Abstract: |
Purpose Relapse-free survival (RFS) is a powerful measure of treatment efficacy. We describe the sensitivity of standard surveillance studies for detecting relapse of neuroblastoma (NB). Patients and Methods The patients were in complete/very good partial remission of high-risk NB; routine monitoring revealed asymptomatic and, therefore, unsuspected relapses in 113 patients, whereas 41 patients had symptoms prompting urgent evaluations. Assessments every 2 to 4 months included computed tomography, iodine-131-metaiodobenzylguanidine (<sup>131</sup>I-MIBG; through November 1999) or iodine-123- metaiodobenzylguanidine (<sup>123</sup>I-MIBG) scan, urine catecholamines, and bone marrow (BM) histology. Bone scan was routine through 2002. Results <sup>123</sup>I-MIBG scan was the most reliable study for revealing unsuspected relapse; it had an 82% detection rate, which was superior to the rates with <sup>131</sup>I-MIBG scan (64%; P =.1), bone scan (36%; P <.001), and BM histology (34%; P <.001). Among asymptomatic patients, <sup>123</sup>I-MIBG scan was the sole positive study indicating relapse in 25 (27%) of 91 patients compared with one (4.5%) of 22 patients for <sup>131</sup>I-MIBG scan (P =.04) and 0% to 6% of patients for each of the other studies (P <.001). Patients whose monitoring included <sup>123</sup>I-MIBG scan were significantly less likely than patients monitored by <sup>131</sup>I-MIBG scan to have an extensive osteomedullary relapse and had a significantly longer survival from relapse (P <.001) and from diagnosis (P =.002). They also had significantly longer survival than patients with symptomatic relapses (P =.002). Conclusion <sup>123</sup>I-MIBG scan is essential for valid estimation of the duration of RFS of patients with high-risk NB. Without monitoring that includes <sup>123</sup>I-MIBG scan, caution should be used when comparing RFS between institutions and protocols. © 2009 by American Society of Clinical Oncology. |