PSMA Scan Results." Temporary?" Sigh of Relief

After 7 years post surgery my PSA started to move up and down then the last few times started an upward trend with a doubling time of around 15 months. It got to 0.504 and I decided to do the PSMA scan, knowing that it would probably be in the 50-60% range of picking anything up. Well, it didn't pick anything up. I guess I could have waited til closer to 1. for a higher percentage.
Maybe I'm just a little paranoid but being a pT3a is in the back of my mind. I will monitor it and if it gets up later to 0.8 or 0.9, I'll try to schedule another one. Sound like a plan? Too bad I don't see more helpful info or proven cases of benign tissue. Little odd too that I'm sure my path report said pT3a and it says pT3N0 on the scan results.

PET/CT PSMA VERTEX TO THIGH

Results
Impression
No perceivable PSMA avid local recurrence or metastatic disease to explain the early biochemical recurrence. Please note that PSMA PET/CT has a reported diagnostic sensitivity of ~60% for PSMA level <0.5 ng/ml which increases to ~ 80% for PSA values >1 ng/ml, hence consider a repeat PSMA PET/CT if there is continued rise.

CRITICAL RESULT:
No.

COMMUNICATION:
Per this written report.

By electronically signing this report, I, the attending physician, attest that I have personally reviewed the images/data for the above examination(s) and agree with the final edited report.

Drafted by Dillon Hickman, MD on 3/29/2024 8:20 AM
Final report signed by Harit Kapoor, MD on 3/29/2024 9:53 AM
Narrative
CLINICAL INDICATION:
59 year-old male with history of pT3N0 GrGp 2 prostate cancer, status post robotic-assisted laparoscopic prostatectomy in 2011, presenting for evaluation for treatment planning. PSA levels: 0.45 on 11/2023, 0.375 on 7/2023.

TECHNIQUE:
Radiopharmaceutical: 8.754 mCi of F-18 piflufolastat (PSMA, Pylarify) administered intravenously at right antecubital fossa at 3:16 PM.
Incubation interval: 52 minutes.
Oral contrast: Not applicable.
Positioning: Arms raised.
PET/CT scanner: Siemens Biograph 40 mCT.
PET/CT acquisition: Vertex-to-mid-thighs.
Standardized uptake value (SUV): Corrected for body weight only.
CT: Low-dose, non-breath-hold, without intravenous contrast.
TOTAL DLP (Dose Length Product): 633.12 mGy.cm.

COMPARISON/CORRELATION:
Axumin (F-18 fluciclovine) PET/CT 2/11/2021. No correlative imaging.

FINDINGS:
Technical quality: Diagnostic.

Measurements: Unless otherwise specified, all SUVs refer to maximum value in the target (mSUV).
CT linear measurements performed on axial images.

Head and Neck:
No suspicious focal PSMA-avid uptake.

No obvious space-occupying brain parenchymal masses.
Unremarkable thyroid.
No cervical or supraclavicular adenopathy.

Chest:
No suspicious focal PSMA-avid uptake.

No suspicious sizable pulmonary nodules on this low-dose nonbreath-hold acquisition.
No thoracic adenopathy by CT size criteria.
Normal caliber cardiovascular structures. Mild coronary artery calcifications.
No pericardial or pleural effusion.

Abdomen and Pelvis:
No suspicious focal PSMA-avid uptake.

Specifically, no discrete suspicious focal PSA may avid uptake within the prostatectomy bed. Please note that intense activity within the excreted urine decrease the sensitivity for low volume disease near the vesicourethral anastomosis.

No suspicious PSMA avid abdominopelvic adenopathy.

No discrete suspicious solid organ focal lesions on this noncontrast exam.
Normal caliber hollow viscera. Cholelithiasis without signs of acute cholecystitis.
No evidence of perienteric inflammation or suspicious sizable mesenteric/peritoneal masses.
No ascites.

Skeleton and Soft Tissues:
No suspicious focal PSMA avid uptake. Specifically, no suspicious PSMA avid or clearly aggressive lytic/blastic osseous metastases.

Mild to moderate multilevel spondylosis. No clearly aggressive body wall soft tissue masses.

As your report points out, at PSAs around 0.5, the chances of finding existing lesions have just crossed over the 50% line. One approach would be to presume that recurrence is present and it's more likely in the fossa than metastatic--and irradiate there now rather than waiting for a future positive scan. I would discuss this with my docs. If there is local recurrence, you don't want to give it lots of time to progress and become metastatic. However, it's also true that not all men with BCR (biochemical recurrence or a PSA of at least 0.2 and rising without any lesions detected) go on to clinical recurrence (lesions detected)--that's the flip side of the coin to weigh.

I wouldn't read much into the scan having just "pT3" and not "pT3a." I think they are just not distinguishing the a's (EPE and/or bladder-neck invasion) from the b's (SVI, with or without EPE). The bottom line is that the cancer wasn't prostate-confined at the time of surgery. The "N0" as you know, is just incorporating the negativity of the lymph nodes examined into the staging designation.

Djin

Kwoo, as G3 is known not to metastasize, only G4 and G5 would be the culprits. Unfortunately, no one knows for sure exactly what all Gleason they actually have at diagnosis, just what is found by biopsy or surgical pathology that can be tested. You had G4 identified in the biopsy, so that would be the assumed culprit for Mets. And after a period of time the PCa can continue to mutate to the point that it can no longer measured by Gleason. When Mets are biopsied they are usually not studied for Gleason, but are studied for other factors that can determine how aggressive and how resistant to treatment they might be. Neuroendicrine and small cell are examples. These are rarely found at initial biopsy, but are often found when the cancer becomes significantly advanced.

Regarding PSA, it generally rises with Mets, but there is no technical threshold to determine whether there are Mets. Higher Gleason generally expresses less PSA and some PCa mutates to the point that it no longer expresses any PSA. On the forum we have seen men with very low PSA that had obvious Mets and we have seen men with PSA as high as 35-50 that still didn’t have observable Mets. So it is very individual, but generally, continuously rising PSA signals growing PCa that will eventually be found somewhere as metastasis.

Kwoo, even though the PSMA was clean there is obviously something going on. Have you discussed the situation thoroughly with a RO? Some might suggest getting radiation to the prostate now rather than waiting to see if the cancer has spread?

Jim