Refractory marginal zone lymphoma is a challenging condition that occurs when this type of slow-growing blood cancer does not respond to treatment or when the disease returns after an initial period of improvement, presenting unique difficulties for patients and their healthcare teams.

Understanding Marginal Zone Lymphoma and Relapse

Marginal zone lymphoma, often called MZL, is a form of cancer that develops from special white blood cells known as B lymphocytes, which are cells that normally help your body fight infections. This cancer grows slowly compared to other types of lymphoma, which is why doctors often describe it as “indolent” or slow-growing. The disease gets its name because it starts in a specific area called the marginal zone, found at the edges of normal collections of immune cells in the body.^[1]

When doctors use the term “relapsed,” they mean that the cancer has come back after treatment had successfully put it into remission, which is a period when no signs of disease could be detected. On the other hand, “refractory” describes a situation where the lymphoma never really responded to treatment in the first place, meaning the cancer cells kept growing despite therapy, or any response achieved was disappointingly brief.^[2]

The reality for people with marginal zone lymphoma is generally quite positive at first. Many patients can live with this disease for years, and the typical survival time exceeds 10 years. When doctors combine standard treatments with specialized antibodies that target cancer cells, about 81 out of every 100 patients respond well to therapy. However, the picture changes dramatically for those whose disease doesn’t cooperate with treatment. Roughly 20 out of every 100 patients with MZL will see their disease come back or continue to worsen within just two years of starting treatment. For these individuals, the outlook becomes much more serious, with typical survival dropping to only 3 to 5 years.^[1]

How Common Is This Disease?

Marginal zone lymphoma ranks as the second most common type of slow-growing non-Hodgkin lymphoma, which is a broad category of blood cancers affecting lymphocytes. When looking at all cases of non-Hodgkin lymphoma diagnosed each year, marginal zone lymphoma accounts for somewhere between 5% and 15% of cases. In the United States alone, this translated to approximately 7,460 people receiving an MZL diagnosis in 2016.^[1][4]

Within the marginal zone lymphoma family, there are three distinct subtypes that differ based on where in the body they develop. The most common is extranodal MZL, also called MALT lymphoma, which starts in tissues outside the lymph nodes and represents about 70% of all MZL cases. Next is splenic MZL, which begins in the spleen and makes up roughly 20% of cases. Finally, nodal MZL starts in the lymph nodes themselves and accounts for about 10% of cases.^[1]

The typical person diagnosed with marginal zone lymphoma is around 67 years old when the disease is discovered, though this can vary somewhat depending on which specific subtype they have. Interestingly, MZL doesn’t show a strong preference for men or women overall. However, when researchers look at specific types of the disease or where it develops in the body, they sometimes notice that women are affected slightly more often than men in certain situations.^[1][7]

What Causes Marginal Zone Lymphoma?

The development of marginal zone lymphoma is closely tied to situations where the immune system becomes activated for extended periods. In many cases, chronic infection with bacteria or viruses triggers ongoing immune responses that, over time, can lead to cancerous changes in B cells. This long-term stimulation causes these immune cells to multiply and change in ways that eventually result in lymphoma.^[4]

One of the clearest examples of this connection involves stomach MALT lymphoma, which accounts for more than 30% of all MALT cases. About two-thirds of people with this type of lymphoma have a chronic infection with Helicobacter pylori, a bacterium that causes inflammation in the stomach lining. This persistent inflammation creates an environment where lymphoma can develop over many years.^[4]

Other infections have also been linked to marginal zone lymphoma in different parts of the body. Hepatitis C virus infection can lead to various forms of MZL. A bacterium called Chlamydophila psittaci has been associated with lymphoma in the tissue around the eye and in the conjunctiva, which is the clear covering of the eyeball. Similarly, the bacterium Borrelia burgdorferi, which causes Lyme disease, has been connected to skin lymphomas, while Achromobacter xylosoxidans has been linked to lung involvement.^[4]

Beyond infections, certain autoimmune diseases create a higher risk for developing marginal zone lymphoma. These are conditions where the immune system mistakenly attacks the body’s own tissues, creating chronic inflammation similar to what happens with persistent infections. Sjögren syndrome, an autoimmune disease that affects moisture-producing glands, raises the risk of developing lymphoma in the salivary glands. Similarly, Hashimoto thyroiditis, which affects the thyroid gland, increases the likelihood of thyroid lymphoma. Other autoimmune conditions like systemic lupus erythematosus also appear to elevate MZL risk.^[4]

Risk Factors for Developing the Disease

Several factors can increase a person’s chances of developing marginal zone lymphoma beyond the direct causes mentioned above. Having a family history of lymphoma stands out as a particularly important risk factor. If blood relatives have had lymphoma or other blood cancers, your own risk increases, suggesting that inherited genetic factors play some role in who develops this disease.^[4]

Researchers have also discovered more specific risk factors for different MZL subtypes through careful epidemiological studies. For nodal marginal zone lymphoma, working as a metalworker appears to increase risk significantly, with affected individuals having roughly 3.6 times higher odds of developing this cancer compared to people in other occupations. For splenic MZL, having asthma raises risk by about 2.3 times, and using hair dye is associated with a striking 6.5 times higher risk, though scientists are still working to understand exactly why these connections exist.^[4]

