pSMA scan question

[Chris52981]

If you get a pSMA scan and you have prostate cancer that metastasized does it alway express PSMA?

What cases will it not?

Also when psa goes up does that necessarily mean there are new metastasis or can it just means same ones are active again?

[Poowater]

No, to the first question. Getting an FDG scan either shows other metastases, or not. When psa goes up either could be expressing psa.

[Tall_Allen]

It expresses PSMA about 90% of the time, but as it progresses, it may not express PSMA. Also metastases are heterogeneous- some cells express PSMA and some do not even within the same tumor. Also, within the same patient, some metastases may express PSMA and some may not.

"Also when psa goes up does that necessarily mean there are new metastasis or can it just means same ones are active again?" Either.

[Chris52981 in reply to Tall_Allen]

so what exactly is the point of the PSMA scan to see what treatments your body may respond too? I'm just a bit confused still on the whole reasoning! Thanks for explaining

[Tall_Allen in reply to Chris52981]

That's why I advocate getting both a PSMA and an FDG PET scan.

[fmenninger in reply to Tall_Allen]

also, sometimes it’s easier for Mo to call for an fdg pet vs psma pet and having both can provide more info.

[dhccpa in reply to Tall_Allen]

Great feedback from you on this topic. Is the FDG PET known by another name? I had a PET Bone Scan the first time four years ago, but the report details call it something else besides FDG.

[Tall_Allen in reply to dhccpa]

Sometimes called a glucose PET scan - FDG=FluoDeoxyGlucose. As cancer mutates, it loses PSMA expression and metabolizes glucose, like most other cancers do. Bone PET scans are Sodium Fluoride (NaF18).

[dhccpa in reply to Tall_Allen]

Thanks. Yes, I believe it was NaF18 that I had back then, so I've never had the FDG scan.

[Chris52981]

do you want it to express PSMA or no?

[Tall_Allen in reply to Chris52981]

PSMA targeted therapies (e.g., Pluvicto or some BiTEs) require PSMA avidity in order to be effective.

[Chris52981 in reply to Tall_Allen]

is a psa of 1.2 very high you think to show PSMA or Mets

[Tall_Allen in reply to Chris52981]

It should show any PSMA-avid tumors.

[lewicki in reply to Tall_Allen]

Would a PSA of 0.04 PSMA pet show cancer and would an Auximin pet scan be a good choice ?

[Tall_Allen in reply to lewicki]

No- neither is a good choice at such low PSA

[lewicki in reply to Tall_Allen]

Thanks. If you suspect cancer may have mutated would the FDG scan be an option. At what PSA will the PSMA scan work?

[Tall_Allen in reply to lewicki]

No scans before PSA=0.5

[lewicki in reply to Tall_Allen]

Again thanks.

[garyjp9 in reply to Tall_Allen]

If your MO is suggesting you stop ADT +ABI at the 2+ year mark because your PSA is undetectable (following an RP, N1 disease, and initial post-surgery PSA of 3.4), is there any value in getting an FDG scan or any other kind of scan (not PSMA) before doing so? Thank you.

[Tall_Allen in reply to garyjp9]

Probably not. Unlikely that you have non-PSMA-avid metastases.

[garyjp9 in reply to Tall_Allen]

Thanks, I thought maybe I should ask for a scan before stopping treatment after reading this report on an analysis of ARCHES data by Andrew Armstrong: dailynews.ascopubs.org/do/a... Is this not relevant to the situation I've described here?

[Tall_Allen in reply to garyjp9]

That trial was for men who were metastatic- you're not. I think you had potentially curative adjuvant hormone therapy, no?

[garyjp9 in reply to Tall_Allen]

Thank you for responding, TA. My metastases were confined to the pelvic lymph nodes, but I am often confused about how to categorize them in the context of studies like this, as to whether they qualify as "metastases" or not. Yes, I have had surgery, radiation (#39), and ADT+ABI (2+years) since 9/20.

[Tall_Allen in reply to garyjp9]

It's confusing because pelvic lymph nodes (stage N1) technically are metastases, but in trials like ARCHES, STAMPEDE, etc., they use the term "metastatic" only to refer to more distant metastases (stage M1).

