Staging problems in the pre-operative chemotherapy of Wilms' tumour

To determine the effect of the International Society of Paediatric Oncology (SIOP) Wilms' tumour protocols (pre-operative chemotherapy based on clinical and radiological findings, with no prior tumour verification by open or needle biopsy) on subsequent intra-operative tumour diagnosis and staging.

The diagnosis and staging of possible Wilms' tumour by clinical, ultrasonographic and radiological assessment were compared with the intra-operative findings in 14 consecutive children (1-12 years of age) treated between 1989 and 1994.

A diagnosis of Wilms' tumour was histologically verified in 11 of 14 children. In two children, verification was not possible due to complete necrosis of the tumour following pre-operative chemotherapy. In a 12-year-old boy with an estimated stage IV disease due to a solitary lung metastasis, a renal cell carcinoma was revealed in the nephrectomy specimen while subsequent thoracotomy revealed dysmorphic but not malignant tissue. The estimated tumour stage was correct with regard to localized or metastatic disease in nine of 11 children with histologically confirmed Wilms' tumour, while in two children with an estimated stage II tumour, liver metastases were found intra-operatively and the tumour was upstaged to IV.

Exact tumour diagnosis and staging was difficult in these patients. Although the accuracy of tumour staging depends on the sensitivity of radiological and ultrasonographic examinations, difficulties in tumour diagnosis may be overcome by biopsies of the primary tumour. The justification of upstaging a low-stage I/II tumour to stage III, provoking a more intense post-operative treatment, should be proven by prospective randomized studies. The decision to perform a primary tumour biopsy would be facilitated if possible subsequent deterioration of outcome could be excluded.