A-Z Core Disease & Treatment Terms

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Abdominal Mass

An abdominal mass is one of the most common and recognizable signs of Wilms tumor. Parents often notice a firm lump or swelling in a child's abdomen during bathing, dressing, or routine activities. The mass is usually painless and may continue to grow as the tumor enlarges. Because Wilms tumor develops in the kidney, an abdominal mass is frequently the first symptom that leads to medical investigation. Any unexplained abdominal lump in a child should be assessed promptly by a healthcare professional to determine the underlying cause and initiate appropriate testing.

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Abdominal Ultrasound

An abdominal ultrasound is typically the first imaging test used when Wilms tumor is suspected. The procedure uses sound waves to create detailed images of the kidneys and surrounding organs without exposing the child to radiation. Ultrasound can help identify the presence, size, and location of a kidney tumor and may also reveal abnormalities in nearby structures. Because it is safe, painless, and widely available, abdominal ultrasound plays a critical role in the early diagnosis of childhood kidney cancer and often serves as the first step in the diagnostic process.

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Anaplasia

Anaplasia refers to abnormal cancer cells that appear more aggressive when examined under a microscope. In Wilms tumor, the presence of anaplasia is an important pathological finding because it can influence treatment decisions and prognosis. Tumors containing anaplastic cells may be less responsive to standard therapies and often require more intensive treatment approaches. Pathologists carefully assess tumor tissue for evidence of focal or diffuse anaplasia to help classify risk and guide the overall treatment strategy.

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Anemia

Anemia is a condition in which the body has fewer healthy red blood cells than normal. Children with Wilms tumor may develop anemia due to the cancer itself, blood loss, reduced red blood cell production, or treatment-related side effects. Common symptoms include fatigue, weakness, pale skin, dizziness, and reduced energy levels. Blood tests performed during diagnosis and treatment help monitor anemia and determine whether supportive interventions such as iron supplementation or blood transfusions may be required.

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Bilateral Wilms Tumor

Bilateral Wilms tumor occurs when tumors develop in both kidneys either at the same time or within a short period of each other. This form of childhood kidney cancer is less common than unilateral disease and presents unique treatment challenges because preserving kidney function becomes a major priority. Treatment often includes chemotherapy before surgery to shrink tumors and increase the likelihood of nephron-sparing surgery. Careful long-term monitoring is essential because children with bilateral Wilms tumor may face a higher risk of future kidney complications.

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Biopsy

A biopsy is a medical procedure used to remove a small sample of tissue for microscopic examination. In some cases of Wilms tumor, a biopsy may be performed to confirm the diagnosis and determine the tumor's histological characteristics. The tissue sample allows pathologists to evaluate the cancer cells, identify features such as anaplasia, and help guide treatment planning. The decision to perform a biopsy varies according to treatment protocols used by different pediatric oncology groups around the world.

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Blastema

Blastema refers to immature kidney cells that are commonly found within Wilms tumors. These primitive cells resemble those present during normal kidney development before birth. Pathologists assess the amount and characteristics of blastemal tissue because it can provide valuable information about tumor biology, treatment response, and prognosis. In some high-risk forms of Wilms tumor, blastemal cells remain prominent after chemotherapy, which may indicate a need for more intensive treatment.

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Blood Pressure

Blood pressure measures the force of blood flowing through the arteries. Children with Wilms tumor may develop high blood pressure, known as hypertension, because the tumor can affect normal kidney function and hormone regulation. Monitoring blood pressure is an important part of both diagnosis and ongoing care. Elevated blood pressure may improve following treatment, but some survivors require long-term monitoring to detect and manage kidney-related cardiovascular complications.

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CBC (Complete Blood Count)

A Complete Blood Count (CBC) is one of the most commonly performed blood tests in pediatric oncology. The test measures red blood cells, white blood cells, and platelets, providing valuable information about a child's overall health and bone marrow function. CBC testing helps identify anemia, infection risk, and treatment-related complications throughout the cancer journey. Regular monitoring allows healthcare teams to adjust treatment plans and provide supportive care when necessary.

