Wilms tumor and neuroblastoma are the most common abdominal tumors in children. Approximately 400 to 500 cases of each are diagnosed annually in the United States. Although both arise within the abdomen, the two tumors are quite different. In this article, I will discuss the symptoms of Wilms tumor and neuroblastoma, how the tumors are diagnosed, the child's prognosis, and the treatment of these tumors.
Clinical Picture of Wilms Tumor and Neuroblastoma
The following is a description of the signs and symptoms of Wilms tumor and neurblastoma.
Wilms tumor is a primary tumor of the kidney. The usual complaint is an abdominal mass felt by the parents or another family member. Children can also present with high blood pressure, blood in their urine, and constipation; however, these symptoms are uncommon. Once the pediatrician confirms the abdominal mass, a referral is made to a pediatric oncologist (a childhood cancer specialist). After the oncologist examines the child, special radiographs are ordered to determine where the location of the tumor and how far, if at all, the tumor spread. These studies include an abdominal ultrasound, a chest x-ray, and a CT (or CAT scan) of the chest, abdomen and pelvis. Once these studies are completed, a pediatric surgeon or pediatric urologist (pediatrician who specializes in childhood kidney, bladder, and genital diseases) and a pediatric radiation oncologist (specialist in administering radiation treatment) are consulted. If a Wilms tumor is suspected, a surgery is planned to examine and possibly remove the affected kidney.
Interestingly, there are rare diseases that predispose children to Wilms tumor. Examples include the Beckwith-Wiedemann syndrome, Denys-Drash syndrome, Perlman syndrome, hemihypertrophy, sporadic aniridia, and the WAGR syndrome. Because of their high-risk status, children with these rare diseases are usually advised to have repeat abdominal ultrasounds every three to four months to detect any tumors as early as possible.
Neuroblastomas arise from the sympathetic chain (a special group of nerves that run along side the entire spine) and adrenal gland. Therefore, a neuroblastoma can start anywhere along the spine or in the abdomen. It can cause various symptoms such as bumps on the head, bruises around the eyes (raccoon eyes), nasal congestion (of course, most cases of nasal congestion are due to a cold, not a tumor), proptosis (eyes bulging out), a neck mass, a chest mass, an abdominal mass, or constipation.
Neuroblastomas may also cause bone pain, inability to walk, and bone marrow failure, which can result in low blood counts and infection. The tumor may cause several symptoms due to indirect effects on the body. These can include profuse watery diarrhea, random and irregular movements of different muscles and/or eye changes, including a small pupil, an eyelid that droops on one side, or irregular movements of both eyes. There are cases of neuroblastoma than run in families. As well, children with certain rare conditions, known as Ondine curse and Hirschprung disease, can be predisposed to develop neuroblastoma. When the pediatrician suspects neuroblastoma, the child must be referred to a pediatric oncologist for the appropriate evaluation. The evaluation will include a medical and family history, physical examination, radiographic studies, blood and urine tests, and a bone marrow examination.
If there are signs of either tumor, the next step is to arrive at a medical diagnosis. The following passages describe how a diagnosis is reached for Wilms tumor and neuroblastoma.
The diagnosis of Wilms tumor is made after surgical removal of the kidney and surrounding lymph nodes (small glands found all over the body that are involved in the immune system). The pediatric pathologist (specialist in identifying tumors after looking at them under the microscope) must carefully examine the kidney for evidence of abnormal, cancerous appearing cells and the presence of tumor in lymph nodes. The extent of tumor spread (known as the stage) revealed by the radiographic studies and the appearance of the cancer cells under the microscope helps to determine the prognosis. Stage I tumors (best prognosis) are confined to the kidney, stage II tumors extend outside the kidney, stage III tumors have invaded the lymph nodes and stage IV tumors (worst prognosis) have spread to the lungs and/or other organs. Stage V tumors involve both kidneys. In this special case, each tumor is staged separately. For instance, the child may have a stage I tumor on the left and a stage II on the right. I will discuss the special surgical considerations for Wilms tumor that involves both kidneys under the treatment section.
