PSMA PET with undetectable PSA, how to confirm right imaging order?

Posted by pcasurvivor @pcasurvivor, Jan 9 7:59pm

Hi! New to the forum and a fellow cancer survivor (so far!). I had an Xray taken recently (for kidney stone monitoring--the least of my medical concerns, but nonetheless...) and they detected growth in a bone lesion (thought previously to be a benign bone island). Since I now have a history of cancer (PCa diagnosis a year ago, followed by RP) they ordered a PSMA PET scan. I'm not sure this is the right next step since my PSA level has been undetectable since surgery (every 3 months), so I didn't think PSMA PET would detect anything. Urology is deferring to Radiology on choice of imaging. Can't seem to talk to radiology to make sure a PSMA PET scan is right in this case--they just have an appointment phone number and refer you back to the ordering Dr if you have questions... but he deferred to them... and so the circle is complete!). (This is not at Mayo.) Has anyone had a similar situation? If so, what did you do? Thanks!

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hbp | @hbp | Jan 9 8:18pm

A pet scan does not hurt and it can discover the spread of PC that PSA might miss. Cancer is a serious matter and you have to take the medical steps that minimize your risk and prolong your life and the quality of your life. Best of luck!

jc76 | @jc76 | Jan 10 5:58am

@pcasurvivor
Can pass on what I was told and recommended to me. Mayo Clinic did a bone scan upon my diagnosis of prostrate cancer. It came back negative. It looks directly at the bones.

My oncologist/radiologist ordered a PETSCAN (PSMA) to look at tissues, organs etc. to further check if cancer had spread.

I think both would be a good recommendation but as always should talk to your oncologist/radiologist and discuss you concerns with them and the reserach you are doing. What you will see here on MCC is we all say question, reserach, get second opinions. Then decide.
Good luck!!

web265 | @web265 | Jan 10 6:47am

The issue with the PSMA PET scan is if it finds something, great, now you know it's there. It can miss cancer. When my PSA started to go up after RP a scan was ordered for me. It was negative yet the PSA kept rising, next step was salvage radiation even though the scan was negative.

If attempting to find cancer because PSA is rising, the chance of finding cancer is related to the PSA at the time. See the chart...

Having said that, if the scan is being directed and has a particular focal point, perhaps it's more accurate, that's just a possibility not something I know to be true. If it's covered by your insurance, there's probably no harm in it.

wellness100 | @wellness100 | Jan 10 12:08pm

Did you have a MRI or bone scan or only X Ray?

pcasurvivor | @pcasurvivor | Jan 10 3:14pm

Thank you, everyone, for your help. The bone lesion was noted 8 years ago from a CT and classified as a bone island. In Xrays over the years, it has consistently grown. In a recent Xray, it had grown more quickly than before thus the warning flag raised by radiology.

(A complication I created was by going to a different institution for PCa care (high volume, got in quicker, they have more clinical trials, etc.), ... so kidney at one, PCa at another, and the 2 don't share EPIC/MyChart data, so limited visibility for the Drs involved.)

As a follow up to my original post, I was able to get time with my PCa urology oncologist (at the other institution) and he said that PSA is more sensitive then PSMA in detecting recurrence, and a PSMA PET scan would be unlikely to show anything since my PSA is undetectable. (He is involved in PSMA theragnostic research, clinical trials, and has published papers on the topic.) This aligns with @web265 's comments and chart: low PSA --> low chance of finding cancer with PSMA PET.

I was also able to get a referral to orthopedics oncology, so will get their advice on next steps before proceeding with further imaging.

Here's a (maybe unfounded) worry... my PCa is aggressive (IDC with cribriform pattern) and so the chance of BCR is very high. I don't want to get a PSMA PET scan now and get nothing, and then when BCR raises it's ugly head in, say 6 months and want a PSMA PET scan, the insurance says you just had a scan.

Cancer is a hard row to hoe... Thanks again for all your help!