The lymphatic system is an extensive network of tubular vessels and glands (nodes) that collects excess fluid and matter from the tissues and deposits them into the bloodstream.
It also contains white blood cells called lymphocytes, which protect the body from infections.
There are two types of lymphocytes produced by the bone marrow – B-cells and T-cells.
B-cells mature in the bone marrow and T-cells travel through the bloodstream to the thymus gland, which is located between the lungs and sternum, to mature there.
B-cells fight infective organisms by producing antibodies.
There are two types of T-cells – killer cells, which kills cells that are already infected, and helper cells, which stimulate B-cells to produce antibodies.
The B-cells multiply abnormally in Hodgkin lymphoma and collect in parts of the lymphatic system like the nodes.
Later, it spreads to the bone marrow, spleen, liver, skin and lungs.
There are two types of Hodgkin lymphoma – classic Hodgkin lymphoma, which comprises about 95% of cases, and nodular lymphocytic predominant Hodgkin lymphoma, which comprises about 5%.
Hodgkin lymphoma can occur at any age but it is more common in young adults and senior citizens, with a slight preponderance in men.
Although the cause is unknown, the risk factors include conditions that weaken the immune system (such as HIV or treatment with immunosuppressants), previous exposure to Ebstein-Barr virus, previous non-Hodgkin’s lymphoma and obesity.
The most common feature is a painless swelling in the neck, armpit or groin. Others include unexplained weight loss, night sweats, fever, persistent cough and/or generalised skin itch.
If the liver and/or spleen is affected, there may be abdominal swelling or indigestion.
If the bone marrow is involved, there may be an increased likelihood of infections, abnormal or excessive bleeding, and/or tiredness.
A definitive diagnosis is made by the biopsy of a lymph node.
This involves removal of part or whole of a lymph node under local anaesthetic, followed by microscopic examination of the lymph node by a pathologist.
If the biopsy confirms the diagnosis, additional tests are carried out to determine the extent of the condition.
These tests include tests of the blood count, liver and kidney function; chest x-ray to check if it has spread to the lungs; bone marrow biopsy to check if it has spread to the bone marrow; and computerised tomography (CT) scan, magnetic resonance imaging (MRI) and/or positron emission tomography (PET) scan to check if it has spread to other parts of the body.
The results of the investigations enable a determination of the spread of the condition, the process of which is termed “staging”.
In stage 1, the condition is limited to one group of lymph nodes either above or below the diaphragm, which is the muscle below the lungs and just above the abdominal cavity.
In stage 2, two or more lymph node groups are affected, either above or below the diaphragm.
In stage 3, the lymph node groups above and below the diaphragm are affected.
In stage 4, there is spread through the lymphatic system, with the involvement of organs like the spleen, liver or bone marrow.
Hodgkin lymphoma can usually be treated successfully with chemotherapy alone, or with chemotherapy followed by radiotherapy.
Sometimes, chemotherapy may be combined with steroids.
The considerations in planning treatment include the affected person’s age, general health, individual preferences and the type of Hodgkin lymphoma.
Chemotherapy involves the administration of medicines through a drip into a vein, usually on an out-patient basis, for a few months.
As with all chemotherapy, there will be side effects such as nausea, vomiting, diarrhoea, poor appetite, hair loss and infertility.
Should the chemotherapy lead to damage to the bone marrow, there will be an increased likelihood of infections, tiredness, easy bruising and bleeding, and breathlessness.
If this occurs, treatment may be delayed to allow time for the bone marrow to recover and produce more healthy cells.
If the chemotherapy is unsuccessful or the condition recurs, higher doses of chemotherapeutic medicines may be prescribed.
This increases the likelihood of bone marrow damage and the need for a bone marrow transplant.
If cure is unlikely, oral chemotherapy may be prescribed for relief of symptoms.
Radiotherapy is often used in the treatment of the early stages of Hodgkin lymphoma.
The part of the body where the condition is found is treated on an out-patient basis.
Whilst the radiotherapy is painless, the side effects include nausea, vomiting, poor appetite, tiredness and symptoms related to the part of the body that is treated, such as sore throat if radiotherapy is applied to the neck.
Steroids are prescribed in more advanced cases or when initial chemotherapy has not worked.
The side effects of steroids include increased appetite, weight gain, agitation and sleep problems.
The side effects of chemotherapy, radiotherapy and steroids are usually temporary and will resolve when treatment is completed.
It is important to attend the follow-up appointments as their objective is the monitoring of recovery and early detection of a recurrence of the condition.
The interval between the appointments will be frequent initially, but it will lengthen with the passage of time.
Although Hodgkin lymphoma can spread rapidly, it is one of the most easily treatable cancers, with marked improvement in the survival rates in the past few decades, largely due to advances in treatment.