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Journal of Clinical Oncology, Vol 22, No 19 (October 1), 2004: pp. 3909-3915 © 2004 American Society of Clinical Oncology. DOI: 10.1200/JCO.2004.07.144 Scintigraphic Response by 123I-Metaiodobenzylguanidine Scan Correlates With Event-Free Survival in High-Risk NeuroblastomaFrom the Division of Hematology/Oncology, Department of Pediatrics, Department of Radiology, and Stem Cell and Graft Engineering Laboratory, Northwestern University and Children's Memorial Hospital, Chicago, IL; Biostatistics Core Facility, The Robert H. Lurie Comprehensive Cancer Center, and Northwestern University Feinberg School of Medicine, Chicago, IL; Children's Healthcare of Atlanta, Emory University School of Medicine, Atlanta, GA; James Whitcomb Riley Hospital for Children, Indiana University School of Medicine, Indianapolis, IN. Address reprint requests to Morris Kletzel, MD, Northwestern University, Children's Memorial Hospital, 2300 Children's Plaza, Box #30, Chicago, IL 60614; e-mail: mkletzel{at}northwestern.edu
PURPOSE: To investigate whether response to induction therapy, evaluated by metaiodobenzylguanadine (MIBG) and bone scintigraphy, correlates with event-free survival (EFS) in children with high-risk neuroblastoma (NB). PATIENTS AND METHODS: Twenty-nine high-risk NB patients were treated prospectively with an intensive induction regimen and consolidated with three cycles of high-dose therapy with peripheral blood stem-cell rescue. The scintigraphic response was evaluated by MIBG and bone scans using a semi-quantitative scoring system. The prognostic significance of the imaging scores at diagnosis and following induction therapy was evaluated.
RESULTS: A trend associating worse 4-year EFS rates for patients with versus without osteomedullary uptake on MIBG scintigraphs at diagnosis was seen (35% ± 11% v 80% ± 18%, respectively; P = .13). Similarly, patients with positive bone scans at diagnosis had worse EFS than those with negative scans, although the difference did not receive statistical significance (34% ± 10% v 83% ± 15%, respectively; P = .06). However, significantly worse EFS was observed in patients with a postinduction MIBG score of
CONCLUSION: MIBG scores
During the last 20 years, advances in the understanding of neuroblastoma (NB) tumor biology have resulted in the identification of prognostic variables that have been used to define risk-group criteria and guide therapy.1-2 Treatment tailored according to risk-group stratification has resulted in improved outcome and diminished toxicity for children with low- and intermediate-risk disease.3-4 However, children with high-risk NB have had only a slight improvement in outcome despite treatment with aggressive multimodality therapy. Currently, less than 30% of high-risk patients are cured of their disease.5-7
The modest improvement in survival of high-risk patients is thought to result, at least in part, from intensification of therapy.8 A number of nonrandomized studies have suggested that dose-intensification with myeloablative therapy and autologous bone marrow transplant results in an improved outcome for high-risk NB patients.5,9-11 The superiority of myeloablative therapy and autologous bone marrow transplant over conventional dose chemotherapy has been definitively demonstrated in a randomized study conducted by the Children's Cancer Group.6 Recently, we and others have reported 3-year EFS rates of Early response to therapy has been shown to have prognostic significance in many types of childhood cancers.19-21 Metaiodobenzylguanidine (MIBG) uptake has also been shown to be a highly sensitive and specific method to detect NB and to evaluate the response to therapy.22,23 Several retrospective studies have indicated that a positive MIBG scan at diagnosis or before myeloablative therapy may be predictive of a poor outcome in high-risk patients.24-27
In this study, we prospectively evaluated osteomedullary uptake on diagnostic and postinduction therapy MIBG and 99mTc-diphosphonate bone scintigraphs in 29 high-risk NB patients who received uniform intensive multimodality treatment that included three cycles of high-dose chemotherapy with PBSC rescue.12 The nuclear medicine images were semi-quantitatively scored using criteria previously described,28 and the prognostic significance of the imaging scores was evaluated. Our results suggest that patients with MIBG scores of
