PSMA PET SCAN AND PSA

[Tally111]

I had a disagreement with my RO today and wonder if he is right. My last PSMA PET Scan in Dec 2023 showed no progression. End January onwards I have an on off pain in the left ribcage area with an increasing frequency. To recap....PT3bN1Mx, RP in 2019, IMRT 2020 and on ADT for 30 months, currently completed a 20-month ADT vacation. Current PSA is <0.01. Since my PSA at detection in 2019 was only 4. 5 and the PET scan showed all mets, he is recommending a fresh PSMA PET Scan to rule out mets to bones as he feels in my case PSA is not an equivalent indicator of spread when compared with usual detections with a much higher PSA. Is there merit in his advice? Shall be grateful for any suggestions.

[GP24]

It seems that you have a bone met and it is possible that it has grown in size so it can be detected with a PSMA PET/CT. No guarantee though.

[Tall_Allen]

NaF18 PET scans are less PSA-dependent and are twice as sensitive to bone metastases.

[Tally111 in reply to Tall_Allen]

Is it correct to presume then that in cases with initial low PSA on detection, PSA levels may not necessarily be a good indicator of mets and a PSMA Scan with nondetectable PSA may still show mets?

[Tall_Allen in reply to Tally111]

No. Please re-read what I just wrote. NaF18 PET scans have twice the sensitivity for bone metastases compared to PSMA PET scans:

jnm.snmjournals.org/content...

PSMA expression is very dependent upon PSA.

[StayingOptimistic in reply to Tall_Allen]

TA,

. I did a psma scan on 1/2/2024 and it shows stable disease and no progression. My psa is < .01. I have been having back pain that is really bad. I work around the house so I am not sure if it is from the cancer? May be bone Mets which it never showed on the scan done in January or it is skeletal issue. strangely enough, last year I had the same symptoms and did an MRI which showed no cancer but degenerative disease in some back joints. Now, I am very concerned after reading your reply. Any thoughts please on what I should do? Thanks

[Tall_Allen in reply to StayingOptimistic]

Degenerative disease is obviously the culprit. It occurs as we age.

[GP24]

These researchers report that a PSMA PET/CT is more sensitive:

guoncologynow.com/post/dete...

[LearnAll]

There is NO clear correlation between PSA number and extent of disease....There are men here who started with PSA in range of 1000...to 5000..and has done fine for many years. The low PSA high extent of mets is more dangerous as the really bad cancer cells either does not release PSA or releases much less PSA.

In general, Ga68 PSMA PET CT is most sensitive scan. If you have high LDH or high Chromogranin A, a Dotatate scan can tell if you might have Neuro endocrine variant or mixed variant..

[Leader4077 in reply to LearnAll]

This is an interesting statement….”There are men here who started with PSA in range of 1000…..to 5000.. and has done fine for many years”. I have had a rapidly rising PSA that “exploded” from 40 to 250 in about 7-8 months. I was diagnosed and initially treated for PCa 20 years ago. Last 3-4 months have been fastest rising PSA ever…….only taking 120mg Orgovyx daily now despite history of 15 rounds of Docetaxel in the last 3 years that lowered PSA until the last 2…..any thoughts?

Mike B

[kiteND]

For some of us, PSA is never a reliable indicator. My PSA was less than 2 when I was diagnosed stage 4, and I had lots of mets. (almost all treated with chemo.) After starting ADT, my PSA has always been undetectable, but twice during the last 20 months, new mets have appeared. That is why I get a PSMA (Ga68) or a Choline 11 scan every three months.

During this journey, I have met up with, by internet and in person, other men in the same situation.

[StayingOptimistic]

we are both almost in the same situation. I did a psma scan on 1/2/2024 and it shows stable disease and no progression. My psa is < .01. I have been having back pain that is really bad. I work around the house so I am not sure if it is from the cancer? May be bone Mets which it never showed on the scan done in January or it is skeletal issue. strangely enough, last year I had the same symptoms and did an MRI which showed no cancer but degenerative disease in some back joints. Now, I am very concerned after reading your post.

[j-o-h-n]

Relying on a PSA score is akin to waiting for your bride as she walks down the aisle. Do I bite the bullet or look for the nearest exit?

Good Luck, Good Health and Good Humor.

j-o-h-n