Delayed Genitourinary Toxicity Experienced by Minority of Patients Following Stereotactic Prostate Radiation Therapy

Strategic Insights -

Researchers from Liverpool and Macarthur Cancer Therapy Centres have published a study investigating the relationship between radiation dose to the bladder and urethra and genitourinary (GU) toxicity grade 2 in patients treated with stereotactic body radiation therapy (SBRT) for prostate cancer. The study found that delayed GU toxicity is experienced by 15% to 30% of patients, with 19.5% experiencing grade 2 GU toxicity more than 6 months after SBRT. The study suggests that additional bladder constraints, including dose-volume histograms (DVH) for the bladder, may be necessary to minimize urinary toxicity.

Key Takeaways:

  • The study highlights the need for careful dosimetry planning to minimize urinary toxicity in patients undergoing SBRT for prostate cancer.
  • Delayed GU toxicity is a significant concern in patients treated with SBRT, with 15% to 30% experiencing grade 2 GU toxicity more than 6 months after treatment.
  • Prostatic urethral length, urethral planning organ at risk volume (PRV) volume, bladder dose-volume histograms, and prior transurethral resection of the prostate (TURP) were predictive of GU toxicity.
  • The study suggests that additional bladder constraints, including D10 cc, may be necessary to minimize urinary toxicity.
  • The research concluded that prostate SBRT delivered as a virtual high-dose-rate boost is well-tolerated overall, but delayed GU toxicity is experienced by a significant minority of patients.

Statistics:

  • 15% to 30% of patients experience delayed GU toxicity following SBRT for prostate cancer.
  • 19.5% of patients experience grade 2 GU toxicity more than 6 months after SBRT.
  • Prostatic urethral length: P = 0.001 Predictive of GU toxicity
  • Urethral PRV volume: P = 0.02 Predictive of GU toxicity
  • Bladder D2 cc: P = 0.01 Predictive of GU toxicity
  • Bladder D5 cc: P = 0.01 Predictive of GU toxicity
  • Bladder D10 cc: P = 0.01 Predictive of GU toxicity
  • Bladder V8: P = 0.01 Predictive of GU toxicity

Sources:

  • Dosimetric Clues to Addressing Urinary Toxicity Following Stereotactic Prostate Radiation Therapy. Advances in Radiation Oncology, 2025,10(9):101850.
  • Researchers from Liverpool and Macarthur Cancer Therapy Centres Report on Findings in Cancer (Dosimetric Clues to Addressing Urinary Toxicity Following Stereotactic Prostate Radiation Therapy). Health & Medicine Week. September 12, 2025; p 6013.