• Wilms Tumor

    Wilms tumor (also called nephroblastoma) is a cancerous tumor in the cells of the kidney. Fortunately, with the right treatment, Wilms tumor is highly treatable.

    • Wilms tumor is the most common type of renal (kidney) cancer in children, accounting for about 6 percent of all childhood cancers.
    • About 500 children in the United States are diagnosed with a Wilms tumor each year.
    • Wilms tumor can occur at any age between infancy and age 15, but is most common in children age 5 or younger. Adults rarely have Wilms tumor.
    • The tumor can spread outside the kidney, most often to the abdominal lymph nodes and lungs.
    • With prompt and aggressive treatment, Wilms tumor is successfully treated in the majority of children. Multidisciplinary approaches, including a combination of surgery, and/or chemotherapy and/or radiation therapy can be used.

    Wilms Tumor Treatment – and Specialized Expertise in Bilateral Tumors – at Dana-Farber/Boston Children’s

    Children with Wilms Tumor receive highly coordinated multidisciplinary care through the Kidney Tumor Program at Dana-Farber/Boston Children’s.

    As a regional, national and international referral center, our surgeons and solid tumor oncologists have extensive expertise in the care of children with Wilms tumor, particularly those with bilateral tumors (tumors on both sides of the abdomen), large tumors, or "unfavorable" tumor subtypes rarely seen elsewhere. Our multidisciplinary team, which draws on specialists from across Dana-Farber Cancer Institute and Boston Children's Hospital, works together to develop thoughtful and precise treatment plans.

    Wilms tumor specialists at Dana-Farber/Boston Children’s have pioneered important new surgical and medical approaches to the treatment of Wilms. They also play key roles in large cooperative studies through the National Wilms Tumor Study Group and Children's Oncology Group. These studies have rigorously compared treatment plans to determine the most effective and safest treatments and have helped to greatly advance Wilms tumor treatment over the last three decades.

    What is the cause of Wilms tumor?

    Most cases of Wilms tumor occur with no family history of the disease or other known cause. In a small number of cases, children are born with a genetic predisposition to develop Wilms Tumor. These children have rare genetic syndromes such as:

    • Hemihypertrophy (one side of the body larger than the other)
    • WAGR syndrome (Wilms, aniridia, genitourinary abnormalities)
    • Denys-Drash syndrome (a syndrome of renal failure, hypertension and genital abnormalities)
    • Beckwith-Wiedemann syndrome (an “overgrowth” syndrome)

    What are the symptoms of Wilms tumor?

    The most common symptom of Wilms tumor is the sudden appearance of a solid mass in the abdomen. Though each child may experience symptoms differently, other symptoms may include:

    • swelling of the abdomen
    • blood in the urine
    • abdominal pain
    • decreased appetite
    • weakness or tiredness
    • fever
    • high blood pressure
    • constipation

    Keep in mind that the symptoms of Wilms tumor may resemble other more common conditions or medical problems. Always consult your child's physician for help with getting to a diagnosis.

    How is Wilms tumor diagnosed in children?

    The first step in treating your child is forming an accurate and complete diagnosis. Your child’s physician may recommend a number of different tests to determine the cause of the symptoms. In addition to a complete medical history and physical examination, your child’s doctor may order one or more of the following:

    • Abdominal ultrasound: This imaging test can provide an outline of your child’s kidneys and the tumor, and determine if there are problems in the renal vein or other major veins in the abdomen. It can also determine if there are tumors in the opposite kidney. This is usually the first test we recommend if a tumor is suspected.
    • Chest or abdominal x-ray: An x-ray can help determine the size and location of the tumor and whether it has spread.
    • Computed tomography (CT): A CT scan of the abdomen and chest can provide more detailed images than x-rays and are the preferred method for determining whether a Wilms tumor has spread to the lungs and to assess whether a tumor can be surgically removed safely.
    • Magnetic resonance imaging (MRI): An MRI of the abdomen may be used in some cases to look for tumor in blood vessels or other organs. MRI is the preferred imaging method for children with bilateral renal tumors, particularly when multiple imaging studies will be required.
    • Blood and urine tests: These can evaluate your child’s kidney and liver function and look for any other blood-related abnormalities.
    • Biopsy: In some cases, the team will decide to do a biopsy to help determine the tumor type. This may be appropriate if the tumor is very large and cannot be safely removed, or if there is evidence of bilateral tumors or extensive tumor spread.
    • Surgery to remove the tumor and kidney (nephrectomy). Surgery is a critical component of Wilms tumor diagnosis and treatment.

