High-dose chemotherapy in poor-prognosis adult small round-cell tumors: clinical and molecular results from a prospective study.

Purpose: The prognosis of metastatic/high-risk localized small round-cell tumors (SRCTs) treated conventionally is dismal. In this phase II study, we explored a high-dose chemotherapy (HD-CT) approach and analyzed the clinical significance of fusion transcripts detection.

Patients And Methods: From June 1997 to November 1999, 28 SRCT patients (median age, 26 years; 14 peripheral primitive neuroectodermal tumors [pPNETs], seven rhabdomyosarcomas [RMSs], and seven desmoplastic small round-cell tumors [DSRCTs]) received induction chemotherapy with ifosfamide, epirubicin, and vincristine followed by HD-CT. Local treatment (radiotherapy and/or surgery) was performed when possible. Molecular analysis was performed on peripheral-blood and leukapheresis products by reverse-transcriptase polymerase chain reaction.

Results: Overall response (OR) was 65% (18 of 28), with 40% complete response and 25% partial response. According to histology, the OR rate was 86% in pPNET and 43% in both RMS DSRCT. With a median follow-up of 35 months, median overall survival was 16 months and median progression-free survival (PFS) was 10 months. PFS was statistically better in pPNET than other histologic types (P =.0045). No correlation was found between the fusion transcript and clinical outcome during follow-up. Furthermore, transcript detection in leukapheretic products was not of prognostic significance.

Conclusion: Intensive HD-CT seems to enhance the response rate and survival when compared with conventional treatment in poor-prognosis pPNET. The poor results of this treatment in RMS and DSRCT do not support the inclusion of such an approach in these patient subsets. No definitive conclusions can currently be drawn concerning the clinical implications of the detection of fusion transcripts during treatment or follow-up.