The diagnosis of neuroblastoma is also made after examining tumor tissue after a surgical biopsy. The tumor tissue can originate from a lymph node, the bone marrow, the adrenal gland or any mass along the sympathetic chain. We also rely on a urine test to check for special chemicals known as catecholamines. These catecholamines are secreted by neuroblastoma cells and help the treating oncologist make a diagnosis and follow treatment response. The staging of neuroblastoma relies on the clinical and surgical assessment of the disease. Interestingly, infants can have a unique form of neuroblastoma that may undergo spontaneous regression.
A prognosis is a prediction of the probable course of a disease. The following passages describe how a prognosis is reached after a diagnosis of Wilms tumor or neuroblastoma.
The prognosis of Wilms tumor rests on the stage of the tumor and the presence of what is termed anaplasia (abnormal appearing cancer cells). Children with stage I tumors with or without anaplasia have a wonderful prognosis, whereas those with stage IV disease and anaplasia have the worst prognosis. Fortunately, most children have localized disease and have an excellent chance of cure.
The prognosis of neuroblastoma rests not only on disease stage, but also on the age of the child and on the biologic features of the tumor. As previously stated, some neuroblastomas can undergo spontaneous regression and others may only require surgical removal. However, children with either metastatic (the cancer has spread to other organs) neuroblastoma or a neuroblastoma with unfavorable biologic features (microscopic features such as DNA changes that are determined by special laboratory tests) have a poor prognosis even with aggressive chemotherapy. Several attempts have been made to measure urine catecholamines in infants to screen for neuroblastoma. To date, these screening efforts have met with limited success.
The treatment for Wilms tumor and neuroblastoma involves a multidisciplinary team approach including a pediatrician, pediatric oncologist, pediatric surgeon, pediatric pathologist and pediatric radiation oncologist. Each member of the team is critical and each component of therapy has improved the survival of children with these cancers. Following are specific therapies for each tumor.
The cornerstone of therapy for Wilms tumor is surgical removal of the affected kidney (called a nephrectomy) and multiple lymph nodes. In children with Wilms tumor affecting both kidneys, a kidney-sparing surgery is performed. In most cases, biopsies are done and chemotherapy is given to shrink the tumors. A second-look surgery is performed with removal of the most involved kidney and partial nephrectomy of the other. Surgery provides tissue to make a diagnosis and assess for lymph node metastases. In cases where only one kidney is involved, the unaffected kidney is always inspected for the presence of tumor. Children without evidence of metastases are treated with chemotherapy after the surgical procedure. Children with evidence of metastases (lung, lymph node, and brain) are advised to undergo radiation therapy in addition to chemotherapy. During and after therapy, a child’s progress is followed with repeated chest x-rays and abdominal ultrasounds to assess disease response and remission (temporary disappearance of the cancer) status. Moreover, monitoring for the harmful side effects of chemotherapy and radiation also requires repeat testing and examination.
The treatment of neuroblastoma depends on the child's age, tumor stage, and tumor biologic features. Some children with localized neuroblastoma are cured by surgery alone. However, children with metastatic disease still fare poorly despite surgery, chemotherapy, and radiation. In a recent study the addition of high-dose chemotherapy with bone marrow transplantation and medication called cis-retinoic acid (a vitamin A derivative) has improved the survival of children with metastatic disease. During and after therapy children undergo radiologic tests and bone marrow examinations to assess disease response and remission status.
Though rare, Wilms tumor and neuroblastoma are among the most common abdominal tumors in children. Although they are malignant tumors, most are curable using surgery with or without chemotherapy and/or radiation therapy. Scientific research has expanded our knowledge of the underlying genetic mutations that cause the transformation of normal cells into cancer cells. Despite our successes in pediatric oncology, there is room for much improvement in the treatment of children with stage IV Wilms tumor and neuroblastoma.
Our goal to cure all children with cancer will only be realized through the continuation of research and the participation of families in therapeutic studies.