Understand Childhood Cancers and Blood Disorders
Bone tumors account for about five percent of the malignancies in children younger than 16 years old in the United States. They are the sixth most frequent tumor type in all children, but the third most common type in adolescents since they most commonly present during the second decade of life.
Osteosarcoma is the most common primary malignant tumor of bone and is diagnosed in about 400 children younger than 20 years old in the United States every year. Ewing's sarcoma is the second most common primary malignant tumor of bone. Other rare malignant tumors found in bone include: primary lymphoma of bone, malignant fibrous histiocytoma, and metastases of tumors from other sites (e.g. neuroblastoma). Benign tumors of bone include: eosinophilic granuloma and giant cell tumor.
In most patients we do not know why the cancer developed. Some people may have a rare condition that predisposes them to bone cancer. These include previous radiation therapy to a bone for another malignancy, the Li-Fraumeni syndrome, and retinoblastoma, a rare tumor of the eye. There are no known predisposing factors for Ewing's sarcoma.
Osteosarcoma and Ewing's sarcoma most often occur near the knee and present with pain. Sometimes there is a palpable mass if the tumor extends into the surrounding soft tissue. There may be associated fever, fatigue, and weight loss with Ewing's sarcoma. At times, the diagnosis of a malignant bone tumor is made after a fracture occurs in the affected bone and an x-ray shows a mass in addition to the fracture and an abnormal appearance of the bone.
Once a bone tumor is suspected from a regular x-ray, more sophisticated imaging studies, including MRI or CT scan of the affected bone is performed to obtain a more detailed image of the tumor and to plan a biopsy. Since different kinds of tumors originate in bone, a biopsy is essential for making a correct diagnosis. An ideal biopsy is an open biopsy performed by an experienced orthopedic oncologist. These specialists can plan the biopsy site in an area that will be resected later if the diagnosis is a malignant bone tumor.
Treatment for bone tumors depends upon the diagnosis. Benign tumors may require no treatment besides observation. Osteosarcoma treatment involves surgery and chemotherapy such as methotrexate, cisplatinum, and Adriamycin. Ewing's sarcoma is treated with different chemotherapy (ifosfamide, etoposide, vincristine, cyclophosphamide, and Adriamycin), and possibly radiation instead of surgery. Surgical removal of the tumor often occurs after a few courses of chemotherapy. The main reason for the delay in surgery is that chemotherapy may shrink the tumor and make removal of the tumor easier. This allows many patients to undergo limb-sparing procedures where the affected limb is not removed and may retain function. Chemotherapy is also important in treating metastatic disease. About 15-20 percent of patients have metastases to other organs (lungs, bone, and bone marrow) at diagnosis. A higher percentage of patients have micrometastatic disease at diagnosis that cannot be detected with CT scans or bone scans. Patients who present with no visible metastases and who undergo chemotherapy in addition to surgery (and/or radiation) have a very good long-term survival.
Brain tumors are the most common solid tumor of childhood. They are a heterogeneous group of disorders which usually present with persistent headache and vomiting but may sometimes develop a number of other symptoms such as eye problems, seizures, growth abnormalities or difficulty walking. An accurate diagnosis is critical to a successful outcome, as some brain tumors are malignant and others are benign. The type of brain tumor is usually identified by the initial tumor location and the microscopic appearance of the tumor tissue.
When a brain tumor is suspected in a child, a pediatric oncologist will review the clinical information with a pediatric neurologist and a neurosurgeon. Brain and spinal cord MRI and CT images are reviewed by a neuroradiologist to accurately assess the extent of the problem and to formulate a plan to deal with the tumor. The neurosurgeon will then either perform a surgical resection, if possible, or a biopsy if the tumor size and location make a complete removal difficult. This surgery should be performed by a neurosurgeon experienced in dealing with pediatric brain tumors and must be followed with specialized postoperative observation and treatment in an intensive care setting. After careful microscopic study of the tumor tissue samples by a neuropathologist, a diagnosis can be established. Additional laboratory studies on the tumor tissue are often performed to confirm the diagnosis and to better define the disease process. These additional studies may sometimes be performed at specialized pathology referral centers. Depending upon the results of the above studies, additional treatment is often required.
The outlook for cure depends on the microscopic appearance of the tumor tissue and the amount of disease that the neurosurgeons can safely resect. Radiation therapy is an important tool and is often used for toddlers, older children and adolescents to help control malignant disease. Radiotherapists have a variety of treatment options ranging from traditional x-ray therapy to newer techniques such as cyber knife and proton beam therapy. The latter is available at only three centers in the USA and patients from the New York metropolitan area are generally referred to Massachusetts General Hospital in Boston for this treatment.
Additional control of the disease may be achieved by the use of chemotherapy. Chemotherapy drugs which may be used for childhood brain tumors include Cyclophosphamide, Cisplatin, Carboplatinum, Etoposide, Vincristine, Temazolamide, Procarbazine and CCNU. Most of these are given intravenously through a central venous catheter. Children who receive these medications need to be closely monitored for possible adverse effects. Chemotherapy has begun to have a major impact in the outcomes of several pediatric brain cancers, including germ cell tumors and medulloblastomas.
A qualified pediatric oncologist should prescribe and supervise all chemotherapy administration and ensure that patients receive necessary supportive care measures. Careful follow-up observation and care are necessary. Continued long-term follow up of patients who have successfully completed treatment and are rendered disease free is necessary into adulthood, because of the risk of delayed complications that include effects on learning and growth.
Central Venous Access Devices
To effectively treat children with cancer, we need intravenous (IV) access to draw blood, infuse medications, fluids or blood products. Central venous access devices (CVAD) minimize the need for needle sticks, reducing the child's anxiety and discomfort while providing a safe, guaranteed route for administering irritating IV fluids and medications. There are many different types of CVADs. There are tunneled, external catheters (Broviac, Hickman, Groshong), peripherally inserted central catheters (PICC) and implanted venous catheters (Mediport, Port-a-Cath).
Broviacs, Hickmans and Groshong Catheters:
These flexible, external catheters are inserted under the skin into a major blood vessel and advanced until the tip almost reaches the right atrium of the heart. They are implanted under sterile conditions in the operating room. These catheters can have one, two, or even three separate tubes that can be used concurrently. The Broviac and Hickman catheters are flushed daily with a low concentration of heparin to prevent clotting. The Groshong does not require heparinization, only saline flushes. The external catheters do require home maintenance of daily flushing and every other day dressing changes. They also make it somewhat more difficult to bathe or swim. While requiring more maintenance, they are necessary for some kinds of cancer that require very intense therapy or stem cell transplant.
Peripherally Inserted Central Catheter (PICC)
The PICC is a flexible catheter that is usually inserted into an arm vein and advanced toward the right atrium of the heart. It does not require the operating room in order to place it; it can be done at the bedside.
Implanted Venous Access (Mediport, Port-a-Cath)
These catheters are surgically implanted under the skin and threaded into a major blood vessel and advanced until the tip almost reaches the right atrium of the heart. The port is usually placed in the subcutaneous tissue of the patient's upper chest or abdomen, and has a rubber-like surface to allow needle entry. A special needle (Huber needle) is required in order to access the port, without leaving a permanent hole in the surface. The advantage of these catheters is that there is no home maintenance required since they are completely under the skin. They are kept patent by flushing with a low concentration of heparin by the medical team, and when not in use, they only need to be flushed monthly. They present no problem with bathing or swimming.