reduces the renal failure rate following bilateral Wilms’ tumor therapy.

–The overall 2-year survival rate is higher than 80 % with this approach, and the nephrectomy rate drops by 50 % in patients with bilateral Wilms’ tumor.

4.2.11 Surgical Complications

•The overall surgical complication rate for Wilms’ tumor is approximately 15–20 %.

•Surgical complications may include the following:

–Small-bowel obstruction (7 %)

–Hemorrhage (6 %)

–Wound infection, hernia (4 %)

–Vascular complications (2 %)

–Splenic and intestinal injury (1.5 %)

Currently, Patients with High Risk Wilms’ Tumor Are Treated as Follows

•Focal anaplastic stage I–III Wilms’ tumors and diffuse anaplastic stage I Wilms’ tumors:

–Nephrectomy followed by vincristine, actinomycin-D, and doxorubicin in addition to local radiotherapy.

•Focal anaplastic stage IV Wilms’ tumors and diffuse anaplastic stage II–III tumors:

–Nephrectomy followed by chemotherapy including vincristine, actinomy- cin-D,doxorubicin,cyclophosphamide, etoposide, and carboplatin in addition to local radiotherapy

•Stage IV diffuse anaplastic Wilms’ tumors:

–More aggressive treatment is delivered; nephrectomy is followed by initial irinotecan and vincristine administration, which in turn is followed by actinomycin-D, doxorubicin, cyclophosphamide, carboplatin, etoposide, and radiotherapy.

4.2.12 Prognosis and Outcome

•The overall 5-year survival in children with Wilms’ tumor is estimated to be approximately 90 %.

•This however is variable and the prognosis is highly dependent on the stage and treatment of tumor.

•Tumor-specific loss-of-heterozygosity (LOH) for chromosomes 1p and 16q identifies a subset of Wilms’ tumor patients who have a significantly increased risk of relapse and death.

•LOH can now be used as an independent prognostic factor together with disease stage to give intensive treatment.

•Patients with synchronous bilateral tumors have a 70–80 % survival rate, whereas those with metachronous tumors have a 45–50 % survival rate.

•Patients with anaplastic Wilms’ tumor have a worse prognosis compared with favorable histology Wilms’ tumor. The 4-year overall survival rates are as follows:

–Stage I: 83 %

–Stage II: 83 %

–Stage III: 65 %

–Stage IV: 33 %

•Chemotherapy and radiation therapy can induce second malignant neoplasms.

–Most secondary malignant neoplasms reported (e.g., bone tumors, breast and thyroid cancers) have occurred in irradiated areas. Nevertheless, certain chemotherapeutic agents, including doxorubicin, dactinomycin, and vincristine, may contribute to an increased risk for secondary malignancies.

•Bilateral, high-stage tumors with unfavorable histology are associated with a poor prognosis in spite of multimodal therapy.

•Children with Wilms’ tumor have a minimal risk for impaired renal function but bilateral disease and radiotherapy can further compromise the renal function.

•Several cytotoxic agents may damage the liver of patients treated for Wilms’ tumor, including dactinomycin and radiation induced hepatitis.

Overall Prognosis of Wilms’ Tumor

•Stage I: 98 % 4-year survival; 85 % 4-year survival if anaplastic.

•Stage II: 96 % 4-year survival; 70 % 4-year survival if anaplastic.

•Stage III: 95 % 4-year survival; 56 % 4-year survival if anaplastic.

•Stage IV: 90 % 4-year survival; 17 % 4-year survival if anaplastic.

•Stage V: The 4-year survival was 94 % for those patients whose most advanced lesion was stage I or stage II; 76 % for those whose most advanced lesion was stage III.

•Patients with synchronous bilateral tumors have a 70–80 % survival rate whereas those with metachronous tumors have a 45–50 % survival rate.

•Patients with anaplastic Wilms’ tumor have a worse prognosis compared with favorable histology Wilms’ tumor; the 4-year overall survival rates are 83 %, 83 %, 65 % and 33 % for stages I, II, III, and IV, respectively.

•Patients with Wilms’ tumor may develope hepatic veno-occlusive disease.

•Congestive heart failure is a well-known complication of the administration of anthracyclines.

•Radiation therapy can affect pulmonary function.

•Ovarian and testicular failures can follow whole-abdomen irradiation in childhood or alkylating agents.

•Radiation therapy may affect the growth.

•Relapse of Wilms’ tumor:

–The lungs are the most common site of relapse.

–This site is affected in more than two thirds of children who have a relapse.

–The tumor bed is the site of relapse only in about one fourth of patients.

–The brain and the bones are not usual sites of relapse for Wilms’ tumors with favorable histology.

4.2.13 Extrarenal Wilms’ Tumors

•Extrarenal Wilms’ tumor is extremely rare and occurs predominantly in children.

•The presence of an extrarenal Wilms’ tumor excludes a primary tumor in the kidney.

•Most of the cases that have been reported involved the retroperitoneum.

•These tumors can occur in isolation or in association with other tumors usually teratomas.

•The diagnostic criteria necessary to establish the diagnosis include absence of primary kidney tumor and supernumery kidney.

•The origin of Wilms’ tumor is controversial.

•There are hypotheses explaining the origin of extrarenal Wilm’s tumor such as:

–From ectopic metanephric blastema: This hypothesis is supported by the fact that the majority of these tumors occur in the retroperitoneal region. However the presence of extra-renal Wilms’ tumor cephalad to kidney argues against it.

–From primitive mesodermal tissue: This hypothesis is based on the occurrence of extrarenal Wilms’ tumor in the cervix, vagina and inguinal canal, where there is a persistent mesonephric duct remnant.

–Connheim’s cell rest theory: This is a common hypothesis where cells with persistent embryonal potential undergo malignant transformation at any point of time.

•Reported location of Extrarenal Wilms’ tumor include:

–The retroperitoneum

–Inguinal region

–Endocervix, Uterus

–Epididymis

–Ovotestis

–Vagina

–Paraspinal

–Paravesical

•The staging and management of extrarenal Wilms’ tumor are similar to Renal Wilms’ tumor.