{
  "abstract": "Background and purpose: The introduction of volumetric modulated arc therapy (VMAT) has enabled dosimetric improvements during prostate bed (PB) radiotherapy; however, the planning target volume (PTV) margins remain substantially greater than for prostate radiotherapy. New approaches are required to further optimise rectal dose and minimise target and organ motion. ProSpare®, a self-inserted rectal obturator designed to facilitate daily image guidance, may enhance radiotherapy accuracy and reduce treatment-related morbidity.\n\nMaterials and methods: Patients scheduled to receive adjuvant or salvage PB radiotherapy after radical prostatectomy were randomised to either standard-of-care (SOC) PB-IMRT using centre-standard PTV margins and verification protocol (SOC) or PB-IMRT with daily ProSpare®-guided radiotherapy using a reduced 5-mm posterior margin. Dose and fractionation schedules were selected by each centre according to protocol recommendations. The primary endpoint is patient-reported EPIC bowel function and bother at 2 years. Secondary endpoints include acute Radiation Therapy Oncology Group (RTOG) and CTCAE toxicity, patient-reported outcomes, device tolerability, and anorectal dosimetry. We report the results from the prespecified analysis of these secondary endpoints.\n\nResults: Between 2017 and 2023, 162 patients were recruited; 158 began radiotherapy and were evaluable at 18 weeks. Acute toxicity data were available for 146 patients (SOC 76/81, ProSpare 70/77). Compared with SOC, ProSpare® was associated with lower 18-week RTOG ≥grade 1 gastrointestinal (GI) and genitourinary (GU) toxicity (39% vs. 31% and 37% vs. 29%, respectively). The incidence of worst CTCAE grade 2 GI and GU toxicity was <6%. Of 51 responders, 50 found ProSpare® tolerable and would recommend its use. Use of ProSpare® resulted in consistently lower ano-rectal dose–volume parameters.\n\nConclusion: ProSpare®-guided prostate bed radiotherapy (PBRT) resulted in lower acute RTOG bowel toxicity at all time points. Patient-reported tolerability was very favourable. Use of ProSpare® improved rectal and anal canal dosimetry.\n\nClinical Trial Registration: ClinicalTrials.gov, identifier NCT02978014.",
  "abstract_shown": true,
  "affiliations": [
    "The Institute of Cancer Research, London, United Kingdom",
    "Royal Marsden Hospital, London, United Kingdom",
    "Ipswich Hospital, Ipswich, United Kingdom",
    "Royal Surrey NHS Foundation Trust, Guildford, United Kingdom",
    "University College Hospital, London, United Kingdom",
    "Musgrove Park Hospital, Taunton, United Kingdom",
    "Mount Vernon Cancer Centre, Northwood, United Kingdom",
    "Royal Free London NHS Foundation Trust, London, United Kingdom",
    "Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich, United Kingdom",
    "Addenbrooke’s Hospital, Cambridge, United Kingdom",
    "Ipswich Hospital NHS Trust, Ipswich, United Kingdom"
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 23,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Sarah Stewart"
    },
    {
      "affs": [
        1
      ],
      "name": "Karen Thomas"
    },
    {
      "affs": [
        1
      ],
      "name": "Jenni Parmar"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Alison Claire Tree"
    },
    {
      "affs": [
        1
      ],
      "name": "Chris Parker"
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    {
      "affs": [
        0,
        1
      ],
      "name": "Helen McNair"
    },
    {
      "affs": [
        1
      ],
      "name": "Sophie Alexander"
    },
    {
      "affs": [
        1
      ],
      "name": "Julia Henderson"
    },
    {
      "affs": [
        1
      ],
      "name": "James Talbot"
    },
    {
      "affs": [
        2
      ],
      "name": "Christopher Scrase"
    },
    {
      "affs": [
        3
      ],
      "name": "Chee Goh"
    },
    {
      "affs": [
        4
      ],
      "name": "Reena Davda"
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    {
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        5
      ],
      "name": "Emma Gray"
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    {
      "affs": [
        6
      ],
      "name": "Peter Hoskin"
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    {
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        7
      ],
      "name": "Sarah Needleman"
    },
    {
      "affs": [
        8
      ],
      "name": "Jenny Nobes"
    },
    {
      "affs": [
        9
      ],
      "name": "Kamalram Thippu Jayaprakash"
    },
    {
      "affs": [
        9
      ],
      "name": "Yvonne Rimmer"
    },
    {
      "affs": [
        10
      ],
      "name": "Ranachandran Venkitaraman"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Anna Wilkins"
    },
    {
      "affs": [
        1
      ],
      "name": "Vincent Khoo"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Julia Murray"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "David Paul Dearnaley"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/ffr6r7k1vej41.bib",
  "cited_by": 0,
  "doi": "10.3389/fonc.2026.1758462",
  "fulltext_url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC13696223/",
  "id": "ffr6r7k1vej41",
  "issns": [
    "2234-943X"
  ],
  "landing_url": "https://doi.org/10.3389/fonc.2026.1758462",
  "language": "en",
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
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      "3108|Advanced Radiotherapy Techniques"
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  "pdf_url": "https://europepmc.org/articles/PMC13696223?pdf=render",
  "pmcid": "PMC13696223",
  "pmid": "42935520",
  "published": "2026-10-12",
  "publisher": "Frontiers Media SA",
  "ris": "https://research.draconitic.com/paper/ffr6r7k1vej41.ris",
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      "field": "physics",
      "origin": "openalex:3108|Advanced Radiotherapy Techniques",
      "subfield": "applied-instrumentation"
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  ],
  "title": "Preliminary evaluation of ProSpare®, a rectal obturator for prostate bed radiotherapy within the randomised multicentre POPS trial (NCT02978014)",
  "title_text": "Preliminary evaluation of ProSpare®, a rectal obturator for prostate bed radiotherapy within the randomised multicentre POPS trial (NCT02978014)",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:33:36Z",
  "url": "https://research.draconitic.com/paper/ffr6r7k1vej41",
  "venue": "Frontiers in Oncology",
  "versions": []
}