Understand Childhood Cancers and Blood Disorders
Leukemia is a type of cancer that begins in the bone marrow, the area of the body where blood cells are produced. Leukemia derives its name from the Latin word for "white blood." In this disorder an abnormal, immature white cell develops, and instead of developing into a mature cell that helps protect the body from infections and foreign matter, it cannot do the normal job of a white cell and makes unlimited copies of itself. The result of this situation is that the bone marrow will be filled with these immature cells and the body will be unable to produce the normal red cells, white cells and platelets. This in turn can lead to anemia, with the patient looking pale and feeling tired, low platelet counts causing bruising and bleeding, and a decreased number of white cells, leading to fevers and infections.
There are several different types of leukemias which derive their name from the original malignant white cell. The most common type seen in children is called acute lymphoblastic leukemia, commonly known as ALL. The abnormal cell in this condition is a lymphoblast. There are a number of different subtypes that are determined by studies done on the surface proteins - these include pre-B-cell (the most common), B-cell (also known as Burkitt leukemia), and T-cell. Each of these behaves differently, has a different prognosis, and is treated differently. Acute nonlymphoblastic leukemia (also known as ANLL or AML) is also subdivided into different types depending on the cell of origin. Finally, chronic myelogenous leukemias are rarely seen in children, and will often present without the classic signs and symptoms of acute leukemia.
Aside from symptoms related to low blood counts, patients with leukemia may have a number of other presenting features that can be related to an abundance of the abnormal cells. Children may have enlarged, firm lymph nodes (also called swollen glands), most commonly in the neck. The liver and spleen may become enlarged, causing some belly discomfort or swelling. Some patients with an enlarged mass in the chest can have breathing difficulties. Involvement in the spinal fluid can cause neurologic symptoms, including headaches, vomiting, and vision problems. Finally, some children present with bone and joint pain, or even abnormal fractures.
A diagnosis of leukemia is suspected when children present with many of these signs and symptoms. The diagnosis is confirmed by examination of the bone marrow which is obtained by needle while the patient is sedated. A spinal tap is also necessary to determine if there is leukemia involving the spinal fluid that covers the brain and spinal cord; this also is done with a needle while the child is sedated.
The treatment for leukemia consists primarily of different strong medicine, commonly called chemotherapy. These drugs are given by vein (or central venous catheter), by muscle, by mouth, and in the spinal fluid by spinal tap. They are very effective in destroying the abnormal cells, allowing normal cells to proliferate once again and correct the original abnormalities. Some patients will require radiation therapy as well, particularly if there was involvement of leukemic cells in the spinal fluid. Finally, some patients will require stem cell transplant to offer them the best chance of a cure.
The outlook for children with leukemia has dramatically changed over the decades, with it evolving from an illness that was uniformly fatal to one where the majority of children are cured. The most dramatic results have been achieved in ALL, with a cure rate of about 85 percent. Even ANLL, a more difficult disease to treat, has now achieved a cure rate of about 55 percent. The major cause of failure to cure a patient is recurrence of their original disease, rather than a complication of the treatment. However, with the advent of new effective medications, better understanding of the biology of the disease, good supportive care, and newer techniques in determining miniscule numbers of persistent leukemic cells, it is hoped that the cure rate will continue to improve for these patients.
Lymphoma in Children
Lymphoma is a type of cancer that begins in the body's lymph nodes. Lymph nodes are part of the body's defense system, and will usually become activated when the body senses an infection or other foreign matter. The most common demonstration of this is seen with "swollen glands" in the neck when children have sore throats or ear infections. The typical response to the infection is enlargement of the nodes during the infection, with shrinkage of the lymph node when the infection has subsided.
The situation with lymphomas is different, as the nodes will appear and enlarge without any active infection. Usually, the nature of the lymph node is also different - in lymphomas the nodes will often be hard and immobile, and often appear in unusual areas, such as above the collar bone or in the armpits. They can present with symptoms such as fevers, weight loss, fatigue, and pain, but can often be without symptoms.
Lymphomas are divided into two broad groups, called Hodgkin's and Non-Hodgkin's lymphoma. This categorization is based on certain pathologic features seen under the microscope, but also exhibit different behavior patterns. The most common pattern of spread in Hodgkin's Disease (HD) is from lymph node to lymph node, with a smaller percentage of patients who have spread through the blood stream to distant sites, such as the lungs and liver. Most teenagers with HD will present with enlarged lymph nodes in the neck and chest; they often have no symptoms or complaints other than the neck mass. On other occasions, patients might have symptoms related to pressure on chest structures, with a persistent, worsening cough, shortness of breath, or swelling of the neck with a ruddy appearance. Finally, there are patients who present with symptoms that may include fevers, intense itching, weight loss, and drenching night sweats - these patients usually have more advanced disease that requires more intense treatment.
Patients with Non-Hodgkin's Lymphoma (NHL) have greater variability in how they present. There are several subtypes, including lymphoblastic, histiocytic, anaplastic, large cell, and Burkitt's, each with different behavior patterns and different sites of origin. Some types present with large masses in the chest that cause breathing problems, while others have large tumors in the belly that can cause pain, swelling, vomiting or jaundice. NHL can spread to the spinal fluid, causing a variety of neurologic complications, or to the bone marrow causing problems with blood counts. The behavior of the cancer can often be determined on the basis of the pathology, with different tumors being more aggressive and requiring more intense treatments.