[garyjp9 in reply to Tall_Allen]

Thanks very much for explaining, TA

[lewicki in reply to Tall_Allen]

Is their any harm doing the scan often or just occasional?

[Tall_Allen in reply to lewicki]

Yes- it's radiation from both the radioindicator and CT- do it only when needed.

[Justfor_ in reply to lewicki]

A nomogram predicts a 18% probability for a PSMA positive detection at PSA less than 0.1 and a PSADT of 3 years or more, if memory serves. For PSADT shorter than 3 months it can double up.

[Chris52981 in reply to Tall_Allen]

so if there are no pSMA avid tumors will it just show plain Mets too? Also if it doesn't show pSMA avid tumors does that mean it could be nueroendocrine or not necessarily? Thanks again

[Tall_Allen in reply to Chris52981]

No PSMA-avid tumors show up at such low PSA. PSMA PET only shows tumors with PSMA expression. Conventional imaging can sometimes show larger tumors that do not express PSMA. Many tumors do not express PSMA.

[Chris52981 in reply to Tall_Allen]

6 months ago he received a CT scan of chest and abdomen and he was on Zytiga - it showed little change in measurable disease- they switched him to xtandi bc his Psa was rising and then he went into adrenaline insufficiency and had to stop xtandi and titrate back up- his psa went down went he went on xtandi then a month later they took him off because of symptoms which turned out from not being on prednisone- now he is back on the four pills since January and his psa went up like I said from .6 to 1.2 in three months ( got in beginning of march) - now he wants to give him the pSMA scan on Wednesday- so i am not sure this is the correct way to go about it? Obviously we listen to dr but I also want to make sure there is not other test we should be asking for as well. He had Axumin in past as well- do you think that sounds like a good plan-?

[TeleGuy in reply to Tall_Allen]

Never say "never." Here's a left paraaortic lymph node at SUV=6.1 on a PSMA PET scan while my PSA had been <0.01 for 11 months post Lu177-PSMA treatment. We wanted to see where there might be residual disease after treatment and we found several locations.

PSMA PET scan image

[Tall_Allen in reply to TeleGuy]

How do you know it's a true positive? Was there a CT correlate? SUV max=6.1 probably isn't far enough above background to make a definitive call.

[TeleGuy in reply to Tall_Allen]

We did a biopsy of one on the other side of the aorta that wasn't as avid. Adenocarcinoma with neuroendocrine differentiation. Then we radiated the collection of them.

[Tall_Allen in reply to TeleGuy]

You may want to explore some clinical trials:

prostatecancer.news/2016/12...

[TeleGuy in reply to Tall_Allen]

Thanks. We're considering the BiTE trials but plan to do a biopsy of what's changed since I did 6 cycles of docetaxel+carboplatin.

[Hidden in reply to Chris52981]

there are therapies that assume/require psma.expression .Those therapies then have a chance of being effective.

[tango65]

Cancer mets which do not express PSMA may be bad news, since neuroendocrine PC expresses little PSA and PSMA and it is practically impossible to control.

The regular adenocarcinoma expresses PSMA and PSA and it is usually easier to control than cancer which does not express PSMA or PSA.

The Vision trial leading to the approval of Lu 177 PSMA treatment did not accept patients with mets having a PSMA expression lower than the liver .

Since the mets are not homogenous with all the cells expressing PSMA, it is necessary to have in the mets enough cells expressing PSMA which can attach to the Lu 177 and irradiate themselves and the non PSMA cells in their proximity. Beta particles can travel a few mm in the tissues.

[Chris52981]

thank you everyone! Makes so much more sense!

[fmenninger in reply to Chris52981]

This is why we should not rely 100% on just psa. As many in this forum have said, we warriors are not fighting psa but rather pca and psa is one of many bio markers and new tools such as psma pet scan should be used when warranted.

Stay strong!

