Local therapy for rhabdomyosarcoma of the bladder and/or prostate without nodal or metastatic spread during the European paediatric Soft tissue sarcoma Study Group (EpSSG) RMS2005 study

<h2>Abstract</h2><h3>Background:</h3> During the EpSSG RMS2005 trial, organ-sparing surgery (OSS) with brachytherapy (BT) became the local therapy (LT) of choice for selected patients with bladder-prostate rhabdomyosarcoma (BP-RMS). We compare this LT technique with surgical resection and/or external-beam radiotherapy. <h3>Methods:</h3> Patients with BP-RMS without nodal or metastatic spread enrolled in RMS2005 were categorized by their LT, differentiating OSS from organ-depleting surgery (ODS) and BT from external-beam radiotherapy (EBRT). Progressive disease, relapse or death were considered events for progression-free survival (PFS) and all deaths for overall survival (OS). <h3>Results:</h3> The cohort comprised 176 patients, aged 10days-21.8years (median 2.5years). Median follow-up was 6.5years (22months-12.5years): 5year-PFS was 80.3% (95%CI:73.6-85.5%); 5year-OS was 90.7% (95%CI:85.3-94.2%). Patients selected for surgery alone or BT with/without OSS (BT+/-OSS) differed significantly in age, tumour size and location from those offered EBRT alone or any other surgery and radiotherapy. Nevertheless, 5year-PFS was similar for the LT groups. However, 5year-OS differed significantly, being highest in patients suitable for surgery alone (100%; by ODS in 55%) or BT+/-OSS (98.1%; 95%CI:87.4-99.7%). Patients with local tumour progression/relapse after EBRT failed salvage: 5year-OS was 81.8% (95%CI:58.5-92.8%) for EBRT alone and 85.3% (95%CI:71.6-92.7%) for surgery and radiotherapy. Postponing LT until after chemotherapy cycle 7 did not significantly impact 5year-PFS or OS. <h3>Conclusions:</h3> The risk of events was similar for different LT modalities; poor salvage after EBRT significantly reduced 5year-OS. Although not feasible for all, BT+/-OSS offers an excellent prospect of cure, the best chance of organ retention while avoiding EBRT, and may be delayed for chemotherapy responsive tumours.