Pulsed-dose rate brachytherapy for pediatric bladder prostate rhabdomyosarcoma: Compliance and early clinical results

Objective No data are available on the feasibility of pulsed dose rate (PDR) brachytherapy in very young children. Our experience of PDR brachytherapy for bladder prostate (BP) rhabdomyosarcoma (RMS) is reported, with focus on compliance and dosimetric parameters. Materials and methods Treatment parameters and outcome of consecutive BP RMS patients treated in our center were examined. Treatment was carried out as part of a multimodal conservative radio-surgical treatment. Four single leader plastic tubes were implanted under perioperative guidance, encompassing the prostate/bladder neck. Tubes were systematically sutured to the bladder wall. Treatment planning was based on a computed tomography and followed Paris system rules. Continuous hourly pulses of 0.42 Gy were delivered, to a total dose of 60 Gy. Results 32 patients were treated, median age 2.6 years (10 months–12 years). Median duration of each pulse was 8.5 min (3.8–17.4 min). The minimal dose in the most irradiated 1 cm³ of rectum was 44.7 Gy_{α / β =3} (range: 4.1–77.3 Gy_{α / β =3}). Brachytherapy was conducted without significant compliance concern in all but two patients, 24 and 25 months-old, who pulled out plastic tubes before treatment completion. Another child needed re-planning because of slight tube displacement. With median follow-up of 14.4 months (15 days–75 months), all patients were free from any relapse after local treatment. Four grade 3 acute urinary complications were encountered. All long-term side effects were grade 2 or less. Conclusion PDR brachytherapy is feasible in very young patients, and associated with acceptable acute toxicity rates. Longer follow-up is required to ensure that local control and long-term side effects profile are comparable to the results of low dose rate brachytherapy.