Detection of failure patterns using advanced imaging in patients with biochemical recurrence following low-dose-rate brachytherapy for prostate cancer

Brachytherapy. 2022 Jul-Aug;21(4):442-450. doi: 10.1016/j.brachy.2022.03.009. Epub 2022 May 4.

Abstract

Purpose/objective(s): This study describes the pattern of failure in patients with biochemical (BCR) recurrence after low-dose-rate (LDR) brachytherapy as a component of definitive treatment for prostate cancer.

Methods: Patients with BCR after LDR brachytherapy ± external beam radiation therapy (EBRT) were enrolled on prospective IRB approved advanced imaging protocols. Patients underwent 3T multiparametric MRI (mpMRI); a subset underwent prostate specific membrane antigen (PSMA)-based PET/CT. Pathologic confirmation was obtained unless contraindicated.

Results: Between January 2011 and April 2021, 51 patients with BCR after brachytherapy (n = 36) or brachytherapy + EBRT (n = 15) underwent mpMRI and were included in this analysis. Of 38 patients with available dosimetry, only two had D90<90%. The prostate and seminal vesicles were a site of failure in 66.7% (n = 34) and 39.2% (n = 20), respectively. PET/CT (n = 32 patients) more often identified lesions pelvic lymph nodes (50%; n = 16) and distant metastases (18.8%; n = 6), than mpMRI. Isolated nodal disease (9.8%; n = 5) and distant metastases (n = 1) without local recurrence were uncommon. Recurrence within the prostate was located in the transition zone in 48.5%, central or midline in 45.5%, and anterior in 36.4% of patients.

Conclusion: In this cohort of patients with BCR after LDR brachytherapy ± EBRT, the predominant recurrence pattern was local (prostate ± seminal vesicles) with frequent occurrence in the anterior prostate and transition zone. mpMRI and PSMA PET/CT provided complementary information to localize sites of recurrence, with PSMA PET/CT often confirming mpMRI findings and identifying occult nodal or distant metastases.

Keywords: Low-dose-rate brachytherapy; MRI; PSMA; Prostate cancer; Recurrence.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Brachytherapy* / methods
  • Humans
  • Male
  • Neoplasm Recurrence, Local / diagnostic imaging
  • Neoplasm Recurrence, Local / radiotherapy
  • Positron Emission Tomography Computed Tomography / methods
  • Prospective Studies
  • Prostate-Specific Antigen
  • Prostatic Neoplasms* / diagnostic imaging
  • Prostatic Neoplasms* / pathology
  • Prostatic Neoplasms* / radiotherapy

Substances

  • Prostate-Specific Antigen