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Intensive chemotherapy with stem cell support-experience in pediatric solid tumours.

A recent Consensus Conference in Lyon reviewed the role of high-dose therapy with stem cell rescue in a variety of malignancies including childhood tumours. The conclusion was that with the exception of metastatic neuroblastoma there is still no proven role for this treatment strategy. It is more than 10 years since this approach was used in neuroblastoma and it has subsequently been applied to most of the common childhood solid tumours. Although a single randomised study has suggested that the progression-free survival is significantly prolonged with high-dose melphalan, the superiority of this over continued intensive conventional therapy is unclear. It seems likely that a selected subgroup of children with stage IV disease may benefit from megatherapy and the results of current randomised trials are awaited. In rhabdomyosarcoma, the duration of treatment may be shortened by dose escalation, but the impact on the outcome in very high-risk patients remains unproven. In Ewing's sarcoma, there has been difficulty defining high-risk patients, but recent studies suggest that megatherapy may have a role in patients with bone or bone marrow disease who have little chance of long-term survival with conventional chemotherapy approaches. In brain tumours, the results have been disappointing for gliomas, but there is currently enthusiasm about a possible role in the chemosensitive primitive neuroectodermal tumours. In this group of diseases which are inherently chemosensitive, the poor results from chemotherapy in the past have resulted from a failure to achieve appropriate drug levels at the tumour site and this may be potentially overcome by dose escalation. In Wilms' tumour, although the overall cure rate is very high, there appears to be a useful role for megatherapy in certain high-risk relapsed patients who have little chance of cure with conventional salvage therapy. There is an urgent need for international collaboration to design randomised studies which will as rapidly as possible address the issue of the role of these expensive and high morbidity procedures in childhood cancer.