Sunday, September 28, 2025

Contouring for Genitourinary Cancer

Faculty

  • Hong Zhang, MD, PhD - Professor of Radiation Oncology, University of Rochester Medical Center,Wilmot Cancer Institute
  • Neil Taunk, MD, MS - Assistant Professor of Radiation Oncology and Radiology, University of Pennsylvania, Abramson Cancer Center

Review the case description and images below.

Case Description

  • Patient: 65-year-old male
  • Initial Diagnosis:
    • PSA prior to surgery: 8.6 
    • Pathologic stage: pT3aN0cM0, Gleason grade group 4
    • surgical margins negative, extraprostatic extension at the bladder neck
  • Postoperative Course:
    • PSA nadir: 0.07 ng/mL
    • PSA progression: Increased to 0.7 ng/ml, doubling time 6 months
  • Restaging Studies:
    • PSMA PET: No evidence of PSMA-avid disease
    • Multiparametric MRI: No evidence of disease
  • Current Management:
    • Initiated on salvage radiation therapy with 6 months of ADT

Question

Which of the displayed sagittal below contours appropriately represents the inferior border of the prostate bed CTV? 

Faculty Follow Up

ANSWER - CTV Option 2

Defining the Inferior Border of Prostate Bed CTV

  • High incidence of recurrence at the vesicourethral anastomosis (VUA)
  • Accurate delineation of the prostate bed clinical target volume (CTV), including the inferior border, is critical to ensure adequate coverage of this high-risk region while respecting normal tissue tolerances 
  • Consensus guidelines vary in how inferior borders are defined

CTV Inferior Border Contour Guidelines

*VUA: vesicourethral anastomosis 
 

MR can reduce inter-observer variability in prostate bed radiotherapy planning
 

  • MR sim or planning MR
  • Identify the last slice on the axial view where urine is visualized, VUA is one slice below this slice
  • Using the sagittal view to confirm the location of VUA

 

  • High incidence of recurrence at the vesicourethral anastomosis (VUA)
  • Accurate delineation of the prostate bed clinical target volume (CTV) is critical to ensure adequate coverage of this high-risk region while respecting normal tissue tolerances
  • Integration of modern imaging, MRI prostate and PSMA PET, for treatment planning


The best way to define the inferior border of CTV

Patient-tailored approach
Using imaging and clinical context to guide individualized adjustments to the inferior border of CTV.