Diagnostic accuracy of CT based staging of Wilms’ tumor in the era of Multislice CT

Wilms’ tumor (WT) is the most common pediatric renal tumor and the fifth most common childhood cancer. This tumor has good outcome, with current survival rate of 86-96%.

There are two approaches in treating these tumors: The SIOP (International Society of Paediatric Oncology) approach advocates a short course of chemotherapy prior to surgery, followed by stage appropriate chemotherapy with or without radiotherapy while the NWTS (National Wilms’ Tumor Study group) approach warrants upfront surgery resulting in accurate staging and appropriate therapy.

Both approaches have pros and cons. The advantage of SIOP approach is down-staging caused by pre-operative chemotherapy. However, patients treated with SIOP approach are often treated without a biopsy (within acceptable risk) and patients may receive a suboptimal chemotherapy for a non-WT or in rare cases, chemotherapy may be administered to benign tumors. The advantage of NWTS approach is accurate staging and stage based therapy. However, with NWTS approach, there is a higher incidence of stage III disease, commonly due to spillage, that warrants radiotherapy and increase in the chemotherapeutic regimen drugs and duration.

There is a potential to achieve a “win-win†situation if patients could be preselected for eitherapproach. The unilateral non-metastatic tumors which are intra-capsular / non-adherent to adjacent structures/ those who do not have extensive venous thrombosis can be safely resected out upfront, while those who have

locally advanced disease could benefit from pre-operative chemotherapy.

 These features can be identified on imaging, however, CT has often been criticized in the past for poor accuracy. In the current era of multislice CT, there is a possibility that evaluation of local spread has become more reliable, thus improving the accuracy of CT imaging.

 In this retrospective study, we want to evaluate the diagnostic accuracy of CT in staging of Wilms’ tumor.

 If CT is found to be reliable, it may be successfully used in triage of patients in the future.The electronic data base will be searched for 50 consecutive WT cases having an in-house CT scan done within 15 days of surgery, intra-operative findingsand histopathological report. Patients with complete information will be included on the study and an electronic data base of CT findings, relevant intra-op findings and histopathology will be created.

 Two radiologists (Dr. Seema A. Kembhavi and Dr. PalakPopat) who are blinded to surgical and histological findings will review the CT scans. Surgical notes and histopathology data will be retrieved from EMR by a third person (Dr. Garima).

 Following information will be collected (CRF has details)

• Age
• Sex : male/female
• Laterality: right/left
• Extent of involvement in the kidney
• Size of the mass
• Renal vein thrombosis, if present, its extent into IVC
• Renal sinus involvement
• PC system involvement
• Ureteric involvement
• Any e/o capsular involvement or extra-capsular spread
• Adenopathy
• Spillage, ascites, peritoneal disease
• Metastases
• Contralateral kidney

 CT stage will be assigned based on CT findings by each observer. In case of discordance, a final stage will be decided up on agreement. This information will be compared with Reference standard – surgical noted and histopathology.

 For patients with stage IV disease, local stage of tumor will be assessed as I/II/III.

 For the patients who have received pre-operative chemotherapy, the post chemotherapy scan will be evaluated.