    After we complete all necessary tests, our experts meet to review and discuss what they have learned about your child's condition. Then we will meet with you and your family to discuss the results and outline the best treatment options.

    How is Wilms tumor classified?

    An important part of diagnosing Wilms tumor involves staging and classifying the disease, which will help your child’s doctor determine treatment options and prognosis. Staging is the process of determining whether the cancer has spread and, if so, how far.

    Kidney tumors are typically categorized into five stages. Wilms tumor is staged as follows according to guidelines from the Children’s Oncology Group (COG), a national consortium of pediatric cancer centers:

    • Stage I: The tumor is limited to the kidney and can be completely removed surgically. About 20 percent of tumors are stage I.
    • Stage II: The tumor extends beyond the kidney but can be completely removed surgically. This includes about 22 percent of tumors.
    • Stage III: The tumor cannot be completely removed surgically or is spilled at surgery, but disease is still limited to the abdomen. About 32 percent of tumors are stage three.
    • Stage IV: The disease has spread from the abdomen through the bloodstream and may be found in other parts of the body, most often the lung or liver. About 20 percent of cases are stage IV.
    • Stage V: The tumor is found on both kidneys (bilateral tumor) at the time of diagnosis. This occurs in about 6 percent of cases.

    Your child’s doctor can provide additional information on the classification of Wilms tumors.

    What is the treatment for Wilms tumor?

    Your child’s physician will determine a specific course of treatment based on several factors, including:

    • your child's age, overall health and medical history
    • type, location, and size of the tumor
    • extent of the disease (stage)
    • your child's tolerance for specific medications, procedures or therapies
    • how your child's doctors expect the disease to progress
    • genetic characteristics of the tumor

    The first step in most treatments is surgery to remove the tumor. The most common operation is a radical nephrectomy, which removes the whole kidney, the tissue around the kidney, the ureter (the tube that drains urine from the kidney to the bladder) and the adrenal gland (which sits on top of the kidney). This operation is performed if the tumor has occurred in only one kidney. Some cases of low-stage Wilms tumor can be treated with surgery alone.

    If your child has tumors in both kidneys or has a known predisposition to kidney cancer, your child’s physician may recommend a partial nephrectomy or kidney-sparing surgery which aims to remove the tumor while leaving the maximum amount of healthy kidney tissue.

    In rare cases—when the tumor is very large—your child’s doctor may recommend chemotherapy to try to shrink the tumor before surgery. In some cases, a biopsy may be the best first surgical procedure for your child, to establish the diagnosis before treatment.

    Surgical procedures for Wilms tumor – especially bilateral tumors – should be performed in specialized centers where experienced surgeons, working in the most technologically advanced settings, can provide the most appropriate kidney surgery. Surgeons at Dana-Farber/Boston Children’s have extensive, specialized experience in treating Wilms tumor.

    Surgery is usually followed by chemotherapy and sometimes radiation therapy. The type of chemotherapy and need for radiation are determined by tumor stage (extent of spread of the tumor) and tumor type. Radiation therapy may be indicated for some tumors, including any that have spread to the lymph nodes in the abdomen or the lungs.

    In very rare cases, a stem cell transplant, involving a transplant of your child’s own stem cells, may be used. This allows your child’s physician to give high-intensity chemotherapy in difficult to treat cases of Wilms tumor. Stem cell transplantation and the treatment needed to manage its effects are complex and involve some risk. Your physician will give you more detailed information on what to expect.

    Treating other kidney tumors
    Malignant rhabdoid tumor of the kidney was once considered a subset of Wilms tumor, but is now classified as a separate tumor type in its own right. Other types of kidney tumors include renal cell carcinoma, clear cell sarcoma of the kidney, cystic nephroma and congenital mesoblastic nephroma.

    How are side effects of Wilms tumor treatment managed?

    Side effects in the treatment of Wilms tumor can arise from surgery, radiation or chemotherapy.

    Our goal is to keep your child as healthy and strong as possible throughout treatment. Some side effects can be managed with standard medical approaches. However, Dana-Farber/Boston Children’s also has specialists who deliver complementary or alternative medicines. These treatments, which may help control pain and side effects of therapy, include the following:

    • acupuncture/acupressure
    • therapeutic touch
    • massage
    • herbs
    • dietary recommendations

    We also have nutritionists who can help manage nausea or other side effects, child life specialists who offer play therapy, psychosocial oncologists and social workers who give psychosocial support, and many other support specialists to help with all aspects of cancer treatment.

    What is the latest Wilms tumor research?

