Bone scan vs PSMA PET scan

As far as I know, bone scan can detect many other things beside cancer - infection, fracture, arthritis etc. I also think that if it was something of importance that your doctor would already call you or sent message to inform you about it. However- I can totally see how unnerving that might be : (((, and on top of everything you have to wait till Monday. *ughhh Can you call them tomorrow and ask about that spot ?

From everything I read this is probably not serious. My MO prefers to talk about these things at our appointments and since I have one on Monday, I’ll just wait until then and try to put this out of my mind.

Dr. Johnson (of Mayo Clinic) talks about all this in his presentation, starting with the scans we’ve all heard about (MRI, bone, & CT scans), and then going into detail about PSMA PET: https://youtu.be/JoJomACA5UM

(He also discuss the value of MRI, bone, and CT scans in support of PSMA PET scans. This basic information might help as you meet with your MO on Monday.)

They can all produce false positives (PSMA-PET most of all, I think), so using more than one type of scan can help make them more confident about separating the signal from the noise. E.g. if something shows up on all three, then there's a stronger chance it's cancer-involved than if it shows up on just one.

Here's an example with two scans. I had a metastasis on my spine in 2021, which was treated with emergency debulking surgery and then radiation. My most recent CT scan last spring showed some lucency there, but a bone scan (which would be more accurate for the spine) showed nothing. Combine that with the facts that my ALP blood test is in normal range (it would often be elevated with a new bone metastasis), that my PSA remains undetectable (< 0.01) on the ultrasensitive test, and that it's exactly where the surgeon operated and fused my spine with cement and screws 4 years ago, and both the radiologist and oncologist are highly confident that the CT lucency is just showing my bone healing, not anything cancer-related. (Still, we plan an MRI next week just to be extra, extra certain.)

That's the way it goes. No one test is decisive, but the more positives you get, the more "votes" you have that there might be cancer.

Do PSMA pet scans commonly produce false negatives?

They all produce false negatives to the extent that there can be micrometastases too small for them to detect, but PSMA-PET is the most sensitive of the three (and also, I think, the "noisiest").

So no scan or blood test will tell us we're cancer-free — that medical technology doesn't exist yet. The best they can tell us is "nothing has grown big enough to show up on our radar yet." 😕

(But that said, I think results from the multi-faceted STAMPEDE trial suggested that if your metastatic prostate cancer remains castrate-sensitive for 5 years, you have a high chance of having entered long-term remission
🤞).

My MO ordered a CT scan, which I did yesterday. Waiting for results ….
From everything I read, a prostate cancer met by itself on the frontal bone is extraordinarily rare. Mets to the base of skull are also less common and usually appear for very advanced cancer.