Non-Hodgkin's lymphoma

What is non-Hodgkin's lymphoma?

Non-Hodgkin's lymphoma is one of the two main types of lymphoma, a cancer that develops in the lymphatic system. The other type is Hodgkin's lymphoma. The difference between the two can be seen by looking at the cancer cells under a microscope. In non-Hodgkin's lymphoma, a specific cell type called a Reed-Sternberg cell isn't present.

While its exact cause is unknown, certain factors can increase a child's risk of developing this cancer, including a weakened immune system and past infection with the Epstein-Barr virus (a common herpesvirus found worldwide). Non-Hodgkin's lymphoma affects boys almost three times more often than girls, and it's more common in white children than in children of other races.

Types of non-Hodgkin's lymphoma

There are many types of non-Hodgkin's lymphoma, but the three main ones affecting children are aggressive mature B-cell non-Hodgkin's lymphoma, lymphoblastic lymphoma and anaplastic large cell lymphoma.

Aggressive mature B-cell non-Hodgkin's lymphoma

This type of non-Hodgkin's lymphoma develops from white blood cells called B lymphocytes, or B cells, and it spreads quickly. There are several subtypes:

• Diffuse large B-cell lymphoma. The most common type of non-Hodgkin's lymphoma, diffuse large B-cell lymphoma occurs more often in teens than in younger children. These tumors grow rapidly in lymph nodes and often spread to the spleen, liver, bone marrow and other organs.
• Small noncleaved cell lymphoma. Also called Burkitt lymphoma, small noncleaved cell lymphoma is common – but different – in Africa and North America. In Africa, this cancer is almost always associated with the Epstein-Barr virus and often occurs with a jaw tumor and central nervous system disease (meaning the brain or spinal cord is affected). In North America, it's rarely associated with the Epstein-Barr virus, and it arises in the abdomen and often spreads to bone marrow.
• Primary mediastinal B-cell lymphoma. This subtype tends to develop behind the breastbone. It's more common in older adolescents than in young children.

Lymphoblastic lymphoma

Lymphoblastic non-Hodgkin's lymphoma accounts for about 35% of lymphoma cases in children. This disease typically involves T cells (another type of lymphocyte), though it can involve B cells. It usually occurs with a tumor in the chest and swollen lymph nodes. Sometimes the bone marrow and central nervous system are also affected.

Anaplastic large cell lymphoma

This type of non-Hodgkin's lymphoma generally begins in T cells and can involve the skin, lymph nodes, lungs, testicles, muscles and digestive tract.

In many children, non-Hodgkin's lymphoma is already extensive when diagnosed. About one-third of cases originate in the neck or chest, one-third in the abdomen and one-third elsewhere in the body.

Symptoms of non-Hodgkin's lymphoma

Many symptoms of non-Hodgkin's lymphoma in children can also be caused by other conditions, such as infections. Nevertheless, your child should be evaluated by a doctor if they have any of the following symptoms:

• Abdominal pain and swelling
• Swollen lymph nodes
• Persistent change in bowel habits
• Fever for no known reason
• Sweating, especially at night
• Weight loss for no known reason

When the cancer is in the abdomen, the area can become very swollen, sometimes resembling a pregnant belly. When the cancer causes lymph tissue near kidneys or intestines to swell, urine or feces passing through the area may become blocked, causing abdominal pain.

If the chest is involved, the child's head and neck may swell and they may have trouble breathing. The cancer can press on the superior vena cava (SVC), the large vein that carries blood from the head and arm back to the heart, and that pressure can cause the head, arm and upper chest to turn reddish and eventually bluish. Known as SVC syndrome, this condition can affect the brain and be life-threatening. Children with SVC syndrome need immediate treatment.

Diagnosis of non-Hodgkin's lymphoma

Your child's doctor may order a number of diagnostic tests, including imaging studies, such as a CT scan or PET scan. To confirm the diagnosis, your child will have a biopsy, which is the removal of a tissue sample that's then examined under a microscope in the lab to see whether cancer cells are present.

