International Consensus Guidelines for Adjuvant Radiation Therapy for Bladder Cancer After Radical Cystectomy: Update From an IBIS Workgroup

Flor Verghote; Paul Sargos; John P Christodouleas; Vedang Murthy; Brian C Baumann; Piet Dirix; Charlien Berghen; Leen Paelinck; Tom Vercauteren; Valérie Fonteyne

doi:10.1016/j.prro.2022.05.014

International Consensus Guidelines for Adjuvant Radiation Therapy for Bladder Cancer After Radical Cystectomy: Update From an IBIS Workgroup

Pract Radiat Oncol. 2022 Nov-Dec;12(6):524-532. doi: 10.1016/j.prro.2022.05.014. Epub 2022 Jun 9.

Authors

Affiliations

¹ Department of Radiation Oncology, Ghent University Hospital, Ghent, Belgium; Department of Human Structure and Repair, Ghent University, Ghent, Belgium. Electronic address: [email protected].
² Department of Radiation Therapy, Institut Bergonié, Bordeaux, France.
³ Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania.
⁴ Department of Radiation Oncology, ACTREC, Tata Memorial Center, HBNI, Mumbai, India.
⁵ Department of Radiation Oncology, Siteman Cancer Center, Washington University School of Medicine, St Louis, Missouri.
⁶ Department of Radiation-Oncology, Iridium Network, Antwerp, Belgium.
⁷ Department of Radiation-Oncology, University Hospitals Leuven, Leuven, Belgium.
⁸ Department of Radiation Oncology, Ghent University Hospital, Ghent, Belgium.
⁹ Department of Radiation Oncology, Ghent University Hospital, Ghent, Belgium; Department of Human Structure and Repair, Ghent University, Ghent, Belgium.

PMID: 35691550
DOI: 10.1016/j.prro.2022.05.014

Abstract

Purpose: In 2016, international consensus clinical target volume (CTV) guidelines for adjuvant radiation treatment after radical cystectomy in patients with muscle-invasive bladder cancer with high risk for locoregional failure (LRF) were published. A subsequent external validation study recommended several CTV optimizations (CTV-OPT). This study aimed to update international consensus guidelines based on new clinical experiences.

Methods and materials: Phase 1 (delineation interobserver variability): Four observers delineated the CTV of 9 patients post radical cystectomy, as in clinical practice. Interobserver agreement in contouring was evaluated using volume- and κ-statistics. Phase 2 (pattern of failure analysis): Among a prospective cohort of 72 patients treated with adjuvant radiation treatment, 11 developed LRF (10 available for review). LRFs were mapped in predefined pelvic subsites (ie, common, external and internal iliac, obturator and presacral node regions, and cystectomy bed), and their distance to CTV-OPT was measured. The actual delivered dose at each relapse site was calculated. Phase 3 (review CTV): Based on the results of phase 1 and 2, 5 senior radiation-oncologists (International Bladder Investigator Society) reviewed the published CTV borders and provided an update when indicated.

Results: Phase 1: The mean overall κ-value was 0.66 (range, 0.60-0.70), indicating substantial overall agreement per Landis-Koch criteria. Specific κ-values per area indicated for the common iliac and obturator node regions only slight and moderate variability, respectively. Phase 2: Thirteen out of 16 LRFs centers were not included in the CTV-OPT. Ten LRF sites received a median dose <45 Gy, of which 6 were located in the cystectomy bed that was not included in the CTV because of negative radical cystectomy margins. Phase 3: Key recommendations by the panel were to include the entire common iliac node region and the cystectomy bed regardless of surgical margin status and a reaffirmation to not crop the CTV out of bowel.

Conclusions: International consensus guidelines were updated.

MeSH terms

Cystectomy* / methods
Humans
Margins of Excision
Prospective Studies
Radiotherapy, Adjuvant / methods
Urinary Bladder
Urinary Bladder Neoplasms* / radiotherapy
Urinary Bladder Neoplasms* / surgery