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Wilms'
tumor is an embryonal cancer of the kidney composed of blastemal,
stromal, and epithelial elements. Genetic abnormalities have been
implicated in the pathogenesis, but familial inheritance accounts
for only 1 to 2% of cases. Diagnosis is made by ultrasound and abdominal
CT scan and confirmed by biopsy. Treatment may include surgical
resection, chemotherapy, and radiation therapy.
Wilms' tumor usually presents in children < 5 yr but occasionally in older children and rarely in adults. Wilms' tumor accounts for about 6% of cancers in children < 15 yr. Bilateral synchronous tumors occur in about 4% of cases, with bilateral disease more common in very young children, especially girls. A chromosomal deletion of WT1, the Wilms' tumor suppressor gene, has been identified in some cases. Other associated genetic abnormalities include deletion of WT2 (a 2nd Wilms' tumor suppressor gene), deletion of chromosome 16, and duplication of chromosome 12.
About 10% of cases manifest other congenital abnormalities, especially GU abnormalities, but also commonly hemihypertrophy (asymmetry of the body). WAGR syndrome is the combination of Wilms' tumor (with WT1 deletion), aniridia, GU malformations (eg, renal hypoplasia, cystic disease, hypospadias, cryptorchidism), and mental retardation.
Symptoms and Signs
The most frequent presentation is a painless, palpable abdominal mass. Less frequent findings include abdominal pain, hematuria, fever, anorexia, nausea, and vomiting. Hematuria (occurring in 15 to 20%) indicates invasion of the collecting system. Hypertension may occur if compression of the renal pedicle or renal parenchyma causes ischemia.
Diagnosis
Abdominal ultrasound determines the cystic or solid nature of the mass and whether the renal vein or vena cava is involved. Abdominal CT is needed to determine the extent of the tumor and spread to regional lymph nodes, the contralateral kidney, or liver. The diagnosis is confirmed by biopsy of the mass. Renal arteriography, vena cavography, retrograde urography, or excretory urography seldom is required. Chest x-ray (and possibly chest CT) is needed to detect metastatic pulmonary involvement at initial diagnosis.
Prognosis
and Treatment
Prognosis depends on histology (favorable or unfavorable), the stage at diagnosis, and the patient's age (younger is better). The outcome for children with Wilms' tumor is excellent. Cure rates for lower stage disease (localized to the kidney) range from 85 to 95%. Even children with more advanced disease fare well, with cure rates ranging from 60% (unfavorable histology) to 90% (favorable histology). Recurrences do occur, typically within 2 yr of diagnosis. Cure is possible in children with recurrent cancer. Outcome after recurrence is better in children who presented initially with lower stage disease, whose tumors recur at a site that has not been irradiated, who relapse > 1 yr after presentation, and who receive less intensive treatment initially.
The National Wilms' Tumor Study Group has established staging criteria and guidelines for treatment. Prompt surgical exploration of potentially resectable lesions is indicated, with examination of the contralateral kidney. If the cancer is unilateral and limited to the kidney or if extension is minimal, complete resection by nephrectomy is performed, followed by treatment with vincristine and actinomycin D. If a unilateral cancer has spread extensively or if the disease is bilateral, chemotherapy with actinomycin D and vincristine , with or without radiation therapy, is used. Children with more advanced disease also receive doxorubicin . Other frequently used drugs include cyclophosphamide , ifosfamide , and etoposide . Children with very large nonresectable tumors or bilateral tumors are candidates for chemotherapy followed by reevaluation and possibly resection.
Last full review/revision November 2005
Content last modified November 2005
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