Impact of High-Dose-Rate and Low-Dose-Rate Brachytherapy Boost on Toxicity, Functional and Cancer Outcomes in Patients Receiving External Beam Radiation Therapy for Prostate Cancer: A National Population-Based Study

Int J Radiat Oncol Biol Phys. 2021 Apr 1;109(5):1219-1229. doi: 10.1016/j.ijrobp.2020.11.023. Epub 2020 Dec 3.

Abstract

Purpose: External beam radiation therapy (EBRT) with brachytherapy boost reduces cancer recurrence in patients with prostate cancer compared with EBRT monotherapy. However, randomized controlled trials or large-scale observational studies have not compared brachytherapy boost types directly.

Methods and materials: This observational cohort study used linked national cancer registry data, radiation therapy data, administrative hospital data, and mortality records of 54,642 patients with intermediate-risk, high-risk, and locally advanced prostate cancer in England. The records of 11,676 patients were also linked to results from a national patient survey collected at least 18 months after diagnosis. Competing risk regression analyses were used to compare gastrointestinal (GI) toxicity, genitourinary (GU) toxicity, skeletal-related events (SRE), and prostate cancer-specific mortality (PCSM) at 5 years with adjustment for patient and tumor characteristics. Linear regression was used to compare Expanded Prostate Cancer Index Composite 26-item version domain scores (scale, 0-100, with higher scores indicating better function).

Results: Five-year GI toxicity was significantly increased after low-dose-rate brachytherapy boost (LDR-BB) (32.3%) compared with high-dose-rate brachytherapy boost (HDR-BB) (16.7%) or EBRT monotherapy (18.7%). Five-year GU toxicity was significantly increased after both LDR-BB (15.8%) and HDR-BB (16.6%), compared with EBRT monotherapy (10.4%). These toxicity patterns were matched by the mean patient-reported bowel function scores (LDR-BB, 77.3; HDR-BB, 85.8; EBRT monotherapy, 84.4) and the mean patient-reported urinary obstruction/irritation function scores (LDR-BB, 72.2; HDR-BB, 78.9; EBRT monotherapy, 83.8). Five-year incidences of SREs and PCSM were significantly lower after HDR-BB (2.4% and 2.7%, respectively) compared with EBRT monotherapy (2.8% and 3.5%, respectively).

Conclusions: Compared with EBRT monotherapy, LDR-BB has worse GI and GU toxicity and HDR-BB has worse GU toxicity. HDR-BB has a lower incidence of SREs and PCSM than EBRT monotherapy.

Publication types

  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bone and Bones / radiation effects
  • Brachytherapy / adverse effects*
  • Brachytherapy / methods
  • Cohort Studies
  • England
  • Gastrointestinal Tract / radiation effects
  • Humans
  • Linear Models
  • Male
  • Neoplasm Grading
  • Neoplasm Recurrence, Local / prevention & control
  • Prostatic Neoplasms / mortality
  • Prostatic Neoplasms / pathology
  • Prostatic Neoplasms / radiotherapy*
  • Radiotherapy Dosage
  • Re-Irradiation / adverse effects
  • Re-Irradiation / methods
  • Registries / statistics & numerical data
  • Regression Analysis
  • Urogenital System / radiation effects