Non-Hodgkin’s lymphoma (NHL or non-Hodgkin lymphoma) is a cancer that begins in the lymphatic system. It occurs when white blood cells called lymphocytes grow abnormally or uncontrollably. Non-Hodgkin’s lymphoma is more common than Hodgkin’s lymphoma, another cancer of the lymphatic system. The difference between Hodgkin’s lymphoma and Non-Hodgkin’s lymphoma is that Reed-Stenberg cells (a type of abnormal lymphocytes) are found in Hodgkin’s lymphoma but absent in Non-Hodgkin’s lymphoma. Also, there are different treatment approaches for Hodgkin’s and Non-Hodgkin’s lymphoma.
How common is Non-Hodgkin’s lymphoma?
Non-Hodgkin’s lymphoma (NHL) means a wide variety of cancers of the lymphatic system. It is the seventh most common cancer in the United States, accounting for around 4 percent of all cancers. More than 70,000 Americans are diagnosed with NHL every year while approximately 2.1 percent of people are diagnosed with the disease at some point during their lifetime. About 600,000 Americans are living with non-Hodgkin’s lymphoma, with about 20,000 cancer-related deaths per year attributed to this condition.
Causes of non-Hodgkin’s lymphoma
While the actual cause of non-Hodgkin’s lymphoma is still not fully known, it is believed that the cancer occurs when the body produces abnormal lymphocytes. Usually, lymphocytes have a predictable lifecycle in which old ones die and new ones replace them. But in non-Hodgkin’s lymphoma, old lymphocytes do not die and continue to grow into larger abnormal cells. The increased numbers of lymphocytes crowd the lymph nodes and cause them to swell.
Non-Hodgkin’s lymphoma can start in the:
- B-cells: These are white cells that fight body infections by producing antibodies. The antibodies neutralize any foreign invaders. Most NHL cases arise from B-cells and come in various sub-types such as follicular lymphoma, Burkitt lymphoma, mantle cell lymphoma, and diffuse B-cell lymphoma.
- T-cells: These are lymphocytes that kill foreign invaders directly. NHL occurs less often in T-cells. Common subtypes of T-cell NHL include cutaneous T-cell lymphoma and peripheral T-cell lymphoma.
Typical non-Hodgkin’s lymphoma involves the presence of abnormal lymphocytes in the lymph nodes, but can spread to other parts of the lymphatic system such as lymphatic vessels, adenoids, tonsils, thymus, bone marrow and spleen. In rare cases, non-Hodgkin’s lymphoma may spread to organs outside the lymphatic system.
Risk factors for Non-Hodgkin’s lymphoma
- Age: Non-Hodgkin’s lymphoma occurs more commonly in older people between 60 and 70 years or more. However, the disease may affect anyone.
- Weakened immunity: People with HIV/AIDS, auto-immune disorders or using immune-suppressing drugs are more likely to develop NHL.
- Certain viral and bacterial infections: The risk of non-Hodgkin’s lymphoma increases in people infected by Epstein-Barr virus, HIV and Helicobacter pylori (ulcer-causing bacteria).
- Certain chemicals: Exposure to chemicals such as pesticides for killing insects and weeds may increase the risk for NHL.
- Organ transplants: People who have organ transplants are at increased risk of NHL because they take immune suppressing medications.
Symptoms of non-Hodgkin’s lymphoma
Non-Hodgkin’s lymphoma is characterized by general symptoms common to noncancerous conditions. Therefore, you need to speak to your doctor if you have these symptoms.
- Swollen lymph nodes in your groin, armpits or neck.
- Constant fatigue.
- Abdominal swelling or pain.
- Coughing, chest pain or difficulty breathing.
- Drenching night sweats.
- Unexplained weight loss.
- Itchy skin or skin rash.