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Chemotherapy

Chemotherapy is a cornerstone of Wilms tumor treatment and involves the use of anti-cancer drugs to destroy cancer cells. Depending on the stage, histology, and treatment protocol, chemotherapy may be given before surgery, after surgery, or both. Common chemotherapy drugs used in Wilms tumor include vincristine, dactinomycin, and doxorubicin. Chemotherapy plays a critical role in reducing tumor size, eliminating microscopic disease, lowering the risk of relapse, and improving long-term survival outcomes.

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Chest CT Scan

A Chest CT Scan is an advanced imaging test used to determine whether Wilms tumor has spread to the lungs. Since the lungs are the most common site of metastatic disease in Wilms tumor, chest imaging is a key component of staging. CT scans provide highly detailed images that can detect small metastatic nodules that may not be visible on standard chest X-rays. The results help guide treatment intensity and determine whether additional therapies such as radiation may be required.

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Childhood Kidney Cancer

Childhood kidney cancer refers to cancers that develop in the kidneys during childhood, with Wilms tumor accounting for the vast majority of cases. Although relatively rare compared with adult cancers, childhood kidney cancer is one of the most common pediatric solid tumors. Advances in diagnosis, surgery, chemotherapy, radiation therapy, and supportive care have significantly improved survival rates. Early detection and access to specialized pediatric oncology care remain important factors in achieving the best possible outcomes.

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CT Scan

A CT Scan (Computed Tomography Scan) is a specialized imaging test that uses X-rays and computer technology to produce detailed cross-sectional images of the body. CT scans are commonly used in Wilms tumor diagnosis, staging, and treatment planning. They help evaluate tumor size, location, spread to nearby structures, and possible metastatic disease. CT imaging provides critical information that assists surgeons, oncologists, and radiologists in developing an individualized treatment strategy.

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Dactinomycin

Dactinomycin, also known as Actinomycin D, is one of the primary chemotherapy drugs used to treat Wilms tumor. It is frequently combined with vincristine and other agents as part of established treatment protocols. Dactinomycin works by interfering with cancer cell growth and preventing tumor cells from reproducing. The drug has contributed significantly to the improved survival rates achieved in children with favorable histology Wilms tumor over the past several decades.

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Diagnosis

The diagnosis of Wilms tumor involves a combination of clinical assessment, imaging studies, laboratory testing, and pathological evaluation. Doctors typically begin by reviewing symptoms and performing a physical examination before ordering imaging tests such as ultrasound, CT scans, or MRI scans. Additional tests help determine the stage of disease and whether the cancer has spread. Accurate diagnosis is essential because treatment recommendations depend on tumor characteristics, stage, histology, and overall patient health.

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Diffuse Anaplasia

Diffuse anaplasia is a high-risk pathological feature found in some Wilms tumors. Unlike focal anaplasia, which is limited to specific areas of the tumor, diffuse anaplasia is more widespread and generally associated with a less favorable prognosis. Children with diffuse anaplastic Wilms tumor often require more intensive chemotherapy and additional treatment approaches. Identifying diffuse anaplasia is therefore a critical part of risk stratification and treatment planning.

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Doxorubicin

Doxorubicin is a powerful chemotherapy drug commonly used in higher-stage or higher-risk Wilms tumor treatment protocols. It belongs to a group of medications known as anthracyclines and works by damaging cancer cell DNA. Doxorubicin has contributed substantially to improved survival outcomes but requires careful monitoring because it can affect heart function. Long-term follow-up care often includes cardiac assessments for children who received anthracycline-based treatment.

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Favorable Histology

Favorable histology describes the most common form of Wilms tumor and is associated with excellent treatment outcomes. Under the microscope, favorable histology tumors lack the aggressive cellular features seen in anaplastic disease. Children with favorable histology Wilms tumor generally respond very well to standard treatment protocols, and long-term survival rates are high. Histological classification is one of the most important factors used to guide treatment decisions.

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Hematuria

Hematuria is the medical term for blood in the urine. Although not present in every child with Wilms tumor, hematuria can be an important warning sign that prompts medical evaluation. The blood may be visible to the naked eye or detected through laboratory testing. Because hematuria can also result from infections, kidney stones, or other conditions, further investigation is usually required to identify the underlying cause.

