2. UroToday Home
  3. Conference Highlights
  4. ASCO GU 2025
  5. ASCO GU 2025 Prostate Cancer

ASCO GU 2025

ASCO GU 2025: Five-Year Follow-up of Prostate Specific Membrane Antigen PET/CT-Guided Salvage Radiotherapy Following Radical Prostatectomy: A Single Center Retrospective Analysis

(UroToday.com) The 2025 American Society of Clinical Oncology Genitourinary (ASCO GU) cancers symposium held in San Francisco, CA between February 13th and 15th 2025, was host to the Poster Session A: Prostate Cancer. Dr. John Nikitas presented Abstract 336: Five-year follow-up of prostate specific membrane antigen PET/CT-guided salvage radiotherapy following radical prostatectomy: A single center retrospective analysis.

Salvage radiation therapy (sRT) is the standard of care for biochemically recurrent prostate cancer following radical prostatectomy (RP). In this setting, prostate-specific membrane antigen (PSMA) PET/CT offers superior sensitivity and specificity in detecting recurrent disease, even at low prostate-specific antigen (PSA) levels. PSMA PET/CT can also aid in target volume delineation for sRT. The objective of this study was to evaluate the impact of PSMA PET/CT guidance on long-term clinical outcomes following sRT.

The investigators retrospectively screened five prospective PSMA PET/CT studies conducted at the University of California, Los Angeles, between 2016 and 2021. They included patients who had previously undergone radical prostatectomy (RP), were restaged with PSMA PET/CT at their first biochemical recurrence (PSA >0.2 ng/mL), received sRT, and had at least 24 months of follow-up from the start of sRT.

The endpoints of the study were progression-free survival (PFS), freedom from distant progression, and overall survival (OS). These endpoints were assessed from the start of sRT using the Kaplan-Meier method. Moreover, they used Cox regression analysis to calculate adjusted hazard ratios for PFS, adjusting for androgen deprivation therapy (ADT), age, pre-sRT PSA level, and the use of whole-pelvis radiotherapy (WPRT).

A total of 113 patients who received sRT met the inclusion criteria. The median PSA at the time of PSMA PET/CT was 0.4 ng/mL (IQR, 0.3–1.0), and the median time from RP to sRT was 19.9 months (IQR, 5.6–51.8).
On PSMA PET/CT, disease recurrence patterns were as follows: 19 patients (17%) had local recurrence, 35 (31%) had nodal recurrence (miN1/M1a), 13 (12%) had distant metastases (M1b-c), and 46 (41%) had no visible disease.
On PSMA PET/CT, disease recurrence patterns were as follows: 19 patients (17%) had local recurrence, 35 (31%) had nodal recurrence (miN1/M1a), 13 (12%) had distant metastases (M1b-c), and 46 (41%) had no visible disease.
Within this cohort, 67% received ADT, and 62% underwent WPRT. The radiotherapy targets are reported below:Within this cohort, 67% received ADT, and 62% underwent WPRT. The radiotherapy targets are reported below:
The median follow-up was 59.4 months, during which 57 patients (50%) experienced disease progression. The median PFS was 49.2 months (95% CI, 24.1–74.3), and the median freedom from distant progression was 76.4 months (95% CI, 62.9–89.9). Median OS was not reached; however, the five-year OS rate was 97.1%.The median follow-up was 59.4 months, during which 57 patients (50%) experienced disease progression. The median PFS was 49.2 months (95% CI, 24.1–74.3), and the median freedom from distant progression was 76.4 months (95% CI, 62.9–89.9). Median OS was not reached; however, the five-year OS rate was 97.1%.
Patients with no visible disease (miT0N0M0) had the most favorable PFS (aHR relative to the M1b-c cohort, 0.25), followed by those with local recurrence (TrN0M0) and N1/M1a disease (aHR relative to M1b-c, 0.39 for both).
Patients with no visible disease (miT0N0M0) had the most favorable PFS (aHR relative to the M1b-c cohort, 0.25), followed by those with local recurrence (TrN0M0) and N1/M1a disease (aHR relative to M1b-c, 0.39 for both).
Pre-radiotherapy PSA was not associated with PFS (aHR, 1.0; p=0.98). WPRT was significantly associated with improved PFS in TrN0M0 patients (aHR, 0.12; p=0.035) but not in T0N0M0 patients (aHR, 0.87; p=0.8).

Notably, among T0 N1/M1 patients, prostate bed irradiation was significantly associated with improved PFS (aHR, 0.25; p=0.005).

ADT was not associated with improved PFS in T0N0M0 or TrN0M0 patients (p>0.05 for both). However, among N1/M1 patients, ADT was significantly associated with improved PFS (aHR, 0.37; p=0.02).

Dr. Nikitas concluded his poster with the following key takeaways:

  • PSMA PET/CT-guided salvage radiotherapy was associated with favorable long-term clinical outcomes in this retrospective UCLA cohort.
  • Exploratory analyses suggest a benefit of WPRT in patients with prostate bed recurrence or local recurrence (miTrN0M0) detected on PSMA PET/CT.
  • ADT was associated with improved PFS in patients with miN1 or miM1 disease on PSMA PET/CT but not among miT0N0M0 or miTrN0M0
  • Further prospective studies are needed to validate these findings.

Presented by: John Nikitas, MD, Radiation Oncology PGY5 at University of California Los Angeles (UCLA), Los Angeles, CA.

Written by: Julian Chavarriaga, MD – Urologic Oncologist at Cancer Treatment and Research Center (CTIC) via Society of Urologic Oncology (SUO) Fellow at The University of Toronto. @chavarriagaj on Twitter during the 2025 Genitourinary (GU) American Society of Clinical Oncology (ASCO) Annual Meeting, San Francisco, CA, Thurs, Feb 13 – Sat, Feb 15, 2025.