The genetic landscape also plays a role. Scientists conducting large-scale genetic studies have identified specific variations in genes related to the immune system that can influence a person’s susceptibility to marginal zone lymphoma. In particular, variations near genes called BTNL2 and HLA-B, which are part of the body’s system for recognizing foreign substances, have been linked to increased MZL risk. This finding provides the first clear evidence that inherited differences in immune function can make some people more vulnerable to developing this disease.^[4]

Recognizing the Symptoms

The symptoms of marginal zone lymphoma vary considerably depending on where in the body the disease develops, which makes sense given that this cancer can arise in many different tissues. Because MZL is a slow-growing cancer, symptoms often develop gradually over time rather than appearing suddenly, and some people may not experience any symptoms at all initially.^[4]

When marginal zone lymphoma develops in lymph nodes, the most common sign is swelling of these small immune organs, which you might notice as lumps under the skin in areas like the neck, armpits, or groin. These swollen nodes are typically painless, though they can sometimes cause discomfort if they grow large enough to press on nearby structures. An enlarged spleen, which doctors call splenomegaly, is another common finding, particularly in splenic MZL. You might not be able to feel this yourself, but your doctor can detect it during a physical examination.^[3]

For MALT lymphoma, which develops outside the lymph nodes, symptoms depend entirely on which organ is affected. If the disease develops in the stomach, you might experience indigestion, stomach pain, nausea, or a feeling of fullness after eating only small amounts of food. Lymphoma affecting the lungs might cause persistent cough, shortness of breath, or chest discomfort. Eye or eyelid involvement could lead to swelling, a sensation of something in the eye, or visual changes. Thyroid lymphoma might present as a lump in the neck or difficulty swallowing.^[4]

Some patients experience what doctors call “B symptoms,” which are systemic effects of the lymphoma that include unexplained fever, drenching night sweats that require changing clothes or bedding, and unintentional weight loss of more than 10% of body weight over six months. Fatigue is another common complaint that can significantly impact quality of life. These symptoms don’t necessarily mean the disease is more advanced, but they do provide important information that helps doctors plan treatment.^[4]

Prevention Strategies

Because marginal zone lymphoma is strongly linked to chronic infections and autoimmune diseases, preventing or treating these underlying conditions represents the most direct way to reduce MZL risk. For stomach MALT lymphoma specifically, identifying and treating Helicobacter pylori infections before they lead to lymphoma could theoretically prevent many cases. People with chronic heartburn or stomach problems should consider testing for this bacterium and pursuing treatment if it’s found.^[4]

For individuals with hepatitis C virus infection, receiving antiviral treatment not only protects liver health but also reduces the risk of developing various forms of marginal zone lymphoma. Modern hepatitis C treatments are highly effective and can often completely clear the virus from the body. If you have hepatitis C and then develop MZL, treating the viral infection first can sometimes lead to improvement or even disappearance of the lymphoma symptoms, allowing you to potentially avoid cancer treatment altogether.^[8]

People with autoimmune diseases like Sjögren syndrome, Hashimoto thyroiditis, or systemic lupus erythematosus should maintain regular follow-up with their healthcare providers. While having these conditions does increase lymphoma risk, the vast majority of people with autoimmune diseases never develop cancer. However, being aware of this small increased risk allows you and your doctor to promptly investigate any new or unusual symptoms.^[4]

For the occupational and environmental risk factors that have been identified, such as metalworking or hair dye use, the evidence is still being studied. While these associations exist in research studies, scientists haven’t yet determined whether avoiding these exposures would actually reduce lymphoma risk, or whether the connection is more complex than it appears.

Finally, because family history matters, if you have close relatives who have had lymphoma or other blood cancers, it’s worth mentioning this to your doctor. While there’s no specific screening test for marginal zone lymphoma recommended for people with family history alone, your healthcare team can remain alert to any concerning signs or symptoms you might develop.

How the Disease Affects the Body

Understanding what happens in marginal zone lymphoma at a cellular and molecular level helps explain why certain treatments work and how the disease causes problems in the body. At its core, MZL involves the uncontrolled growth of B lymphocytes, which are specialized white blood cells that normally produce antibodies to fight infections. In marginal zone lymphoma, these cells accumulate in tissues where they shouldn’t be in such large numbers, forming masses that can interfere with normal organ function.^[4]

The lymphoma cells in MZL typically arise from memory B cells, which are immune cells that have already encountered antigens (foreign substances) and are designed to mount quick responses if they see those antigens again. In healthy people, these cells live in the marginal zone of lymphoid organs, which is the region between the inner and outer parts of structures like lymph nodes or the spleen. When chronic stimulation occurs through infection or autoimmunity, these cells receive repeated signals to multiply and become active, and somewhere in this process, genetic mistakes accumulate that transform them into cancer cells.^[7]

Several key signaling pathways inside cells become abnormally activated in marginal zone lymphoma. One of the most important is the B-cell receptor pathway, which normally helps B cells recognize foreign invaders. In MZL, this pathway sends constant “grow and divide” signals even when there’s no real threat to fight. This happens through various genetic alterations that can include chromosomal rearrangements (where pieces of different chromosomes swap places) or mutations in specific genes.^[4]