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Histology

Histology refers to the microscopic examination of tissue samples to determine the characteristics of a tumor. In Wilms tumor, histological analysis helps classify the cancer, assess treatment response, identify anaplasia, and determine overall risk. Histology is one of the most important factors influencing treatment recommendations and prognosis. Pathology reports often provide detailed information about the cellular composition and biological behavior of the tumor.

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Hypertension

Hypertension, or high blood pressure, is a common symptom associated with Wilms tumor because the kidneys play a central role in regulating blood pressure. The presence of a kidney tumor can disrupt this process and lead to elevated blood pressure levels. Hypertension may improve after successful treatment but can also remain a long-term health concern for some survivors. Regular monitoring is therefore an important component of follow-up care.

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MRI (Magnetic Resonance Imaging)

Magnetic Resonance Imaging (MRI) is an advanced imaging technique that uses powerful magnets and radio waves to create detailed images of internal organs and tissues. MRI is particularly useful for evaluating tumor extent, blood vessel involvement, and complex anatomical structures. Unlike CT scans, MRI does not use ionizing radiation, making it an important diagnostic tool in pediatric oncology. MRI findings help support accurate staging and treatment planning.

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Metastasis

Metastasis occurs when cancer cells spread from the original tumor site to other parts of the body. In Wilms tumor, the lungs are the most common site of metastatic disease, although the liver, bones, and brain can also be affected in rare cases. The presence of metastasis is an important factor in determining the stage of disease and influences treatment planning. While metastatic Wilms tumor is considered more advanced, modern treatment approaches combining chemotherapy, surgery, and radiation therapy have significantly improved survival outcomes for many children diagnosed with stage 4 disease.

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Multidisciplinary Team (MDT)

A Multidisciplinary Team (MDT) is a group of healthcare professionals who work together to plan and deliver care for children with Wilms tumor. The team may include pediatric oncologists, surgeons, radiologists, pathologists, radiation oncologists, nephrologists, nurses, psychologists, social workers, and other specialists. By bringing together expertise from multiple disciplines, MDTs help ensure that treatment decisions are comprehensive, evidence-based, and tailored to the individual needs of the child and family throughout the cancer journey.

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Neoadjuvant Chemotherapy

Neoadjuvant chemotherapy refers to chemotherapy given before surgery to shrink a tumor and improve the likelihood of successful surgical removal. This approach is commonly used within treatment protocols developed by the International Society of Paediatric Oncology (SIOP). By reducing tumor size before surgery, neoadjuvant chemotherapy can lower the risk of tumor rupture, preserve healthy kidney tissue, and improve surgical outcomes. Treatment plans are individualized based on tumor characteristics, stage, and clinical presentation.

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Nephrectomy

A nephrectomy is a surgical procedure that removes all or part of a kidney affected by Wilms tumor. It remains one of the most important treatments for childhood kidney cancer and is often performed alongside chemotherapy and other therapies. The procedure allows surgeons to remove the tumor, evaluate nearby tissues, and provide critical pathological information used for staging and treatment planning. Long-term follow-up is essential because children who undergo nephrectomy require ongoing monitoring of kidney function, blood pressure, and overall renal health.

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Nephroblastoma

Nephroblastoma is the medical term for Wilms tumor, the most common kidney cancer affecting children. The disease develops from immature kidney cells that fail to mature normally during fetal development. Although nephroblastoma is considered a rare childhood cancer, it accounts for the majority of pediatric kidney tumors worldwide. Advances in diagnosis, surgery, chemotherapy, and supportive care have resulted in excellent survival rates for many children, particularly those diagnosed with favorable histology disease.

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Nephrogenic Rest

A nephrogenic rest is an area of abnormal kidney tissue that remains after birth and may be associated with an increased risk of developing Wilms tumor. These clusters of immature cells are considered precursor lesions and are sometimes identified in children with bilateral Wilms tumor or certain genetic syndromes. The presence of nephrogenic rests can influence treatment planning and long-term surveillance strategies. Ongoing monitoring may be recommended for children at increased risk of developing additional kidney tumors.