[wagscure259]

In my case doubling times of PSA were 3-6 weeks and scans showed rapid lymph node disease progression. After 10 years of treatment with Lupron, bicalutamide and darolutamide when progression was noted I had both a PSMA scan, FDG scan, bone scan, and biopsy of positive lymph node to rule out neuroendocrine PCA ( along with histochemical testing- because at the time of rapid progression my PSA was around 2), still adenocarcinoma and my cancer was NOT PSMA avid but FDG scan reveal extensive retroperitoneal and pelvic side wall lymph node metastasis. Presently being treated with docetaxel with favorable responses after 3 rounds. Best to you.

[Gl448 in reply to wagscure259]

How did they determine favorable responses after three rounds? PSA levels or something else

I have my 4th round in 2 days and PSA has dropped, but I’m one of those whose cancer doesn’t express (much) PSA.

[wagscure259 in reply to Gl448]

Primarily from CT scans of chest, abdomen and pelvis demonstrating considerable lymph nodes shrinkage. Bone scan remains clean (extensive metastatic disease in bones at diagnosis in 2013). PSA was 12.88 just prior to first round of docetaxel and after third infusion it reduced to.78. No other explanation for this reduction other than the chemo. Best to you

[Gl448 in reply to wagscure259]

That’s great news. I wasn’t sure if you’d had scans after only three sessions.

[Hidden]

Non PSMA avid pCA is DNPC or NEPC, negative for FOLH1 and AR. The pCA cells rely on GLUT1, they will be FDG avid. They will probably show DLL-3, lu177-DPRA-SC16 maybe a possibility in 2023.

pubmed.ncbi.nlm.nih.gov/318...

[Largebill]

The answer to any questions regarding prostate cancer that have absolutes (always or never) will be no. This disease behaves differently in each of us and responds differently to the various types of treatment for each of us. Having said that, the PSMA test should identify any active areas in your body. I just had a PSMA last month. They inject you with some radioactive stuff that is supposed to seek out any PC in our body. They wait about 45 minutes for the stuff to circulate in your body and then do the scan. Mine showed activity in my shoulder (scapula). As to PSA rise, that can be an indicator that something is going on, but PSA alone doesn't tell your doctor much. It can be an old metastatis or a completely new development. Best of luck going forward.

[Benkaymel in reply to Largebill]

"the PSMA test should identify any active areas in your body"

- this is what confuses me. I had a PSMA scan in January that showed PSMA avid tumours and my MO said that meant they were "active", BUT they are not growing. I thought active meant growing whereas PSMA avid just showed they were "regular" adenocarcinoma. Can someone clarify?

[Chris52981]

when you orginally get a biopsy it states which one correct? Could they change - are the other ones that are not adenocarcinoma harder to treat?

[awb1]

In my case, psma showed a single node in my neck when my PSA was .08. It was removed surgically. In another case of mine, psma showed 4 small lung nodules when my PSA was .06 and they were ablated with cryo by an interventional radiologist.. In another case of mine fdg showed a single node in my neck when PSA was .02 and it was removed surgically. I suppose if you have 10 micromets and a PSA of .05 you wouldn't see them with a psma, if there's a single node then you might see that one. A matter of concentration to some point of scan threshold. The fdg reveals small issues, it's nice to have history and the same radiologist reading to compare and looking for changes; progression and remission. I get one or the other scan every 3-4 months. I toss in a short series of taxotere every few years as a rinse. I'm on my own custom BAT and keeping my PSA < .006. I'm kind of weird in what I'm doing and work with an open-minded MO and a closed-minded MO, navigating between the rails, transparent with all. They trust me and learn as well.. I don't do clinical trials because I can't pivot and do my own thing. I'm probably disqualified from eating toast I've had so much stuff for 20 years. That's all I have to offer on this thread, thanks. Have a nice week.

[Chris52981 in reply to awb1]

wow makes me have hope! Are you Castrate resistant I assume

[lewicki in reply to awb1]

can I talk to you one on one?

[awb1]

I once was. ADT would kill me. Look up BAT. That's all from me on this thread, thanks.

[Chris52981]

yes my dads pathology was adenocarcinoma - just wondering if that can change later on meaning the cancer