Lymph nodes are small, grape-sized glands that exist throughout the body and make up part of the lymphatic fluid circulation system. Lymphatic fluid (or lymph) is a clear fluid that leaks out of blood vessels, and in order for the body to keep the blood volume constant, is collected and returned to the blood via the lymphatic circulation. Lymph nodes are connected to each other by lymph vessels that transfer the lymphatic fluid. Before returning the lymph to the blood, lymph nodes clean up the fluid, filter out infection-causing germs (bacteria, viruses, etc.). Most people can remember having swollen "glands" under their neck when they had an infection. Those "glands" were swollen lymph nodes that were reacting to the infection.
Clusters of lymph nodes exist in particular parts of the body, like the neck, the underarm, and the groin. There are also specific organs in the body that are considered part of the lymphatic system, like the spleen and the tonsils. These organs and the lymph nodes are the major regions of the body where lymphatic tissue is found, but small amounts of can also be found in many of the other organs in the body.
Hodgkin's disease is a disease of lymph nodes and lymphatic tissues, called a lymphoma. There are other types of lymphomas besides Hodgkin's disease, but they will be discussed in a separate review. Hodgkin's disease occurs when cells in the lymph nodes begin to grow out of control and compress nearby tissues, or spread throughout the body via the lymphatic circulation. Hodgkin's disease is distinguished from the other types of lymphomas by the way it looks under a microscope and by the way it grows and spreads.
Hodgkin's disease is an uncommon cancer in children. It is more common during adolescence than in early childhood. In fact, Hodgkin's disease is extremely rare in children under the age of 5 years.
No one knows what causes Hodgkin's disease. No clear-cut associations have been found with exposures to toxins, chemicals, or environmental agents. First-degree relatives of patients with Hodgkin's disease have a higher chance of developing the disease, but exactly how genetics control this disease is poorly understood.
Hodgkin’s is more common in people have underlying problems with their immune systems including certain viruses that affect the immune system, like HIV and EBV.
Because no one knows exactly what causes Hodgkin's disease, there are no specific steps to prevent developing it.
Hodgkin's disease is rare enough that it is not screened for with any specific tests. The best way to pick up a diagnosis of Hodgkin's disease early is to see a doctor regularly for a thorough physical examination.
Unfortunately, the early stages of Hodgkin's disease may not have any symptoms.
The most common presenting symptom is a swelling in the neck.
As the tumor grows in size, it can produce other symptoms including:
Many of these symptoms are non-specific, and could represent a variety of different conditions; however, a child with any of these symptoms should be seen by a physician.
When a patient presents with symptoms suggestive of Hodgkin's disease, his/her physician will perform a thorough history and physical examination. If there is a lymph node that is enlarged, it will likely be surgically removed with what is called an "excisional biopsy" so that it can be evaluated under a microscope. This is the only way Hodgkin’s can be diagnosed.
Other tests can help support the diagnosis and help to plan for treatment including blood tests and other imaging tests. A few different blood tests will probably be ordered. The physician will also get a CT scan and PET scan to stage the patient. Staging is important to guide the choice of treatment and offer information about prognosis. A simplified version of the staging system for Hodgkin's disease (called the Modified Ann Arbor Staging System) is offered below:
Stage 1. Single lymph node region involved with disease
Stage 2. Two or more lymph node regions involved on the same side of the diaphragm (the muscle that controls breathing and that separates the chest from the abdomen)
Stage 3. Lymph node regions involved on both sides of the diaphragm
Stage 4. Diffuse involvement of an organ that is not considered part of the lymphatic system (like the lung or liver).
If a patient has certain symptoms, this can affect the stage risk classification. High fevers, night sweats, or weight loss (greater than 10% of original body weight) are all called "B" symptoms. If a patient has B symptoms, then his/her stage will include the letter "B" after the stage number. If a patient doesn't have any of these B symptoms, then his/her stage will include the letter "A" after the stage number. Additionally, any disease that is found in regions other than lymph nodes (like other organs), is called extranodal disease. Any patient with extranodal disease will have the letter E included in their stage. Finally, patients with large (bulky) lymph nodes may have the letter X included in their stage. In addition, based on size and location of lymph nodes that are involved, patients will be classified as low, intermediate or high risk.
Over the years, the cure rates for pediatric Hodgkin's disease have increased dramatically. Given the excellent results achieved with older regimens, newer research efforts have focused on decreasing the toxicity of the available curative therapies in order to decrease long-term treatment-related side effects in survivors..
Chemotherapy is the use of anti-cancer drugs that go throughout the entire body. These drugs may be given through a vein as a liquid or by mouth as pills. Chemotherapy has become the mainstay of treatment for patients with Hodgkin's disease, and combinations of different chemotherapy drugs are used to kill the tumor cells.
There are many different chemotherapy regimens. Some of the more common pediatric regimens and the drugs used in them are listed below:
Pediatric Hodgkin's disease patients may be treated with radiation therapy after they receive chemotherapy. Many regimens use radiation therapy depending on the initial response to chemotherapy, so doctors will make a decision about using radiation after some treatment with chemotherapy is complete and they reassess the lymphoma with pictures again. Radiation therapy uses high-energy rays (similar to x-rays) from an external source to kill cancer cells.
Sometimes patients receive chemotherapy and radiation therapy and their Hodgkin's disease isn't cured. When this happens, further chemotherapy and radiation, or stem cell transplantation may be recommended. Stem cells are cells in everyone’s body that can develop into other types of cells when placed in certain environments. Stem cell transplantation is used along with high doses of chemotherapy. The high doses of chemotherapy are so intense that they destroy a patient's bone marrow. Without bone marrow, a person can't make the components of blood and the immune system that are necessary to survive. In order to replace the patient's bone marrow, stem cells are used. In the case of "autologous" stem cell transplants, a patient's own stem cells are harvested before the high dose chemotherapy is given, then stored, and finally returned to the patient after the chemotherapy is done. This way, the bone marrow can re-grow from the stem cells. This enables a patient to tolerate the super high doses of chemotherapy that work against Hodgkin's disease but have the unwanted side effect of wiping out healthy bone marrow. In allogeneic stem cell transplants, the stem cells of another person may be used to re-grow the bone marrow of a patient needing high-dose chemotherapy. Stem cell transplantation is a complex and intense treatment, so it is typically reserved for patients who aren't cured with the initial regimens of chemotherapy and radiation therapy.
Once a patient has been treated for Hodgkin's disease, he or she needs to be closely followed for a recurrence. At first, follow-up visits will occur fairly often. The longer a patient is free of disease, the less often he or she will have to go for checkups. Your doctor will tell you when he or she wants follow-up CT scans or PET scans. Unfortunately, anyone who receives radiation may be at higher risk for a second cancer later in life. This risk may be higher for children who receive radiation, and children who have had cancer treatment should be followed by a specialist who is able to screen for second cancers. The American Cancer Society and The Children’s Oncology Group has identified an increased risk of breast cancer in women who receive radiation to the chest as part of Hodgkin’s disease. For this reason, it is recommended that women who have had chest radiation in the past be screened for breast cancer with mammogram and MRI scans starting 8 years after their radiation treatment, or at age 30 (whichever is first).
Clinical trials are extremely important in furthering our knowledge of this disease. It is through clinical trials that we know what we do today, and many exciting new therapies are currently being tested. Talk to your doctor about participating in clinical trials in your area.
This article is meant to give you a better understanding of pediatric Hodgkin's disease. You may find this information useful when meeting with your physician, making treatment decisions, and continuing your search for information.