METASTATIC NEUROBLASTOMA IN CHILDREN OLDER THAN ONE-YEAR - PROGNOSTIC-SIGNIFICANCE OF THE INITIAL METAIODOBENZYLGUANIDINE SCAN AND PROPOSALFOR A SCORING SYSTEM

BACKGROUND, Metaiodobenzylguanidine (mIBG) is a guanethidine analog th at has demonstrated a high sensitivity and specificity in detecting bo ne metastases in about 90% of metastatic neuroblastomas. However, the predictive value of initial mIBG scan in neuroblastoma patients older than 1 year of age regarding response to initial chemotherapy has yet to be ascertained. Therefore, a scoring system for grading the positiv ity of mIBG scans was devised and applied in a retrospective study in an attempt to determine whether this score had a prognostic value in n euroblastoma patients older than 1 year of age at diagnosis. METHODS. Eighty-six children, older than 1 year of age, with metastatic neurobl astomas were homogeneously treated and had a mIBG scan performed at di agnosis and following the induction regimen to assess bone metastases. Each mIBG scan was assigned a reproducible score and the predictive v alue of the initial mIBG score was assessed in order to evaluate respo nse to induction regimen. RESULTS, The relative risk of failing to ach ieve complete remission after four courses of induction therapy was 6. 9 times higher in patients who had more than four mIBG spots at diagno sis. A multivariate analysis including the established prognostic fact ors revealed that the initial mIBG score was the only significant fact or (P < 0.001). CONCLUSIONS. The initial mIBG scan is of prognostic si gnificance to predict response to chemotherapy for metastatic neurobla stoma in children older than 1 year of age. A prospective study compar ing this initial mIBG score with other recently established prognostic factors is warranted. (C) 1996 American Cancer Society.