Wilms tumor

Or nephroblastoma, results from aberrant developmental process within the kidney.

Most common primary malignant renal tumor of childhood.

Approximately 650 children are diagnosed with Wilms tumor each year.

Accounts for more than 90% of primary renal tumors in patients younger than 20 years and 5% of all childhood cancers.

Genetic conditions predispose children to WT and may be present and 10–20% of cases.

Associated congenital anomalies suggest the presence of a genetic predisposition syndrome.

Genitourinary malformations are found in 5% of children with WT, hemihyperplasia in 2 to 3% and aniridia in 1%.

Cure rate 90%.

75% of children present with WT between one and five years of age, most commonly at three years.

The incidence of Wilms tumor is highest among African American children followed by Caucasian children and then Asian children.

Abdominal staging: stage I limited to renal parenchyma, stage II demonstrating invasion into renal pelvis or renal capsule, stage III tumor outside the capsule remaining in the abdomen, including findings of positive margins, confirmation of tumor spill or rupture, positive lymph nodes, or tumor without upfront resection, Stage IV implies metastatic disease most commonly lungs in liver.

In children with stage I disease with favorable histology abdominal radiation is not necessary if patients receive postoperative vincristine and dactinomycin chemotherapy.

To avoid tumor spread from malignant tumors, biopsy is not routinely recommended before upfront surgery if the patient has a resectable disease.

For patients with unresectable disease a biopsy should be acquired, but never a needle aspiration:either a core biopsy or an open biopsy is suggested.

16-year relapse free interval for stage I/favorable histology patients is 92-98.9% for patients treated with 6 months of vincristine and dactinomycin.

Post nephrectomy chemotherapy with vincristine alone in children with stage I/favorable histology has an event free survival of 90% and an overall survival of 96% suggesting that single agent treatment in this situation is as effective as two-drug management(UKCCSG).

Optimal surgery includes a transperitoneal approach with inspection and biopsy of regional lymph nodes, and radical or modified radical nephrectomy.

Children with resectable unilateral WT typically receive upfront nephrectomy followed by adjuvant therapy.

Some patients can have adjuvant therapy omitted if they are at very low risk: younger than two years, tumor weight of less than 550 g and stage I disease.

The initiation of therapy without biopsy is recommended for patients younger than 10 years with bilateral renal tumors or with known predisposition syndromes because the likelihood of the tumors being Wilms tumor is so high.

Tumor involving adjoining organs and invading the vena cava at or above the liver should be treated with preoperative chemotherapy rather than attempting to excise these lesions.

7% of children have bilateral disease.

Bilateral disease tends to occur in children that younger ages, more often in girls and is an important risk factor for the development of renal failure.

Patients born with a WT1 mutation pretend a poor prognosis for renal function.

Most children present with a solitary tumor in one kidney.
10% of children have multifocal tumors in a single kidney.
Most patients present with abdominal swelling and or the presence of an abdominal mass (83%) with or without abdominal pain, fever, hematuria, and hypertension.
Less common features include varicocele, hernia, enlarged testicle, congestive heart failure, hypoglycemia, Cushing’s syndrome, pleural effusion, acute abdomen, and acute rupture, bleeding, and shock.
Calcifications of the tumor appear in approximately 5-10% of Wilms tumors, compared to 60-70% of neuroblastomas.

Almost 10% of patients with WT have a coagulopathy, an acquired von Willebrand’s disease.

In the presence of bilateral disease patients should be given preoperative chemotherapy followed by partial nephrectomies or wedge resection with preservation associated much normal renal tissue associated possible.

Imaging studies confirm metastases and biopsies are rarely needed to do so.

The presence of anaplasia is an adverse prognostic factor.

The tumor can extend locally to perirenal soft tissues, renal vein, and vena cava.

The most common sites of  hematogenous metastasis include the lung, and liver, and spread to regional lymph nodes.

It rarely metastasizes to bone and brain.

Initial testing recommended for children with a suspicious abdominal mass includes history and physical, blood pressure measurements, assessment for genitourinary malformations and other congenital abnormalities associated with WT.

Abdominal sonogram is typically the first imaging test and can quickly ascertain the presence of a mass and its origin of origin.

Abdominal CT or MRI can evaluate the extent involvement of the renal mass.

Imaging can differentiate tumors a primary renal origin from extrarenal tumors and from benign and malignant diseases and determine whether a child has unilateral or bilateral kidney involvement with the presence of metastatic disease.

Surgical goals include removal of all disease without rupturing the tumor, no gross tumor spell, accurate lymph node staging, and complete pathologic evaluation.

Surgical approaches are to avoid tumor spillage, and surgery includes assessments by abdominal exploration, lymph node sampling of a minimum of five nodes from renal hilum paracaval and periaortic regions, assessment for tumor rupture, ascites, and retroperitoneal adenopathy.

Any tumor spillage is classified as stage III and radiation therapy is recommended.

Adjuvant radiation therapy is recommended for patients at higher risk after surgery but not for those with lower stage, lower risk disease.

Adjuvant whole lung irradiation is recommended for patients with lung metastasis.

Most patients require a unilateral radical ureteronephrectomy..

Nephron sparing surgery is reserved for patients with bilateral disease, multifocal unilateral disease or in those who are genetically predisposed.

underlying genetic anomalies can predispose patients to dysplastic renal tissue or premature tissue loss.

Pathological evaluation determines molecular markers and histology.

Increase risk and higher incidence of metastases associated with LOH bio markers.

factors associated with increase need for intensive therapy include older age at diagnosis, unfavorable histology, higher stage, larger tumor weight, unfavorable molecular biomarkers, and incomplete lung nodule response to neoadjuvant chemotherapy at week six.

Neoadjuvant and/or adjuvant chemotherapy in combination with surgery improve survival for most children with Wilms tumor.

Agents utilized include vincristine, dactomycin, doxorubicin cyclophosphamide, etoposide.

Neoadjuvant chemo therapy regimens are used for patients with contraindications to or any Bility to undergo upfront nephrectomy and include combinations of the above agents.

After six weeks of neoadjuvant chemo therapy, lesions are reevaluated as to whether or not they or resectable.

Neoadjuvant  therapy is continued for as long as 12 weeks prior to definitive management.

Adjuvant chemotherapy is initiated no later than 14 days after nephrectomy.






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