Patients The clinical characteristics of the initial 26 patients enrolled on the Chicago Pilot II protocol at Children's Memorial Hospital (Chicago, IL) have been published previously.12 Three subsequent patients who were enrolled on the Chicago Pilot II study following that report are included in this analysis, including a child who relapsed with local and widely disseminated disease after initial treatment with surgery alone for stage 2B disease. Two additional stage 4 patients were transferred to our institution, after receiving the induction therapy outlined in the study, for consolidation therapy with the three cycles of high-dose chemotherapy and PBSC rescue followed by local radiation and 13-cis-retinoic acid. Because toddlers between the ages of 12 and 18 months of age with stage 4 disease have been reported to have better outcomes than older patients,29,30 we restricted the current study to the 28 high-risk patients with stage 4 disease who were older than 18 months of age at diagnosis, and the single relapsed patient described above. The Chicago Pilot II protocol was approved by the Children's Memorial Hospital institutional review board, and written informed consent was obtained for each patient before the initiation of treatment. Written informed consent for consolidation therapy was also obtained for each of the patients transferred to our institution after induction therapy. The diagnosis of NB was based on either histologic examination of tumor tissue or by bone marrow infiltrated with tumor cells and elevated urinary catecholamine levels. MYCN copy number was analyzed at the time of diagnosis either by Southern blot analysis or fluorescence in situ hybridization at the Pediatric Oncology Group or Children's Oncology Group reference laboratories using standard techniques.14,17,31 All patients were staged according to International Neuroblastoma Staging System (INSS) criteria,32 and extent of disease was evaluated by computed tomography of the chest and abdomen, 99Tc bone scan, bilateral bone marrow aspirates and biopsies, and MIBG scan. The response to therapy was assessed according to INSS criteria after four cycles of induction chemotherapy and again following completion of the induction regimen (seven cycles of therapy), just before consolidation with high-dose therapy and PBSC rescue.
Treatment
Hematopoietic Stem-Cell Processing
MIBG Analysis MIBG scintigrams and 99Tc bone scans were reviewed by two radiologists (D.M.E.B. and R.M.S.) without knowledge of the interpretation of the original report. The diagnostic scintigrams were initially interpreted by one of four board-certified radiologists. A consensus was then achieved between the original interpretation and the retrospective review of the MIBG studies. Twenty-five MIBG scans and 29 bone scans performed at diagnosis were available for review. For two patients initially treated elsewhere, the diagnostic MIBG was not retrievable for review but review of the written radiographic reports did allow interpretation of whether the scans were positive or negative, and so these patients was considered assessable for radiographic response, but imaging scores could not be determined. Two patients were excluded from the MIBG analysis for the following reasons: no scan was performed at diagnosis (n = 1); and the patient had an allergic reaction to contrast before the initial scan (n = 1). Twenty-four MIBG studies and 27 bone scans were performed before the three cycles of high-dose therapy and stem-cell rescue. The five patients who did not have assessable MIBG scans before consolidation included two patients with tumors that were not MIBG-avid, one patient who had a toxic death during induction therapy, and the two patients mentioned above who were excluded at diagnosis.
MIBG and Bone Scintigram Scoring
Statistical Analysis
Patient Characteristics The clinical and biologic characteristics of the 29 patients included in this study are shown in Table 1. The median age at diagnosis was 43 months (range, 19 to 176 months). Twenty-eight of the patients had stage 4 disease at diagnosis, and tumor MYCN amplification was present in 10 cases. An additional patient who developed widely disseminated relapsed disease after an initial diagnosis of a stage 2B tumor that lacked MYCN amplification was included in the analysis. The 4-year estimated EFS rate for the entire cohort was 45% ± 9%, with a median follow-up of 72 months (range, 30 to 95 months) from diagnosis for the disease-free surviving patients.
Diagnostic MIBG and Bone Scintigraphy Twenty-nine patients had diagnostic imaging studies that were available for analysis. Twenty-five (93%) of 27 patients had MIBG avid tumors, and 20 had evidence of osteomedullary disease (Table 2). We were unable to determine MIBG scores in two patients who were initially treated elsewhere because only radiographic reports were available for review. The diagnostic MIBG score was calculated for 25 of the patients in our study, and the mean score was 8 (range, 0 to 27) with a median score of 4. Discrepancies between the MIBG and bone scintigraphy results were observed in one child who had an abnormal bone scintigram but had no abnormal osteomedullary localization on MIBG scan. No patient in this series with abnormal osteomedullary MIBG localization at diagnosis had a normal initial bone scintigram. Patients with osteomedullary disease detected by MIBG imaging at diagnosis tended to do worse, with a 4-year EFS rate of 35% ± 11%, compared to 80% ± 18% for those without osteomedullary uptake (P = .13; Table 2; Fig 1A). However, no difference in outcome was seen in patients with diagnostic MIBG scores 8 versus those with scores less than 8 (6-year EFS, 42% ± 14% v 55% ± 15%, respectively; P = .43).
