Lymphoma

Like our blood vessels, we have a network of small vessels called the lymphatic system, carrying fluid and fats around the body. Throughout this network are small swellings called lymph nodes, which filter the lymphatic fluid and where lymphocytes (white blood cells) mature.

Cancerous lymphoma cells usually start in the lymph nodes and can spread to the bone marrow and bloodstream.

The image below shows the location of the lymph nodes where lymphoma most commonly develops.

Image credit: CRUK via Wikimedia Commons(external link)

Lymphoma is not a type of leukaemia, although it has similarities. The main difference is that lymphoma starts in the lymph nodes and leukaemia starts in the bloodstream or bone marrow. They are treated as separate conditions. 

Each year in Aotearoa New Zealand over 1000 people are diagnosed with lymphoma, making it the 6th most common type of cancer. The majority of these people (at least 85%) have non-Hodgkin lymphoma.

Lymphoma begins in developing lymphocytes (white blood cells), that have undergone a malignant (cancerous) change. Instead of maturing properly, these cells grow and multiply in an uncontrolled way in the lymph node. They may move out of the node and spread to the bone marrow or into the bloodstream. As the cancerous cells can grow fast within the bone marrow, they may overcrowd the space inside. This disrupts the production of normal blood cells which leads to anaemia and makes you vulnerable to infection. 

There are several different types and subtypes of lymphoma but most fall into the category of Hodgkin and non-Hodgkin lymphoma.

The table below shows the differences.

The cause of lymphoma is not completely understood. There are several factors which seem to affect its development. In most instances, the cause of the disease remains unknown. 

The factors discussed below have been found to increase the risk, however having been exposed to 1 or more of these doesn’t mean that you’ll definitely develop lymphoma. If you are concerned about any of these you should talk to your healthcare provider.

• Genetic factors: People with genetic and chromosomal conditions, or a history of an immunodeficiency have a greater risk of developing lymphoma. Genetics appear to play a role as first degree relatives of someone who has Lymphoma are at a higher risk of developing it themselves. 
• Radiation: Lymphoma occurs at higher than average rates among people exposed to intense radiation and nuclear contamination. People who have received radiation therapy for the treatment of other diseases in the past can also be at a higher (but still low) risk of developing a radiotherapy induced secondary malignancy (RISM). If you have undergone radiation, this would be discussed with your radiation oncologist prior to starting treatment. Typically, these cancers emerge within a few years of having radiation treatment. Following this, the likelihood of developing another cancer gradually decreases over time.
• Chemicals: People exposed to industrial chemicals, particularly herbicides and pesticides have an increased risk of developing lymphoma. Some types of cytotoxic (toxic to cells) drugs used in the treatment of autoimmune diseases, organ transplant patients and cancer treatments also increase the risk of developing lymphoma.
• Viruses: In certain areas of the world (eg, southwest Japan, parts of Africa and the Caribbean) a particular type of lymphoma has been shown to occur in local residents who've been exposed to a virus known as Human T-cell Lymphotropic Virus (HTLV-1). However, only a small number of people who have had this infection eventually develop lymphoma. Epstein-Barr virus and HIV have also been associated with an increased risk of developing lymphoma.

Often people with lymphoma have no clear symptoms prior to diagnosis or may have noticed a firm lump or node somewhere in their body. Diagnosis is often made from abnormal findings in a blood test or through investigations for other illnesses.

However, if you have lymphoma you may feel very tired, get night sweats and have a reduced appetite causing you to lose weight. These are common symptoms that can often be explained by other things, but if you have any concern about them you should see your healthcare provider.

You may also experience symptoms linked to low levels of certain blood cells. For example:

• red blood cell shortage (low haemoglobin) may lead to fatigue, shortness of breath and pale skin colouring
• insufficient or ineffective white blood cells (neutropenia or lymphocytosis) may lead to repeated or serious infections
• a decrease in the number of platelets (thrombocytopenia) may lead to increased bleeding and bruising in the skin, nosebleeds, heavy menstrual bleeding and rectal bleeding.

However, the symptoms of lymphoma are typical of many other diseases and for some types of lymphoma, there’s no evidence the disease is present until it reaches an advanced stage.

Lymphoma is diagnosed using either a blood test or a bone marrow test (bone marrow biopsy). When a blood sample is analysed, the number of white blood cells, red blood cells and platelets are counted. Following this, other tests (eg, CT, MRI or PET scanning) may be done to help with staging. Staging is the process used to find out how far a cancer has spread. 

The blood count is considered abnormal if any of the following are found:

• a low platelet count
• a low number of red blood cells
• a low count of mature white blood cells
• a high number of immature or prematurely released white blood cells, called blasts.

If a firm node is felt under the skin, or a concerning mass is found on imaging that's just beneath the skin, a biopsy may be taken. Most commonly, this is a fine needle aspiration where a very small needle is used to draw out a sample from the mass. This is helpful for confirming the diagnosis.

Many tests and investigations may be necessary to completely confirm a diagnosis and also to establish the best combination of therapies.

Treatment depends on the individual patient and the type and location of the lymphoma. It may include surgery, chemotherapy, radiotherapy and stem cell or bone marrow transplant.

Treatment aims to remove the harmful cancer cells so that the healthy cells can grow back in your bone marrow and blood. 

Treatment may cure lymphoma, particularly in Hodgkin's lymphoma or when the disease is detected in its earlier stages. 

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Cancer support groups(external link) Cancer Society NZ
NZ Cancer Services(external link) Healthpoint NZ
Lymphoma and blood cancer NZ(external link) Resources and booklets in multiple languages
Patient and family support(external link) Leukaemia & Blood Cancer Foundation NZ