Your child's doctor will choose the biopsy technique that best suits your child's condition. The goal is getting enough tissue to make an accurate diagnosis as quickly as possible while minimizing discomfort and the risk of complications. Types of biopsies include:

• Fine needle aspiration (FNA) biopsy. A very thin needle is passed through the skin to draw out a sample of the tumor. The main advantage of FNA is that it doesn't require surgery; a drawback is that sometimes the amount of tissue obtained is inadequate for analysis.
• Excisional or incisional biopsy. In an excisional biopsy, the surgeon removes an entire lymph node for analysis. If the node is near the skin's surface, this is a simple operation that can be done after numbing the skin. If the node is inside the chest or abdomen, your child will need to be under general anesthesia (completely asleep). In an incisional biopsy, the surgeon removes a small part of a large tumor.
• Bone marrow aspiration and bone marrow biopsy. This test involves obtaining a small amount of bone marrow tissue and fluid. The sample is usually taken from the back of a pelvic bone. The bone is numbed, and the child receives additional medication to control pain or induce sleep. A needle is passed through the bone's outer layer into the marrow and the sample is removed. This test can be used to see whether cancer is present and also to assess how far cancer has spread.
• Chest (pleural) or abdominal (peritoneal) fluid examination. If a patient's lymphoma has spread to the membranes that line the chest or abdomen, fluid can build up. This fluid can be removed by passing a needle through the skin into the chest or abdomen, and a sample can be checked for cancer cells. The skin is numbed beforehand.

Staging of non-Hodgkin's lymphoma

The following stages are used specifically for childhood non-Hodgkin's lymphomas:

Stage 1

To be classified as stage 1, the cancer must:

• Be present in just one lymph node group or in only one area outside of the lymph nodes
• Not be present in the abdomen or the mediastinum (the area between the lungs)

Stage 2

To be classified as stage 2, one of the following criteria must be met:

• Cancer is found in one area outside the lymph nodes as well as nearby lymph nodes.
• Cancer is found in two or more areas on the same side of the diaphragm (the thin muscle that separates the chest from the abdomen) and possibly in nearby lymph nodes.
• The cancer started in the stomach or intestines (possibly spreading to nearby lymph nodes) and can be surgically removed.

Stage 3

To be classified as stage 3, one of the following criteria must be met:

• Cancer is found in at least one area above the diaphragm and at least one area below it.
• The cancer started in the chest.
• The cancer started in the abdomen, has spread through the abdomen and cannot be entirely removed by surgery.
• Cancer is found in the area around the spine.

Stage 4

In stage 4, cancer is found in the bone marrow, the brain or the fluid that surrounds the brain and spinal cord (cerebrospinal fluid). It may have spread to other organs.

Recurrent

This is when cancer comes back after it has been treated. It may recur in the area where it first appeared or in another part of the body.

Treatment of non-Hodgkin's lymphoma

Non-Hodgkin's lymphoma in children has a cure rate of about 70%. We have three main approaches to treatment.

Chemotherapy

Chemotherapy, the primary treatment for non-Hodgkin's lymphoma, uses drugs to kill cancer cells and shrink tumors. Chemotherapy is called a systemic treatment because the drugs enter the bloodstream and can therefore kill cancer cells throughout the body.

Chemotherapy may be taken orally (as pills) or injected into a vein (intravenous administration) or into muscle. For certain lymphomas that have spread to the brain or may do so, some chemo drugs can be injected into the cerebrospinal fluid.

Radiation therapy

Radiation therapy uses a high-dose, focused X-ray beam to kill cancer cells and shrink tumors. It's very effective in treating lymphoma.

Bone marrow transplant

Sometimes lymphoma cells become resistant to radiation therapy or chemotherapy. Extra-high doses of chemotherapy may then be necessary to treat the cancer.

Because these high chemo doses destroy bone marrow, some of the patient's marrow is taken from their bones before their chemo begins. The marrow is frozen, and after the patient finishes the course of high-dose chemotherapy (with or without radiation therapy), their collected marrow is thawed and returned by needle into a vein so that it can replace the destroyed marrow.

This type of bone marrow transplant is called an autologous transplant because the patient's own cells are used (auto means "self" or "same"). If the marrow is taken from another person, the transplant is called an allogeneic transplant (allo means "other").