Use of a Biodegradable, Contrast-Filled Rectal Spacer Balloon in Intensity-Modulated Radiotherapy for Intermediate-Risk Prostate Cancer Patients: Dosimetric Gains in the BioPro-RCMI-1505 Study

Igor Latorzeff; Eric Bruguière; Emilie Bogart; Marie-Cécile Le Deley; Eric Lartigau; Delphine Marre; David Pasquier

doi:10.3389/fonc.2021.701998

Use of a Biodegradable, Contrast-Filled Rectal Spacer Balloon in Intensity-Modulated Radiotherapy for Intermediate-Risk Prostate Cancer Patients: Dosimetric Gains in the BioPro-RCMI-1505 Study

Front Oncol. 2021 Aug 26:11:701998. doi: 10.3389/fonc.2021.701998. eCollection 2021.

Authors

Igor Latorzeff¹, Eric Bruguière², Emilie Bogart³, Marie-Cécile Le Deley³, Eric Lartigau^{4

5}, Delphine Marre⁶, David Pasquier^{4

5}

Affiliations

¹ Department of Radiotherapy, Clinique Pasteur, Toulouse, France.
² Department of Imaging, Clinique Pasteur, Toulouse, France.
³ Methodology and Biostatistics Unit, Centre Oscar Lambret, Lille, France.
⁴ Academic Department of Radiation Oncology, Centre Oscar Lambret, Lille, France.
⁵ CRIStAL UMR CNRS 9189, Lille University, Lille, France.
⁶ Department of Physics, Clinique Pasteur, Toulouse, France.

Abstract

Background/purpose: Dose-escalated external beam radiotherapy (RT) is effective in the control of prostate cancer but is associated with a greater incidence of rectal adverse events. We assessed the dosimetric gain and safety profile associated with implantation of a new biodegradable rectal spacer balloon.

Materials/methods: Patients scheduled for image-guided, intensity-modulated RT for intermediate-risk prostate cancer were prospectively included in the French multicenter BioPro-RCMI-1505 study (NCT02478112). We evaluated the dosimetric gain, implantation feasibility, adverse events (AEs), and prostate-cancer-specific quality of life associated with use of the balloon spacer.

Results: After a scheduled review of the initial recruitment target of 50 patients by the study's independent data monitoring committee (IDMC), a total of 24 patients (including 22 with dosimetry data) were included by a single center between November 2016 and May 2018. The interventional radiologist who implanted the balloons considered that 86% of the procedures were easy. 20 of the 24 patients (83.3%) received IMRT and 4 (16.7%) received volumetric modulated arc therapy (78-80 Gy delivered in 39 fractions). The dosimetric gains associated with spacer implantation were highly significant (p<0.001) for most variables. For the rectum, the median (range) relative gain ranged from 15.4% (-9.2-47.5) for D20cc to 91.4% (36.8-100.0) for V70 Gy (%). 15 patients (62%) experienced an acute grade 1 AE, 8 (33%) experienced a late grade 1 AE, 1 (4.2%) experienced an acute grade 2 AE, and 3 experienced a late grade 2 AE. No grade 3 AEs were reported. Quality of life was good at baseline (except for sexual activity) and did not markedly worsen during RT and up to 24 months afterwards.

Conclusion: The use of a biodegradable rectal spacer balloon is safe, effective and associated with dosimetric gains in modern RT for intermediate-risk prostate cancer.

Keywords: dosimetric analyses; intensity-modulated radiotherapy; intermediate risk group; organs at risk; prospective study; prostate cancer; quality of life; spacer with biodegradable contrast-filled rectal balloon.