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Oncologist

An oncologist is a physician who specializes in the diagnosis, treatment, and management of cancer. In the context of Wilms tumor, pediatric oncologists coordinate treatment plans that may include chemotherapy, surgery, radiation therapy, and survivorship care. They also monitor treatment response, manage side effects, and oversee long-term follow-up. Pediatric oncologists play a central role in helping children and families navigate the challenges associated with childhood cancer treatment.

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Overall Survival (OS)

Overall Survival (OS) is a commonly used measure in childhood cancer research and refers to the percentage of patients who remain alive after a specific period of time following diagnosis. Overall survival rates help researchers, clinicians, and families understand treatment outcomes and compare the effectiveness of different therapies. For favorable histology Wilms tumor, overall survival rates often exceed 90% in high-income countries, reflecting significant advances in pediatric oncology care.

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Pathologist

A pathologist is a doctor who examines tissue samples, cells, and laboratory specimens to diagnose disease. In Wilms tumor, pathologists play a critical role by confirming the diagnosis, identifying histological features, assessing treatment response, and determining whether anaplasia is present. Their findings help establish risk classification and guide treatment planning. Accurate pathology review is essential for ensuring that children receive the most appropriate therapy for their specific type of disease.

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Pediatric Oncologist

A pediatric oncologist is a medical specialist dedicated to the treatment of cancers affecting children and adolescents. These physicians have extensive expertise in childhood cancers such as Wilms tumor and work closely with multidisciplinary teams to develop individualized treatment plans. Pediatric oncologists oversee chemotherapy administration, monitor treatment response, manage complications, and coordinate survivorship care. Their specialized knowledge is essential for achieving the best possible outcomes for children with cancer.

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Pulmonary Metastases

Pulmonary metastases occur when Wilms tumor spreads from the kidney to the lungs. The lungs are the most common site of metastatic disease in children diagnosed with stage 4 Wilms tumor. Pulmonary metastases may be detected through chest CT scans or other imaging studies performed during staging. Treatment often includes chemotherapy and, in some cases, surgery or radiation therapy. Advances in treatment protocols have greatly improved outcomes for children with lung involvement.

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Radiation Oncology

Radiation oncology is the medical specialty responsible for planning and delivering radiation therapy to treat cancer. Radiation oncologists work closely with pediatric oncology teams to determine when radiation is appropriate and how it should be administered. In Wilms tumor, radiation therapy may be used for advanced-stage disease, metastatic disease, or tumors with specific high-risk features. Careful planning helps maximize treatment effectiveness while minimizing exposure to healthy tissues.

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Radiation Therapy

Radiation therapy uses high-energy radiation to destroy cancer cells and reduce the risk of recurrence. Although not required for every child with Wilms tumor, radiation therapy can play an important role in the treatment of stage 3, stage 4, and certain high-risk forms of disease. Radiation may be directed at the abdomen, lungs, or other affected areas depending on the extent of cancer spread. Modern radiation techniques are designed to improve precision and reduce long-term side effects.

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Recurrence

Recurrence refers to the return of cancer after treatment and a period during which no evidence of disease was detected. Recurrence may occur locally in the original area or in distant parts of the body such as the lungs. The risk of recurrence depends on factors including tumor stage, histology, treatment response, and biological characteristics. Ongoing follow-up care and surveillance imaging are important for detecting recurrence as early as possible and initiating appropriate treatment.

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Relapse

Relapse is another term used to describe the return of Wilms tumor after a child has achieved remission. Relapsed Wilms tumor may require additional chemotherapy, surgery, radiation therapy, stem cell transplantation, or participation in clinical trials. While relapse can be emotionally and medically challenging, advances in salvage therapy have improved outcomes for many children experiencing recurrent disease. Early detection remains important for maximizing treatment options and long-term survival.

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Remission

Remission refers to a period during which there is no detectable evidence of active cancer. Complete remission means that all signs of disease have disappeared following treatment, while partial remission indicates a significant reduction in tumor burden. Achieving remission is a major treatment goal in Wilms tumor care. Even after remission is achieved, ongoing surveillance remains important because recurrence can still occur months or years later.