Because of the different natures of the diseases, treatment for lymphomas varies greatly. Since HD spreads along the lymph system instead of the blood stream most of the time, treatments originally were heavily reliant on radiation therapy, with the radiation aimed at the tumor sites and adjacent areas. During the past several decades, with the advent of more effective chemotherapy regimens, nearly all patients are treated with short courses of chemotherapy, and low dose or no radiation therapy. This has eliminated the need for a major surgical procedure, called a staging laparotomy, that used to be necessary for patients treated with radiation alone. Many chemotherapy drugs have been shown to be very active against Hodgkin's Disease, and many combinations of these drugs are currently in use. The intensity of the regimens depends on the staging (the extent of spread) at diagnosis, the subtype of HD, and the rapidity of response to initial therapy.
The treatments for NHL are dictated primarily by the pathologic subtype, and to some degree, the extent of disease spread. Patients with Burkitt's Lymphoma as a rule are treated with very intense chemotherapy courses, but for a relatively short period of time, with all treatment completed within a few months. On the other extreme, children with Lymphoblastic Lymphoma are treated intensively for several months, followed by maintenance therapy that continues for a few years. Some children with lymphoma of the skin can be treated with surgical excision only, with close observation following the surgery. Radiation is rarely indicated these days, and is usually reserved for emergency treatment of compression of the airway or spinal cord, or involvement of the spinal fluid.
Treatment results have improved dramatically for nearly all types of lymphoma. The overall cure rate for HD is in the vicinity of 90-95 percent, with the lymphocyte predominant subtype nearly 100 percent. Likewise, cure rates for NHL have risen to better than 85 percent with the advent of better treatment regimens and improved supportive care. Exciting developments include the development of "designer drugs," newer drugs that target very specific portions of the malignant cell; these have already been introduced in the treatment of B-cell and T-cell lymphoma.
As the cure rate for lymphomas has improved and there has been better understanding of the biology of the cells and prognostic features, there has been interest in decreasing treatment for those who might require far less treatment for the same good outcome. This has been particularly important to minimize potential long term complications of treatment. The impact of this is being seen with HD, which used to have a significant risk of long term complications, including second cancers, now reduced with the elimination of certain medications and reduction or elimination of radiation therapy.
Neuroblastoma is a tumor that arises in the adrenal gland or in nerve cells next to the spine. There are about 600 new cases of neuroblastoma diagnosed in children every year in the United States which accounts for approximately 8% of all childhood cancers. It is the most common cancer found in infants less than 1 year old.
Many children will present with an abdominal mass as the first symptom, especially if the tumor is in the adrenal gland. Tumors that occur along the spine may grow into the spinal canal and cause spinal cord compression. This may produce symptoms of pain, weakness in the legs, and/or incontinence of urine and/or stool. Many neuroblastomas metastasize to other organs such as the bone marrow, bone, lymph nodes, liver, and orbits. Orbital involvement may give the appearance of "raccoon eyes" where there is a bluish discoloration of the skin around the eyes. Other possible symptoms of neuroblastomas include: random jerking eye movements, diarrhea, bone pain, irritability, sweating, and high blood pressure.
Diagnosis is usually made by obtaining a biopsy of the tumor. The biopsy specimen will have a characteristic appearance when observed under the microscope. In addition, a biopsy specimen can be used to obtain other prognostic information. Genetic tests that reveal particular features, such as extra copies of the N-myc gene, loss of chromosome 1p, and gain at chromosome 17q predict a poorer prognosis.
In some cases, the diagnosis can be made based on samples of urine and bone marrow. Neuroblastomas produce substances such as VMA and HVA that are released into the bloodstream and then are excreted into the urine. Increased levels of VMA and HVA suggest the presence of neuroblastoma. If these levels are elevated at diagnosis, then they can be followed over the course of treatment and should decrease as the tumor disappears. Bone marrow samples may show the presence of neuroblastoma cells if the neuroblastoma has metastasized. The combination of elevated urine VMA and HVA and tumor cells in the bone marrow can substitute for a biopsy specimen in confirming the diagnosis of neuroblastoma.
Treatment for neuroblastoma is based on the results of the biopsy and the metastatic workup. Metastases can be detected with a bone scan and a CT scan of the chest, abdomen, and pelvis, and a neuroblastoma-specific nuclear medicine test, an MIBG scan. For localized tumors, surgery and observation is often all that is needed. Infants less than 1 year old (and possibly up to 18 months old) with metastatic disease limited to the skin, liver, and/or bone marrow can also be observed without chemotherapy because neuroblastoma can spontaneously regress over time. If children with localized tumors or infants with limited metastatic disease have severe symptoms such as spinal cord compression or difficulty breathing, they may need chemotherapy and/or radiation therapy to help speed up the disappearance of the tumor in order to alleviate the symptoms. Children with non-localized disease and with poor genetic prognostic factors require a combination of surgery, chemotherapy, radiation therapy and, most of the time, stem cell transplant.