The diagnostic bone scan was positive in 23 of the 29 patients. The estimated 4-year EFS was better for patients with negative diagnostic bone scans compared to those with abnormal skeletal uptake (83% ± 15% v 34% ± 10%, respectively; P = .06; Table 2; Fig 1B). The diagnostic bone scan scores were calculated for all 29 of the patients. The mean bone scan score was 9 (range, 0 to 20) with a median score of 9 as well. No difference in outcome was observed in patients with diagnostic bone scan scores above or below the mean (40% ± 13% v 50% ± 13%, respectively; P = .54).
MIBG and Bone Scintigraphy Following Induction Therapy
Fifteen of the 24 patients who were evaluated by MIBG scan postinduction therapy had persistently abnormal uptake; 10 patients had uptake in the primary tumor and eight patients had persistent positive osteomedullary uptake (Table 3). The mean postinduction MIBG score was 3 (range, 0 to 22) with a median score of 0. Patients with MIBG scores
Twenty-seven patients had bone scans performed after the completion of induction therapy. The bone scintigrams were abnormal in 10 patients. The mean postinduction bone scan score was 1 (range, 0 to 10) with a median score of 0. The bone scan score was not predictive of outcome. The 4-year EFS was 33% ± 16% for patients with a bone scan score 2 compared to 56% ± 12% for those with a bone scan score of less than 2 (P = .48). Similarly, when the scoring system was not used, no statistically significant difference in EFS was seen in patients with abnormal bone scans compared to those with normal bone scans (30% ± 14% v 59% ± 12%, respectively; P = .32; Table 3).
The results of this prospective analysis of 29 children with high-risk NB indicate that postinduction therapy MIBG imaging studies can be utilized to identify a subset of ultrahigh-risk patients. A trend associating worse outcome with abnormal osteomedullary uptake by MIBG or bone scintigraphy at diagnosis was also observed, but the difference was not statistically significant. In an effort to quantitatively measure metastatic disease, each image was analyzed using a scoring system we have previously described.28 Although the imaging scores calculated for the diagnostic MIBG and bone scans were not prognostic, a strong association between EFS and the postinduction MIBG score was observed. Patients with MIBG scores 3 following induction therapy had significantly worse EFS than those with scores less than 3. A trend was also seen associating a worse outcome with any abnormal MIBG osteomedullary uptake on postinduction scans, but the difference was not statistically significant. In contrast, uptake on bone scans obtained following induction therapy did not correlate with EFS. These observations are consistent with the results we previously reported in a retrospective analysis of MIBG scintigraphy in NB patients.28 In that study, we evaluated the outcome of 30 infants and older children with stage 4 NB according to initial and postinduction MIBG and bone imaging studies.28 Although the mean diagnostic MIBG score was slightly higher in the previous study (mean score of 10 v 8), a trend associating worse outcome with diagnostic MIBG scores above the mean was observed in patients older than 1 year of age. Furthermore, similar to the current study, a trend was seen associating inferior outcome with persistent osteomedullary MIBG uptake following induction therapy. In contrast, diagnostic and post-therapy bone scans were not predictive of outcome in the retrospective study.
