#0612

Assessing Outcome of Radiotherapy with Concurrent Androgen Deprivation Therapy in Biochemical Recurrence After Prostatectomy Patients Using F-18-PSMA-1007 PET

Y. Huang¹, E. Huang², T. Wei³, W. Huang³, Y. Chang³, H. Chung³, T. Lin³, C. Lin³, T. Huang³, W. Chen³

¹Taipei Veterans General Hosptial, Taiwan
²Taipei Veterans General Hosptial, Taipei, Taiwan
³Taipei Veterans General Hosptial, Urology, Taipei, Taiwan

Introduction:

Biochemical recurrence (BCR) in post-prostatectomy prostate cancer patients poses a significant clinical challenge, as it is often difficult to detect recurrent lesions using conventional imaging techniques such as CT or MRI. Over the past few years, the use of PSMA PET has emerged as a novel diagnostic tool for identifying BCR. By utilizing F-18-PSMA-1007 PET, our institute has aimed to improve detection rates and better inform treatment strategies. For these patients, specific recurrent lesion was found and we can use radiotherapy as salvage treatment. However, the role of salvage radiotherapy (RT) with concurrent androgen deprivation therapy (ADT) in BCR patients remains less explored.

Material and methods:

We conducted a retrospective review involving 67 post-prostatectomy prostate cancer patients who experienced BCR or persistent prostate-specific antigen (PSA) from 2021 to 2022. All patients underwent conventional MRI and F-18-PSMA-1007 PET/MR scans to identify suspected recurrent lesions. Among them, 13 patients received salvage RT only, forming the RT group. Another 54 patients received salvage RT with concurrent ADT, forming the RT + ADT group. We collected data from pathological reports of prostatectomy, including grade group, T stage, N stage, and surgical margin status. Additionally, we gathered data on the time from prostatectomy to BCR, and progression-free survival (PFS), defined as the absence of new recurrent lesions or PSA elevation after treatment using Kaplan Meier survival analysis.

Results:

The mean ages in the RT group and the RT + ADT group were 71.62 and 69.17 years, respectively, with a mean follow-up time of 42.62 and 37.56 months. No mortality was observed during the follow-up period. Significant differences were found between the two groups in terms of initial PSA (p<0.001), PSA doubling time (PSADT) (p=0.009), PSA at PSMA PET (p=0.005), and EAU (European Association of Urology) BCR risk group (p=0.002). In the RT group, progression-free survival (PFS) rates were 100% at 1 year, 100% at 2 years, and 91.7% at 3 years. In the RT + ADT group, the PFS rates were 98.1% at 1 year, 94.4% at 2 years, and 90.9% at 3 years. There was no significant difference in PFS between the two groups (p=0.954).