Diagnosis of non-Hodgkin’s lymphoma
Non-Hodgkin’s lymphoma refers to several types of cancer that affect the lymphatic system differently and require various treatments. To check for non-Hodgkin’s lymphoma and determine what kind it is, the following tests are used:
- Physical examination: The doctor will check your lymph nodes, spleen, liver and other areas for swelling or abnormality.
- Urine and blood tests: Various tests are used to rule out infection or other diseases and assess the function of your kidney and liver.
- Imaging: The doctor may use imaging techniques such as the X-ray, magnetic resonance imaging (MRI), computerized tomography (CT) scan or positron emission tomography (PET) to check for tumors.
- Lymph node biopsy: The doctor removes a lymph node to be examined under the microscope for cancer.
- Bone marrow biopsy: To check if the cancer has spread to the bone marrow, the doctor will insert a needle into the pelvic bone to collect a bone marrow sample for examination under the microscope for cancerous cells.
Staging non-Hodgkin’s lymphoma
Once Non-Hodgkin’s lymphoma has been diagnosed, the doctor will order tests to determine its size and how far it has spread. This is called staging. The doctor will do this to know how to plan treatment. NHL stages include:
- Stage I: Cancer is limited to a single lymph node or non-lymph node region.
- Stage II: Cancer has spread to two or more lymph node or non-lymph node regions on the same side of the diaphragm (muscle under the lungs).
- Stage III: Cancer has affected lymph nodes or non-lymph node regions below and above the diaphragm.
- Stage IV: Cancer has spread beyond the lymph nodes and reached organs such as lungs, bones and liver. This stage also describes cancer that has spread into distant lymph nodes or another organ away from the non-lymph node area of origin.
Treatment of non-Hodgkin’s lymphoma
The treatment for non-Hodgkin’s lymphoma depends on the patient’s age, overall health, preferences and the type and stage of the cancer. For example, if a lymphoma is slow-growing, less aggressive and has no problematic symptoms, the doctor may opt for a wait-and-see approach, giving no immediate treatment. The doctor will monitor the NHL closely through regular monthly checkups to ensure it is not advancing. But if the cancer is aggressive or causing symptoms, the doctor may recommend a treatment or combination of treatments such as chemotherapy, radiotherapy or biologic therapy.
- Chemotherapy: Drugs are given orally or by injection to kill cancer cells. The drugs may be given alone or combined with other drugs or other treatments.
- Stem cell transplant: This procedure allows the doctor to use higher doses of radiotherapy or chemotherapy with the aim of eradicating lymphoma cells that may not be killed with standard doses. Once cancer cells are killed, the doctor uses the transplant (stem cells from you or from a donor) to restore healthy cells to the body. If your stem cells are to be used, they must be harvested and frozen well before your treatment.
- Biologic therapy (immunotherapy): Certain drugs are used to boost your immune system so it can fight the cancer. For example, the drug rituximab (Rituxan) is a powerful monoclonal antibody which attaches to B-cells, making them more visible to your immune system and destroying them. Once abnormal B-cells are destroyed, the body produces new healthy B-cells to replace them.
- Radioimmunotherapy: Radioactive isotopes are added to drugs containing monoclonal antibodies, ensuring that the antibody attaches to cancer cells to deliver radiation directly to the cells. A good example of such drugs is ibritumomab tiuxetan (Zevalin) used to treat non-Hodgkin’s lymphoma.
- Radiation therapy (radiotherapy): High-powered energy beams such as X-rays or protons are used to kill cancerous cells and shrink tumors. While radiation can be delivered either by external beam radiation or internal radiotherapy (brachytherapy), non-Hodgkin’s lymphoma is commonly treated using external beam radiation. The radiation is delivered using a machine known as a linear accelerator for 5 days (Monday through Friday) a week for three to six weeks. The doctor can direct the radiation only to areas of the body known to have the cancer (involved field radiation), to all lymph nodes in the body in order to prevent the cancer from spreading (total nodal irradiation) or to the entire body (total body irradiation). Radiotherapy may be combined with chemotherapy and stem cell (or bone marrow) transplant for better efficacy.