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Renal Function

Renal function describes how effectively the kidneys filter waste products, regulate fluids, and maintain electrolyte balance. Protecting renal function is a major consideration during Wilms tumor treatment, particularly for children with bilateral disease or those who have undergone nephrectomy. Healthcare teams regularly monitor kidney function through blood tests, urine tests, and clinical assessments. Long-term renal monitoring is an important component of survivorship care for Wilms tumor survivors.

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Stage 1 Wilms Tumor

Stage 1 Wilms tumor is cancer that remains confined to the kidney and has been completely removed through surgery. There is no evidence of spread beyond the kidney, and the tumor can usually be treated successfully with surgery and limited chemotherapy. Children diagnosed with stage 1 favorable histology Wilms tumor generally have an excellent prognosis and among the highest survival rates of all disease stages.

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Stage 2 Wilms Tumor

Stage 2 Wilms tumor occurs when cancer extends beyond the kidney but can still be completely removed through surgery. Although the tumor has grown into nearby tissues or blood vessels, there is no residual disease following surgical treatment. Children with stage 2 disease often receive chemotherapy after surgery to reduce the risk of recurrence and improve long-term outcomes.

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Stage 3 Wilms Tumor

Stage 3 Wilms tumor refers to cancer that remains within the abdomen after surgery or has spread to nearby lymph nodes or tissues. This stage may involve residual microscopic disease, tumor spillage, or incomplete surgical removal. Treatment typically includes a combination of chemotherapy and radiation therapy. Despite requiring more intensive treatment, many children with stage 3 Wilms tumor achieve long-term remission and survival.

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Stage 4 Wilms Tumor

Stage 4 Wilms tumor occurs when cancer has spread to distant organs such as the lungs, liver, bones, or brain. Although stage 4 disease is considered advanced childhood kidney cancer, significant progress in pediatric oncology has improved survival rates. Treatment often involves intensive chemotherapy, surgery, radiation therapy, and comprehensive supportive care. Many children with metastatic Wilms tumor can achieve long-term remission through modern treatment protocols.

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Stage 5 Wilms Tumor

Stage 5 Wilms tumor is diagnosed when tumors are present in both kidneys at the time of diagnosis. Because preserving kidney function is critically important, treatment often begins with chemotherapy to shrink tumors before surgery is performed. Whenever possible, nephron-sparing surgery is used to preserve healthy kidney tissue. Long-term follow-up is essential because children with bilateral disease may face an increased risk of chronic kidney complications.

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Stem Cell Transplant

A stem cell transplant, often referred to as an autologous stem cell transplant in Wilms tumor treatment, is a procedure used to restore bone marrow function following high-dose chemotherapy. The child's own stem cells are collected before treatment and later returned to the body after intensive therapy is completed. Stem cell transplantation is most commonly used in selected cases of relapsed or high-risk Wilms tumor and may provide an additional treatment option when standard therapies are insufficient.

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Surveillance

Surveillance refers to the ongoing monitoring of children after completing Wilms tumor treatment. Surveillance programs typically include physical examinations, imaging studies, blood tests, and assessments of kidney function and overall health. The goal is to detect recurrence early, identify treatment-related complications, and support long-term survivorship. Surveillance remains an important component of care even years after treatment has ended.

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Vincristine

Vincristine is one of the most commonly used chemotherapy drugs in Wilms tumor treatment. It works by interfering with cancer cell division and preventing tumor growth. Vincristine is often combined with dactinomycin and other agents as part of standard treatment protocols. The drug has played a major role in improving survival rates for children with Wilms tumor and remains a cornerstone of modern pediatric oncology therapy.

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Wilms Tumor

Wilms tumor, also known as nephroblastoma, is the most common form of childhood kidney cancer and primarily affects children under the age of five. The disease develops from immature kidney cells and may occur in one kidney or both kidneys. Common symptoms include an abdominal mass, abdominal swelling, blood in the urine, abdominal pain, and high blood pressure. Treatment often involves surgery, chemotherapy, radiation therapy, and long-term follow-up care. Thanks to advances in pediatric oncology, Wilms tumor now has one of the highest survival rates among childhood cancers, particularly when diagnosed and treated early.​​