “turns on” the BCL-2 oncogene. When that gene is abnormally active, cells don’t die when they’re supposed to, which may lead to lymphoma.

Non-Hodgkin Lymphoma Risk Factors

Risk factors are characteristics linked to a higher-than-average chance for developing a disease; they are not necessarily a cause of the disease. Research has identified numerous risk factors for NHL, though some are linked only to certain subtypes.

Older age: In general, the risk of NHL goes up with age. The most common subtypes most often affect people in their 60s and 70s, though some forms are more common in younger people.

Being male: Most forms of non-Hodgkin lymphoma are more common in men than women, though the reverse is true for certain subtypes. The reasons for those differences are unknown.

Family history: Having a parent, sibling or child with a history of NHL increases a person’s risk to slightly higher than average. This means overall odds of developing the cancer are still low.

Weakened immune system: People with HIV or other immune deficiencies have a higher-than-average risk of NHL, as do people who are on immune-suppressing drugs after an organ transplant.

Autoimmune diseases: Certain autoimmune conditions — such as rheumatoid arthritis, lupus and Sjögren’s syndrome — are tied to an increased NHL risk. These conditions involve immune system overactivity, which might cause lymphocytes to grow and divide faster than normal in some people.

Radiation exposure: People treated with radiation therapy for other cancers have a heightened risk for developing NHL later in life — particularly if they also received chemotherapy. This may also include exposure to radiation from atomic bombs and nuclear reactor accidents.

Chemicals: Exposure to certain chemicals, such as benzene (a widely used chemical found in sunscreens and other body products and in the manufacturing of plastics and products) and some pesticides and weed killers, have been linked to NHL risk.

Chronic infections: Long-term infection with certain viruses and bacteria — such as Epstein-Barr virus, Helicobacter pylori (which may cause stomach ulcers) and hepatitis C — has been tied to some NHL subtypes. It is thought that this may be due to direct damage to lymphocytes or to immune system overstimulation. However, the relationship between infections and NHL is complicated since some of the implicated infections are very common.

Keep in mind that NHL is a relatively rare disease, so even when people have some of these risk factors, the likelihood of developing the cancer may still be low. According to the American Cancer Society, the average lifetime risk of NHL for men is one in 42. For women, it is one in 52.