Other retrospective studies have also indicated that MIBG scintigraphy has prognostic value in children with high-risk NB.24,36 Osteomedullary uptake before myeloablative therapy and bone marrow transplant was associated with poor outcome in a large series reported by the European Bone Marrow Transplantation Registry.37 In another study, Suc et al24 evaluated the predictive value of diagnostic MIBG scans in 86 children older than 1 year of age with metastatic NB. In an effort to systematically measure MIBG positivity, these investigators devised a scoring system in which the skeleton was divided into seven zones, and each zone was scored as either negative (0) or positive (1). Patients with scores > 4 at diagnosis had a significantly higher risk of failing to achieve a complete response to induction therapy. More recently, Matthay et al27 conducted a retrospective analysis of 75 children with high-risk NB to determine if early response to therapy measured by MIBG correlated with EFS. In their study, the MIBG scans were scored using a system that was originally developed at the Institute Curie. Similar to our scoring system, in the Curie system, the skeleton is divided into nine zones, with a tenth zone used to score extraosseous metastases. Each zone is scored from 0 to 3, depending on the extent of involvement, with absolute total scores ranging from 0 to 30. Matthay et al also calculated a relative MIBG score for each patient, which was defined as the absolute score/diagnostic score. Similar to our results, improved EFS was seen in patients with metastatic response to induction therapy, defined as a relative score of Taken together, the results of our study and other studies indicate that early response to therapy is highly prognostic in NB. Children with persistent osteomedullary uptake on MIBG scintigraphy following induction therapy represent an ultrahigh-risk group of NB patients. Furthermore, measuring the osteomedullary response using our scoring system appears to provide additional information that can help distinguish the patients who have a high likelihood of long-term remission with intensive, multimodality therapy from those that are destined to fail. Alternative therapeutic strategies such as MIBG radiotherapy,38,39 biologic agents including retinoids,40-41 tyrosine kinase inhibitors,42 antiangiogenic agents,43,44 and immunotherapy,45,46 as well as novel chemotherapeutic drugs,47-49 should be considered for this subset of ultrahigh-risk patients.
The authors indicated no potential conflicts of interest.
Supported in part by the Friends for Steven Pediatric Cancer Research Fund and the Robert H. Lurie Comprehensive Cancer Center, National Institutes of Health, National Cancer Institute Core Grant No. 5P30CA60553C. Authors' disclosures of potential conflicts of interest are found at the end of this article.
1. Evans AE, D'Angio GJ, Propert K, et al: Prognostic factors in neuroblastoma. Cancer 59:1853-1859, 1987[CrossRef][Medline]
2. Weinstein JL, Katzenstein HM, Cohn SL: Advances in the diagnosis and treatment of neuroblastoma. Oncologist 8:278-292, 2003
3. Cohn SL, Look AT, Joshi VV, et al: Lack of correlation of N-myc gene amplification with prognosis in localized neuroblastoma: A Pediatric Oncology Group study. Cancer Res 55:721-726, 1995
4. Matthay KK, Perez C, Seeger RC, et al: Successful treatment of Stage III neuroblastoma based on prospective biologic staging: A Children's Cancer Group Study. J Clin Oncol 16:1256-1264, 1998
5. Frappaz D, Michon J, Coze C, et al: LMCE3 treatment strategy: Results in 99 consecutively diagnosed stage 4 neuroblastomas in children older than 1 year at diagnosis. J Clin Oncol 18:468-476, 2000
6. Matthay KK, Villablanca JG, Seeger RC, et al: Treatment of high-risk neuroblastoma with intensive chemotherapy, radiotherapy, autologous bone marrow transplantation, and 13-cis-retinoic acid. N Engl J Med 341:1165-1173, 1999