    Researchers at the Dana-Farber/Boston Children’s Kidney Tumor Program conduct laboratory and clinical research designed to improve understanding and treatment of pediatric kidney tumors. We also offer clinical trials through the Children’s Oncology Group (COG), and three of our specialists – Robert Shamberger, MD; Elizabeth Mullen, MD, FAAP; and Tom Hamilton, MD; are on the COG renal tumor committee.

    Here are some of our latest research studies:

    • Identifying the best treatment for Wilms tumor: Major advancements have occurred in treatment of Wilms tumor over the last three decades, primarily because of studies by the National Wilms Tumor Study Group and Children's Oncology Group, in which Dana-Farber/Boston Children’s physicians have played key roles. These studies have rigorously compared treatment regimens (treatment plans), and helped define the optimal treatment for each stage and type of Wilms tumor. In one large study, it was shown for low-stage Wilms tumor that briefer courses of therapy were safer and as effective as longer courses. A recent COG study initiated by Dana Farber/Boston Children’s doctors, including Robert Shamberger, MD, and Elizabeth Mullen, MD, FAAP, demonstrated that young children (less than two years of age) with small tumors can be treated safely with surgery only, without the need for chemotherapy or radiation. This study also offered adjustments of therapy for children with Stage I, II and III tumors based on specific genetic findings. This study is the first study in childhood renal tumors to base therapy on the biology of the individual child’s tumor. Elizabeth Mullen, MD, FAAP, is the vice-chair of this study. 
    • Renal tumor biology and risk stratification: Elizabeth Mullen, MD, FAAP, is the Protocol Chair for the COG Renal Tumor Biology and Risk Stratification Protocol (AREN03B2). This has been open since 2006, remains open to accrual, and currently has enrolled over 4,800 patients. This study involves real-time, coordinated review of Wilms tumor diagnoses by multiple specialists to determine the most accurate staging and risk stratification. Through this study, researchers have learned that many cases of Wilms tumor are initially misdiagnosed or not accurately staged. Through accurate diagnosis and staging, however, children can receive the best possible treatment regimen.
    • Risk-stratifying treatment of children with bilateral tumors: The traditional treatment for pediatric kidney tumors is a two-step process: Surgeons remove as much of the tumor as possible, then oncologists use chemotherapy to kill remaining cancerous cells. If the tumor is bilateral (appearing in both kidneys), chemotherapy is sometimes also used before surgery to reduce the size of the tumor so as to save the maximum amount of healthy kidney tissue. Our researchers are investigating the use of continuous pathological review throughout treatment to evaluate the best therapeutic approach for bilateral pediatric kidney tumors.
    • Searching for markers: Researchers are conducting studies to better understand how to diagnose and treat renal tumors. For example, our researchers are investigating whether kidney tumors emit markers in a child’s urine. If discovered, these markers could be used to screen for early recurrence of relapsed cancers. They may also help clinicians screen types of tumors up front, so treatments are personalized to the exact make-up of a child’s tumor. Dana-Farber/Boston Children’s is also involved in one of the country’s most comprehensive precision cancer medicine initiatives, called Profile. Ultimately, this important research project will result in a database of genetic changes in all types of cancer, including Wilms tumor. This research is advancing scientists’ understanding of the genetic causes of cancer, and how that information may ultimately lead to improved treatment.

    Clinical trials

    For many children with rare or hard-to-treat conditions, clinical trials provide new options.

    What is the long-term outlook for children with Wilms tumor?

    As with any cancer, prognosis and long-term survival can vary greatly from child to child depending primarily on the stage of the disease and the tumor cells' appearance under a microscope. Prompt medical attention, aggressive therapy and continued follow-up care are important for the best possible prognosis.

    With prompt, aggressive treatment, most children with Wilms tumor are successfully treated and experience relatively few side effects. More aggressive tumors that have spread significantly may be harder to cure. Should a tumor come back after treatment, your doctor may recommend additional surgery, chemotherapy and/or radiation therapy.

    The goal of treatment is both to cure the cancer and minimize the long-term effects of therapy. Children, however, are at some risk of late-effects of the cancer and its treatment, including high blood pressure, heart and lung problems after chemotherapy or radiation therapy, and slowed or decreased growth and development. Reduced kidney function may appear primarily in children with tumors in both kidneys (bilateral involvement), or with a predisposition syndrome that causes kidney abnormalities (nephritis) distinct from those related to the tumor or treatment.

    Factors that influence the outlook for a child with Wilms tumor include:

    • extent of the disease
    • the histology of the tumor (what it looks like under the microscope)
    • genetic changes in the tumor
    • age and overall health of the child at diagnosis
    • size of the primary tumor
    • response to therapy
    • your child's tolerance of specific medications, procedures or therapies
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