Hodgkin's lymphoma

Overview

Lymphoma is the third most common childhood cancer. It is cancer of the lymphatic system, which is made up of thin tubes that branch like blood vessels into all parts of the body. These lymph vessels carry lymph, a colorless, watery fluid containing white blood cells called lymphocytes. Along the network of vessels are lymph nodes, groups of small, bean-shaped organs that make and store infection-fighting cells.

There are clusters of lymph nodes in the underarm, groin, neck and abdomen. The lymph system also includes the spleen, the thymus and the tonsils. Because the lymph system is so extensive, lymphoma can start in many locations and spread to almost any organ or tissue.

There are two types of lymphoma — Hodgkin's and non-Hodgkin's. The cause for both diseases is unknown and it occurs in one child in 10,000. Hodgkin's disease typically affects those age 14 and older.

Hodgkin's lymphoma often occurs in one or more groups of lymph glands, most commonly in the neck. The first symptom is usually swollen glands. Often, the cancer is limited to a small number of closely related glands. In half of the children affected, it spreads to the chest.

The disease occurs in three distinct forms:

• Childhood: 14 years of age and younger
• Young adult: 15 to 34 years of age
• Older adult: 55 to 75 years of age

Hodgkin's disease peaks in young adults and again in those over 50 years of age. It is slightly more common in males than females, and is more common in Caucasians. This disease is very rare in children younger than 5 and tends to cluster in families. The main malignant cell of Hodgkin's lymphoma is the "Reed-Sternberg" cell that originates from B or T cells, cells that contain antibody molecules. Several types of Hodgkin's disease also are associated with the Epstein-Barr virus, a member of the herpes virus family and one of the most common human viruses.

Types of Hodgkin's lymphoma

Four types of Hodgkin's disease are:

• Nodular Sclerosing — This accounts for about 40 percent of all Hodgkin's disease and for 70 percent of the Hodgkin's cases in adolescents. This is the only form of Hodgkin's that is more prevalent in women. It can involve the lower cervical lymph nodes.
• Mixed Cellularity — This represents about 30 percent of Hodgkin's disease and usually affects children less than 10 years of age. This condition is usually an advanced disease.
• Lymphocyte Predominance — This accounts for 10 to 15 percent of Hodgkin's disease and is predominant in males and younger patients. The condition usually is localized and has the best likelihood of a good outcome.
• Lymphocyte Depleted — This condition is rare in children and more common in HIV-positive adults. It is usually a widespread disease.

Signs & symptoms

The first symptom of Hodgkin's lymphoma is usually swollen lymph glands. In a minority of children, there is high fever, weight loss and night sweats. These symptoms are more common if the cancer is extensive.

Diagnosis

Many of the symptoms of Hodgkin's lymphoma are general in nature and could be caused by other conditions such as infections.

Your child's doctor may request a number of diagnostic tests, including:

Computed tomography (CT or CAT) scan

This diagnostic imaging procedure provides detailed images of the body, including the bones, muscles, fat and organs.

Positron emission tomography (PET) scan

This is a nuclear medicine test in which a radioactive compound is injected and shows the areas of malignancy in the body.

Biopsy

A biopsy, which involves the removal of a sample of tissue to see whether cancer cells are present, is necessary to confirm the diagnosis. There are several kinds of biopsies. Your child's doctor will choose the one best suited for your child. The goal is to get enough tissue to make an accurate diagnosis as quickly as possible with the fewest side effects.

• Fine Needle Aspiration (FNA) Biopsy— For this test, a very thin needle is used to draw up a small amount of tissue from the tumor. The main advantage of FNA is that it doesn't require surgery; a drawback is that in some cases not enough tissue can be removed.
• Excisional or Incisional Biopsy — In an excisional biopsy, the surgeon removes the entire lymph node. In an incisional biopsy, the surgeon removes a small part of a large tumor. 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, then your child will need general anesthesia, medicine that causes your child to sleep.
• Bone Marrow Aspiration and Biopsy — This test involves obtaining a small amount of bone marrow tissue and fluid. Usually the sample is taken from the back of the pelvic bone. The bone is numbed and the child is given medicine to reduce pain or even cause sleep. A needle is put through the outer bone into the marrow and the sample is removed. This test can be used to see if cancer is present and also to help see how far the cancer has spread.
• Chest (Pleural) or Abdominal (Peritoneal) Fluid Examination — If the lymphoma has spread to the membranes that line the chest or abdominal cavities, fluid can build up. This fluid can be removed by placing a needle through the skin into the chest, for a pleural examination, or abdomen, for a peritoneal examination. The fluid is checked to see if cancer cells are present. The skin is numbed before the test is done.

Staging

The following stages are generally used for childhood lymphomas:

• Stage I — Cancer is found in only one lymph node area or in only one area or organ outside of the lymph nodes.
• Stage II — Cancer is found in two or more lymph node areas on the same side of the diaphragm, the thin muscle under the lungs that helps with breathing, or cancer is found in only one area or organ outside the lymph nodes and in the lymph nodes around it.
• Stage III — Cancer is found in lymph node areas on both sides of the diaphragm. The cancer also may have spread to an area or organ near the lymph node or to the spleen.
• Stage IV — Cancer has spread in more than one spot to one or more organs outside of the lymph system. Cancer cells may or may not be found in the lymph nodes near these organs and may even involve lymph nodes far from the organ involved.
• Recurrent — Recurrent disease means that the cancer has come back after it has been treated. It may come back in the area where it first started or in another part of the body.

Treatment

The most common treatments for Hodgkin's disease are radiation or chemotherapy and sometimes a combination of the two. Treatments may vary depending on the stage of the cancer and whether your child has reached full growth. Chemotherapy uses drugs to kill cancer cells and shrink tumors. Radiation therapy involves high-dose X-rays or other high-energy rays to kill cancer cells and shrink tumors. Bone marrow transplantation is being tested in patient studies for those with advanced disease.

The prospect for curing children with stage I or II disease is about 90 percent, and more than 50 percent for those with widespread disease, even children with stage IV.

Chemotherapy

Chemotherapy uses drugs to kill cancer cells and shrink tumors. It may be taken orally or may be administered into a vein or muscle by needle. Chemotherapy is called a systemic treatment because the drugs enter the bloodstream and can kill cancer cells throughout the body. Chemotherapy also may be injected by needle into the fluid that surrounds the brain or back to treat certain types of lymphoma that spread to the brain.

Radiation Therapy

Radiation therapy, which uses X-rays at high doses in a very focused beam to kill malignant cells, is very effective in treating lymphomas. The side effects of this treatment vary depending upon which area of the body is being radiated.

Bone Marrow Transplant

Bone marrow transplant (BMT) is a newer treatment for lymphoma. Sometimes lymphoma cells become resistant to treatment with radiation therapy or chemotherapy. Very high doses of chemotherapy may then be used to treat the cancer. Because the high doses of chemotherapy can destroy bone marrow, marrow is taken from the bones before treatment. The marrow is then frozen and high-dose chemotherapy with or without radiation therapy is given to treat the cancer. The marrow that was removed is then thawed and returned by needle into a vein to replace the marrow destroyed by chemotherapy. This type of transplant is called an autologous transplant. If the marrow is from another person, the transplant is called an allogeneic transplant.