7. De Bernardi B, Nicolas B, Boni L, et al: Disseminated neuroblastoma in children older than one year at diagnosis: Comparable results with three consecutive high-dose protocols adopted by the Italian Co-Operative Group for Neuroblastoma. J Clin Oncol 21:1592-1601, 2003 8. Cheung NK, Heller G: Chemotherapy dose intensity correlates strongly with response, median survival, and median progression-free survival in metastatic neuroblastoma. J Clin Oncol 9:1050-1058, 1991[Abstract] 9. Philip T, Zucker JM, Bernard JL, et al: Improved survival at 2 and 5 years in the LMCE1 unselected group of 72 children with stage IV neuroblastoma older than 1 year of age at diagnosis: Is cure possible in a small subgroup? J Clin Oncol 9:1037-1044, 1991[Abstract] 10. Stram DO, Matthay KK, O'Leary M, et al: Consolidation chemoradiotherapy and autologous bone marrow transplantation versus continued chemotherapy for metastatic neuroblastoma: A report of two concurrent Children's Cancer Group Studies. J Clin Oncol 14:2417-2426, 1996[Abstract] 11. Cohn SL, Moss TJ, Hoover M, et al: Treatment of poor-risk neuroblastoma patients with high-dose chemotherapy and autologous peripheral stem cell rescue. Bone Marrow Transplant 20:543-551, 1997[CrossRef][Medline]
12. Kletzel M, Katzenstein HM, Haut PR, et al: Treatment of high-risk neuroblastoma with triple-tandem high-dose therapy and stem-cell rescue: Results of the Chicago Pilot II Study. J Clin Oncol 20:2284-2292, 2002
13. Grupp SA, Stern JW, Bunin N, et al: Tandem high-dose therapy in rapid sequence for children with high-risk neuroblastoma. J Clin Oncol 18:2567-2575, 2000
14. Brodeur GM, Seeger RC, Schwab M, et al: Amplification of N-myc in untreated human neuroblastomas correlates with advanced disease stage. Science 224:1121-1124, 1984
15. Cohn SL, London WB, Huang D, et al: MYCN expression is not prognostic of adverse outcome in advanced-stage neuroblastoma with nonamplified. MYCN. J Clin Oncol 18:3604-3613, 2000 16. Shimada H, Ambros IM, Dehner LP, et al: The International Neuroblastoma Pathology Classification (the Shimada System). Cancer 86:364-372, 1999[CrossRef][Medline] 17. Look AT, Hayes FA, Shuster JJ, et al: Clinical relevance of tumor cell ploidy and N-myc gene amplification in childhood neuroblastoma: A Pediatric Oncology Group study. J Clin Oncol 9:581-591, 1991[Abstract]
18. Ambros IM, Zellner A, Roald B, et al: Role of ploidy, chromosome 1p, and Schwann cells in the maturation of neuroblastoma. N Engl J Med 334:1505-1511, 1996 19. Gaynon PS, Desai AA, Bostrom BC, et al: Early response to therapy and outcome in childhood acute lymphoblastic leukemia: A review. Cancer 80:1717-1726, 1997[CrossRef][Medline] 20. Davis AM, Bell RS, Goodwin PJ: Prognostic factors in osteosarcoma: A critical review. J Clin Oncol 12:423-431, 1994[Abstract] 21. King SC, Reiman RJ, Prosnitz LR: Prognostic importance of restaging gallium scans following induction chemotherapy for advanced Hodgkin's disease. J Clin Oncol 12:306-311, 1994[Abstract] 22. Parisi MT, Greene MK, Dykes TM, et al: Efficacy of metaiodobenzylguanidine as a scintigraphic agent for the detection of neuroblastoma. Invest Radiol 27:768-773, 1992[CrossRef][Medline] 23. Lastoria S, Maurea S, Caraco C, et al: Iodine-131 metaiodobenzylguanidine scintigraphy for localization of lesions in children with neuroblastoma: Comparison with computed tomography and ultrasonography. Eur J Nucl Med 20:1161-1167, 1993[Medline] 24. Suc A, Lumbroso J, Rubie H, et al: Metastatic neuroblastoma in children older than one year: Prognostic significance of the initial metaiodobenzylguanidine scan and proposal for a scoring system. Cancer 77:805-811, 1996[CrossRef][Medline] 25. Ady N, Zucker JM, Asselain B, et al: A new 123I-MIBG whole body scan scoring methodapplication to the prediction of the response of metastases to induction chemotherapy in stage IV neuroblastoma. Eur J Cancer 31A:256-261, 1995 26. Labreveux de Cervens C, Hartmann O, Bonnin F, et al: What is the prognostic value of osteomedullary uptake on MIBG scan in neuroblastoma patients under one year of age? Med Pediatr Oncol 22:107-114, 1994[Medline]
27. Matthay KK, Edeline V, Lumbroso J, et al: Correlation of early metastatic response by 123I-metaiodobenzylguanidine scintigraphy with overall response and event-free survival in stage IV neuroblastoma. J Clin Oncol 21:2486-2491, 2003 28. Perel Y, Conway J, Kletzel M, et al: Clinical impact and prognostic value of metaiodobenzylguanidine imaging in children with metastatic neuroblastoma. J Pediatr Hematol Oncol 21:13-18, 1999[CrossRef][Medline] 29. George R, London WB, Maris JM, et al: Age as a continuous variable in predicting outcome for neuroblastoma patients with metastatic disease: Impact of tumor biological features. Proc Am Soc Clin Oncol 22:799, 2003 (abstr 3213) 30. Schmidt ML, Lal A, Seeger R, et al: Favorable prognosis for patients age 12-18 months with stage 4 MYCN-nonamplified neuroblastoma. Proc Am Soc Clin Oncol 22:800, 2003 (abstr 3214) 31. Shapiro DN, Valentine MB, Rowe ST, et al: Detection of N-myc gene amplification by fluorescence in situ hybridization. Diagnostic utility for neuroblastoma. Am J Pathol 142:1339-1346, 1993[Abstract]