Another critical pathway that goes awry in MZL involves NF-kB, a protein complex that acts like a master switch controlling inflammation and cell survival. Normally, NF-kB activation is tightly controlled and temporary, turning on when needed and off when the job is done. In marginal zone lymphoma, genetic changes can cause permanent activation of this pathway. These alterations include specific chromosomal translocations like t(11;18) or t(1;14), which bring together genes that shouldn’t normally interact, or mutations that inactivate a gene called A20 that normally puts the brakes on NF-kB signaling.^[4]

The disease can remain localized to one area of the body for long periods, which is why many MALT lymphomas are found at early stages affecting only one organ or region. However, about 20% of cases have already spread to multiple sites by the time of diagnosis. When spread occurs, it tends to follow patterns where the lymphoma cells travel to other similar tissue types. For instance, stomach MALT lymphoma might spread to other parts of the digestive system, or lymphoma in one salivary gland might appear in others.^[4]

In some cases, marginal zone lymphoma can undergo what doctors call transformation, changing from a slow-growing cancer into a more aggressive type called diffuse large B-cell lymphoma. This transformation happens in a minority of patients but represents a serious complication because the faster-growing cancer requires more intensive treatment. Transformation is associated with additional genetic changes, particularly mutations in a gene called TP53 or alterations in genes like MYC that normally control cell division.^[4]

When lymphoma cells accumulate in large numbers, they cause problems by physically crowding out normal cells and disrupting organ function. In the bone marrow, they can interfere with production of normal blood cells, potentially leading to anemia (low red blood cells causing fatigue), low white blood cell counts (increasing infection risk), or low platelet counts (causing easy bruising or bleeding). In solid organs like the stomach or lungs, the tumor masses can cause the specific symptoms related to that organ’s function being impaired.

Treatment Approaches for Relapsed and Refractory Disease

When marginal zone lymphoma comes back after initial treatment or never responds adequately in the first place, doctors have several options to consider. The choice of treatment depends on many factors including the patient’s age, overall health, what treatments they’ve already received, how long any previous remission lasted, and whether they’re experiencing symptoms from the disease.^[2]

For many patients with relapsed or refractory MZL, the same types of therapies used for newly diagnosed disease can be tried again, especially if a significant amount of time has passed since the previous treatment. This might include targeted antibodies like rituximab (also known by brand names like Rituxan), which attaches to proteins on the surface of lymphoma cells and marks them for destruction by the immune system. Rituximab can be used alone or combined with chemotherapy drugs.^[2]

A combination specifically mentioned for relapsed/refractory MZL is called R², which pairs rituximab with lenalidomide (brand name Revlimid). Lenalidomide is an immunomodulator, meaning it works by modifying how the immune system functions, helping it attack cancer cells more effectively while also having direct effects on the lymphoma cells themselves.^[2]

In recent years, a new class of drugs called Bruton’s tyrosine kinase inhibitors, or BTK inhibitors, has emerged as an important option for people whose MZL has relapsed or proven refractory. These medications target a specific enzyme involved in B-cell receptor signaling, essentially blocking one of the abnormal growth signals that keeps lymphoma cells alive and multiplying. Two BTK inhibitors have shown particular promise: ibrutinib (brand name Imbruvica) and zanubrutinib (brand name Brukinsa or BRUKINSA).^[2][8]

In a pivotal clinical study of ibrutinib for relapsed/refractory MZL, researchers found that 48 out of 100 patients responded to the treatment, meaning their tumors shrank or disappeared. About 3 out of 100 patients had a complete response where all detectable cancer vanished. The median time before the disease progressed again was 14.2 months, and at the time the study results were published, more than half the patients were still alive, with follow-up continuing. These results were strong enough that the U.S. Food and Drug Administration approved ibrutinib specifically for treating relapsed or refractory marginal zone lymphoma in 2017.^[7]

Beyond these systemic treatments that travel throughout the body, some patients with localized relapsed disease might benefit from radiation therapy, which uses high-energy beams to kill cancer cells in a specific area. For certain types of MALT lymphoma that remain associated with active infection, treating the underlying infection again might help control the lymphoma. For example, if stomach MALT lymphoma returns and Helicobacter pylori is still present or has come back, antibiotics directed at this bacterium could potentially help.^[8]

In some situations, particularly for younger patients with relapsed disease that’s difficult to control, doctors might consider stem cell transplantation. This intensive procedure involves collecting healthy blood-forming stem cells, then giving high doses of chemotherapy to eliminate the lymphoma, followed by returning the stem cells to help the bone marrow recover. While this approach can sometimes produce long-lasting remissions, it carries significant risks and requires careful patient selection.^[8]

Clinical trials investigating new drugs and combinations offer another important option for patients with relapsed or refractory MZL. These studies test experimental treatments that might work better than current options or have fewer side effects. Participating in a clinical trial not only gives patients access to potentially beneficial new therapies but also helps advance scientific understanding in ways that could help future patients.