Lymphoma is a cancer of the lymphatic system, specifically a cancer that starts in white blood cells called lymphocytes. These are the immune cells your body uses to fight infections. When lymphocytes develop DNA changes that cause them to multiply uncontrollably and resist their normal programmed death, they accumulate in the lymph nodes and other tissues, forming tumors that crowd out healthy cells.
How Lymphoma Develops
Your lymphatic system is a network of vessels, nodes, and organs (including your spleen and bone marrow) that produces and circulates lymphocytes throughout your body. Lymph nodes are small, bean-shaped structures clustered in your neck, armpits, groin, chest, and abdomen. In lymphoma, cancerous lymphocytes build up in these nodes and can also spread to the blood, bone marrow, spleen, and other organs. As the abnormal cells accumulate, they form tumors that limit the lymphatic system’s ability to function normally, weakening your immune defenses.
The Two Main Types
All lymphomas fall into one of two broad categories: Hodgkin lymphoma and non-Hodgkin lymphoma. The distinction comes down to what the cancer cells look like under a microscope. If a pathologist spots a specific large, abnormal cell called a Reed-Sternberg cell, the lymphoma is classified as Hodgkin. If that cell is absent, it’s non-Hodgkin.
Hodgkin lymphoma almost always arises from B lymphocytes, one of the two main types of immune cells in the lymphatic system. Non-Hodgkin lymphoma is more varied. It can develop from B cells, T cells, or a third type called natural killer cells. About 85% of non-Hodgkin cases involve B cells.
Non-Hodgkin lymphoma is far more common. It also encompasses dozens of subtypes, which are grouped by how fast they grow:
- Low-grade (slow-growing): Follicular lymphoma, marginal zone lymphoma, and mantle cell lymphoma. These can sometimes go years without needing treatment.
- Intermediate-grade: Diffuse large B-cell lymphoma (the single most common subtype), primary mediastinal large B-cell lymphoma, and anaplastic large cell lymphoma.
- High-grade (fast-growing): Burkitt lymphoma and lymphoblastic lymphoma. These are aggressive and require prompt treatment.
Common Symptoms
The most recognizable sign of lymphoma is painless swelling of the lymph nodes, most often in the neck, armpits, or groin. Because swollen lymph nodes also happen with ordinary infections, many people initially dismiss the symptom. In lymphoma, the swelling tends to persist rather than resolve after a couple of weeks.
A specific cluster of symptoms known as “B symptoms” plays an important role in determining how advanced the disease is. These include drenching night sweats (enough to soak your sheets), unexplained fevers, and significant unintentional weight loss, typically defined as more than 10% of body weight over six months. Fatigue and itching are also common but not part of the formal B-symptom criteria.
How Lymphoma Is Diagnosed
Diagnosis usually starts with a physical exam checking for swollen lymph nodes, an enlarged spleen, or an enlarged liver. Blood tests can reveal elevated levels of certain enzymes and may also screen for viruses like HIV and hepatitis B and C, which are linked to a higher lymphoma risk.
The definitive step is a biopsy. A surgeon removes all or part of a swollen lymph node, and lab technicians examine the tissue under a microscope. They look for specific proteins on the surface of the cancer cells (called markers) and for DNA changes that identify the exact subtype. This matters because different subtypes behave differently and respond to different treatments.
Imaging scans, particularly PET, CT, and MRI, help map where the lymphoma has spread. A bone marrow biopsy, taken from the back of the hip bone, may also be done to check whether cancer cells have reached the marrow.
Staging: How Far It Has Spread
Lymphoma is staged from I to IV using a system that tracks how many lymph node regions are involved and whether the cancer has moved beyond the lymphatic system:
- Stage I: Cancer is in a single lymph node region.
- Stage II: Two or more lymph node regions are involved, but all are on the same side of the diaphragm (the muscle separating chest from abdomen).
- Stage III: Lymph node regions on both sides of the diaphragm are affected.
- Stage IV: The cancer has spread beyond the lymph nodes into organs such as the liver, lungs, or bone marrow.
Each stage also gets a letter. An “A” means no B symptoms are present. A “B” means the patient has night sweats, fevers, or significant weight loss. So a diagnosis of “Stage IIB,” for example, tells the treatment team both the geographic extent and the symptom burden.
Treatment Approaches
Treatment depends heavily on the type, subtype, and stage. Slow-growing non-Hodgkin lymphomas sometimes require nothing more than regular monitoring (called “watchful waiting”) until symptoms develop. Aggressive subtypes need treatment right away.
Chemotherapy combined with immunotherapy is the backbone of most lymphoma treatment. A common regimen for non-Hodgkin lymphoma pairs a targeted antibody with several chemotherapy drugs. The antibody attaches to a protein on the surface of B cells, flagging them for destruction by the immune system, while the chemotherapy kills rapidly dividing cells directly. For Hodgkin lymphoma, different chemotherapy combinations are standard, sometimes followed by radiation.
Radiation therapy targets specific lymph node regions and is frequently used for early-stage Hodgkin lymphoma or as a complement to chemotherapy. When radiation involves the chest area, especially in younger patients, the treatment team may use specialized techniques to reduce the dose reaching the heart and breast tissue.
Newer options include immune checkpoint inhibitors, which essentially remove the “brakes” that cancer cells put on the immune system, allowing the body’s own defenses to recognize and attack the lymphoma. These are used in Hodgkin lymphoma that has come back after initial treatment.
CAR-T Cell Therapy
For certain types of lymphoma that return after standard treatment or stop responding to it, a newer approach called CAR-T cell therapy is now available. In this treatment, doctors collect a patient’s own immune cells, genetically modify them in a lab to recognize a specific target on the cancer cells, and then infuse them back into the patient. Several CAR-T therapies are currently approved for specific lymphoma subtypes, including diffuse large B-cell lymphoma, follicular lymphoma, and mantle cell lymphoma. CAR-T therapy has produced strong responses even in patients who had run out of other options.
Survival and Outlook
Outcomes vary widely depending on the type and stage. Hodgkin lymphoma is one of the most curable cancers, particularly in younger patients and when caught early. Non-Hodgkin lymphoma has an overall five-year relative survival rate of about 74%, based on recent data from the National Cancer Institute. That number is an average across all stages and subtypes. Early-stage, slow-growing forms have much higher survival rates, while aggressive subtypes diagnosed at advanced stages bring that average down.
Even among aggressive lymphomas like diffuse large B-cell lymphoma, a significant proportion of patients achieve long-term remission with modern treatment. The range of available therapies has expanded substantially in the past two decades, and outcomes continue to improve as targeted and immune-based treatments become more refined.