32. Brodeur GM, Pritchard J, Berthold F, et al: Revisions of the international criteria for neuroblastoma diagnosis, staging, and response to treatment. J Clin Oncol 11:1466-1477, 1993 33. Pan WJ, Haut PR, Olszewski M, et al: Two-day collection and pooling of peripheral blood stem cells with semiautomated density gradient cell separation. J Hematother Stem Cell Res 8:561-564, 1999[CrossRef][Medline] 34. Mock BH, Weiner RE: Simplified solid-state labelling of [123]m-iodobenzylguanidine. Appl Radiat Isot 39:939-942, 1988 35. Kaplan EL, Meier P: Nonparametric estimation from incomplete observations. J Am Stat Assoc 53:457-481, 1958[CrossRef] 36. Frappaz D, Bonneu A, Chauvot P, et al: Metaiodobenzylguanidine assessment of metastatic neuroblastoma: Observer dependency and chemosensitivity evaluation. The SFOP Group. Med Pediatr Oncol 34:237-241, 2000[CrossRef][Medline] 37. Ladenstein R, Philip T, Lasset C, et al: Multivariate analysis of risk factors in stage 4 neuroblastoma patients over the age of one year treated with megatherapy and stem-cell transplantation: A report from the European Bone Marrow Transplantation Solid Tumor Registry. J Clin Oncol 16:953-965, 1998[Abstract] 38. Garaventa A, Bellagamba O, Lo Piccolo MS, et al: 131I-metaiodobenzylguanidine (131I-MIBG) therapy for residual neuroblastoma: A mono-institutional experience with 43 patients. Br J Cancer 81:1378-1384, 1999[CrossRef][Medline] 39. Goldberg SS, DeSantes K, Huberty JP, et al: Engraftment after myeloablative doses of 131I-metaiodobenzylguanidine followed by autologous bone marrow transplantation for treatment of refractory neuroblastoma. Med Pediatr Oncol 30:339-346, 1998[CrossRef][Medline] 40. Reynolds CP, Matthay KK, Villablanca JG, et al: Retinoid therapy of high-risk neuroblastoma. Cancer Lett 197:185-192, 2003[CrossRef][Medline] 41. Ribatti D, Raffaghello L, Marimpietri D, et al: Fenretinide as an anti-angiogenic agent in neuroblastoma. Cancer Lett 197:181-184, 2003[CrossRef][Medline]
42. Beppu K, Jaboine J, Merchant MS, et al: Effect of imatinib mesylate on neuroblastoma tumorigenesis and vascular endothelial growth factor expression. J Natl Cancer Inst 96:46-55, 2004
43. Katzenstein HM, Rademaker AW, Senger C, et al: Effectiveness of the angiogenesis inhibitor TNP-470 in reducing the growth of human neuroblastoma in nude mice inversely correlates with tumor burden. Clin Cancer Res 5:4273-4278, 1999
44. Williams JI, Weitman S, Gonzalez CM, et al: Squalamine treatment of human tumors in nu/nu mice enhances platinum-based chemotherapies. Clin Cancer Res 7:724-733, 2001
45. Cheung NK, Kushner BH, Cheung IY, et al: Anti-G(D2) antibody treatment of minimal residual stage 4 neuroblastoma diagnosed at more than 1 year of age. J Clin Oncol 16:3053-3060, 1998 46. Yu AL, Uttenreuther-Fischer MM, Huang CS, et al: Phase I trial of a human-mouse chimeric anti-disialoganglioside monoclonal antibody ch14.18 in patients with refractory neuroblastoma and osteosarcoma. J Clin Oncol 16:2169-2180, 1998[Abstract]
47. Saylors RL III, Stine KC, Sullivan J, et al: Cyclophosphamide plus topotecan in children with recurrent or refractory solid tumors: A Pediatric Oncology Group phase II study. J Clin Oncol 19:3463-3469, 2001
48. Blaney S, Berg SL, Pratt C, et al: A phase I study of irinotecan in pediatric patients: A pediatric oncology group study. Clin Cancer Res 7:32-37, 2001 49. Nitschke R, Parkhurst J, Sullivan J, et al: Topotecan in pediatric patients with recurrent and progressive solid tumors: A Pediatric Oncology Group phase II study. J Pediatr Hematol Oncol 20:315-318, 1998[CrossRef][Medline] Submitted July 21, 2003; accepted July 16, 2004.
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Copyright © 2004 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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