Response Criteria

The evaluation of the tumor response to the treatment is mandatory; however, the correlation between initial response and long-term outcome is still weaker in neuroblastoma than prednisone response in acute lymphoblastic leukemia. The criteria for defining response (Brodeur et al. 1993) are shown in Table 7.10. All test results that were abnormal at diagnosis need to be reinvestigated after 3-4 months, after completion of each major therapeutic step (e.g., at the end of chemotherapy, after surgery). Most protocols require additional evaluations for disease response during the treatment period and following the completion of therapy (Therassa et al. 2000).

Currently, the response status is assessed using standard radiographic measurements to determine tumor size and evidence of metastases in addition to histological evaluation of the bone marrow. Many efforts of refinement are being undertaken such as PCR-based detection of minimal residual disease in the bone marrow (Chap. 11), MYCN-DNA levels in serum (Combaret et al. 2002), and antibody-based scintigraphy (Chap. 14). These studies need confirmation by other independent groups before they are adopted for standard response evaluation reporting.

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