First time doctor orders an FDG scan Is it a bad sign?

Sometimes they initially order a dual Pet using FDG along with Pylarify (PSMA) Some cancers don't produce sufficient PSA. It is more likely a good sign that the PSMA isn't signaling and another good sign that you are getting thorough care. FDG tracks sugar consumption which can be evidence of cancer that is not producing PSA.

The FDG scan can find Neuroendocrine prostate cancer.

In more advanced cases, it cannot be seen in the PSMA PET scan.

The FDG scan looks for glucose when it sees it, it lights up. Normal prostate cancer doesn’t Consume it.

They may be looking for cancer cells that don't express PSMA. My husband had C-11 choline PET scans once during and once after he finished Pluvicto at Mayo Rochester. If your facility doesn't do choline scans, then the FDG scan may be part of a similar protocol and a routine scan after several infusions.

@lag
Well, you can use a choline Scan to find Neuroendocrine cancer it is not designed for finding it. You really need to do the FDG scan..

@jeffmarc The original poster seemed to be worrying about why the doctor ordered an FDG scan. I was trying to offer an explanation. I didn’t mean to comment on looking for neuroendocrine cancer. Sorry for any confusion.

@lag
Since the FDG scan is not capable of seeing prostate cancer, since it does not consume glucose, The only reason I can imagine they would want that scan is for neuroendocrine cancer.

@jeffmarc I understand now. I didn’t know the FDG couldn’t detect prostate cancer. Sorry to muddy the waters.

Many cancers do feed on glucose - brain, lung, lymphomas, just to name a few. But, all cancers aren’t the same.
Those cancers are known to gobble up glucose (sugar), which is why the F18-FDG (Fluoro-2-Deoxyglucose) PET/CT scan worked so well detecting brain cancers, but was totally worthless detecting early/mid-stage prostate cancer. Prostate cancer feeds on testosterone.

As prostate cancer becomes more aggressive, metastasizes, or develops castration resistance, then prostate cancers find an alternative food source (and the F18-FDG PET/CT scan better detects prostate cancers).

Drs Scholz and Moyad touched on this topic at a 2019 PCRI conference: https://youtu.be/-PyqazlkpCE

It’s not a bad sign; they simply understand the nature of the prostate cancer they’re dealing with and are going after it appropriately.

@brianjarvis
Both doctors say the FDG scan is useless in prostate cancer at 1:50 into this video. I never changed that opinion in this video.

It can find neuroendocrine prostate cancer, however.