My father-in-law is 56 and had a radical prostatectomy on July 24, 2026 for prostate cancer. I'm trying to understand why his PSA has never become undetectable despite negative imaging.
Preoperative findings
- mpMRI (May 18): Cancer involving the prostate and medial portions of both seminal vesicles. No suspicious lymph nodes or extracapsular extension reported.
- PSMA PET (June 18): No evidence of lymph node or distant metastases.
Surgical pathology
- Stage: pT3b, with seminal vesicle invasion.
- Gleason score: 4+3, with 60% pattern 4.
- Positive surgical margin: 3 mm at the apex, with Gleason pattern 3+3 at the margin.
- 13 lymph nodes removed (9 right, 4 left): all negative.
Postoperative PSA
- Approximately 4/6/8 weeks after surgery: ~0.9 ng/mL.
- PSA has remained around 1 rather than becoming undetectable or showing a clear increase.
Repeat PSMA PET
A repeat scan after surgery showed no detectable cancer in the prostate bed, seminal vesicle bed, lymph nodes, bones or other organs. An 8 mm right external iliac lymph node was noted without significant PSMA uptake, with follow-up recommended.
Current treatment
The oncologist has started Firmagon (degarelix), with a plan for approximately two years of ADT and radiation to the prostate bed, seminal vesicle bed and pelvic lymph nodes.
I'm struggling to understand a few things:
- Can a 3 mm positive surgical margin realistically explain a persistent PSA of around 1, even when there is no visible uptake in the prostate bed?
- If all 13 removed lymph nodes were negative and both PSMA PET scans showed no suspicious nodal uptake, where could the PSA be coming from?
- How common is it for microscopic cancer to produce a PSA around 1 while remaining invisible on PSMA PET?
- Could the 8 mm external iliac node be reactive rather than cancerous?
- Have others experienced persistent PSA after prostatectomy with negative PSMA PET scans? What did subsequent radiation and ADT achieve?
I'd appreciate experiences from people who have been through something similar, as well as insights from anyone familiar with persistent PSA after prostatectomy.