Psma PET with/without contrast(dye) - Advanced Prostate...

Advanced Prostate Cancer

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Psma PET with/without contrast(dye)

Prostate72 profile image
37 Replies

My dad has been asked to get psma pet scan done.RP was done in jan 20. Current psa 0.20. (increased from 0.15 in 5 mnths)gleason 9& 10.detected nov.2019. positive margins.

As i am inquiring about the cost ,i came across all the hospitals asking me do you want to do the scan with contrast (dye)or just plain psma scan.last year when we did the first scan no1 asked me this,it was only one scan psma pet scan.

I am confused whats the difference between the 2. Which is better?

37 Replies
Cooolone profile image
Cooolone

Do you have access to a Major Cancer Center? One of Excellence...? Best results always occur with those most experienced to provide the procedure or care required. The PSMA-PET scan uses an agent which binds with secretions made primarily by PCa cells. I'm unfamiliar with what they may be referencing as to "contrast", especially if proposed to be "along" with the PSMA.

But as a suggestion, when these type of questions occur, it's important to identify exactly what they're talking about. It's ok to ask "what" contrast is proposed being used specifically, by name, and if they have any literature to review on it! This will eliminate any confusion in regard to "pOtato" or "potAto"... Lol

Best Regards

GP24 profile image
GP24

Some people are allergic against contrast, I guess this is the reason they ask. The results will be better with contrast.

However, I would wait at least until the PSA value reaches 0.5 ng/ml. The value of 0.2 ng/ml is too low and you may only detect about 10% of the existing lesions. So it may turn out to be a waste of money.

up.picr.de/37132434dl.png

Prostate72 profile image
Prostate72 in reply to GP24

Doc is planning for salvage radiation due to positive margins, and had a small spot on the rib but docs were not confirmed as uptake was too less,hence he has asked to get it done ..now m confused..

GP24 profile image
GP24 in reply to Prostate72

Get your prostate radiated and do not worry about the spot. Single spots are mostly false positives. See this study:

bjui-journals.onlinelibrary...

"Our results indicate that the vast majority of these lesions have low‐intensity uptake and are benign. Intervention to confirm this is not usually required. "

Justfor_ profile image
Justfor_ in reply to GP24

From the link you just posted:

"A lesion was considered benign if the prostate‐specific antigen (PSA) level remained <0.1 µg/L following a radical prostatectomy (RP)"

Please be advised that he has at least two PSAs greater than 0.1.

GP24 profile image
GP24 in reply to Justfor_

I think 0.2 is still very low. Trying to treat this spot is overtreatment. Just get another PSMA PET/CT in a year from now if the PSA value continues to rise.

Justfor_ profile image
Justfor_ in reply to GP24

In the meantime should he get sRT and if yes, to what extent?

GP24 profile image
GP24 in reply to Justfor_

Prostate72 wrote: "Doc is planning for salvage radiation due to positive margins". So I thought this is already decided. Many doctors start with sRT when the PSA level gets over 0.2 ng/ml.

The extent I mentioned below, it depends on the result of the PSMA PET/CT.

Justfor_ profile image
Justfor_ in reply to GP24

Let me elaborate in the content of the graph you just posted.

In the lowest PSA range <0.5, 38% of scans led to a positive detection.

The remaining 62%, if any spots existed, they were smaller in size than the lowest detectable size.

These 38% cases are broken down to :

Prostate bed: 6%

Pelvic Nodes (N1): 16%

The remaining 16% represent spots in multiple regions or extra-pelvic.

Consequently:

If in this sample of patients sRT to prostate bed only were administered in would had a 6/38=16% success rate.

If the pelvic Nodes were also included, the success rate would had risen to (6+16)/38=58%

Do you have any insight regarding the rest of not detected 62% as having a vastly different break down? I don't and when in doubt, I would put my money on the homogeneity of the total population against any unsubstantiated argument of the sort: "If we can't see it it must be confined in the prostate bed/pelvis".

The statistics of blind sRT giving a success rate from 40% to 60% just do me justice.

GP24 profile image
GP24 in reply to Justfor_

The intention of the PSMA PET/CT was to decide if you should include the pelvis in the salvage radiation. Otherwise there would be no reason for that. If no mets are detected in the pelvis you should skip radiating the pelvis and avoid its toxicities. If mets show up in the pelvis in the coming years, you can radiate these with SBRT or get a separate IMRT radiation to that area.

Prostate72 profile image
Prostate72 in reply to GP24

Coool...so if no mets will avoid radiation..

GP24 profile image
GP24 in reply to Prostate72

The positive margins provide a reason to radiate the prostate, so this should be done. But if the PSMA PET/CT does not detect any mets you can avoid extending the radiated area to the pelvis which often causes side effects.

Justfor_ profile image
Justfor_ in reply to GP24

When you write "radiate the prostate" do you mean the prostate bed, because his father has no prostate anymore. He had RP in Jan. 2020.

GP24 profile image
GP24 in reply to Justfor_

Yes, forgot the bed. I meant prostate bed.

Justfor_ profile image
Justfor_ in reply to GP24

Thanks for clarifying.

maley2711 profile image
maley2711 in reply to GP24

Is that graph based on Ga PSMA PET? or some other tracer?

GP24 profile image
GP24 in reply to maley2711

Yes, its from a study using the Ga68 PSMA PET/CTs at UCLA/UCSF:

ncbi.nlm.nih.gov/pmc/articl...

Justfor_ profile image
Justfor_ in reply to maley2711

There is also this paper from AmsterdamUMC :

journals.plos.org/plosone/a...

It shows a similar break-down, though a substantially higher positive detection rate (58% for PSA<0.5). They used 18F-DCFPyL radioligand which seems to be a bit more sensitive.

Justfor_ profile image
Justfor_

This subject comes up all the time. I have posted about it an uncountable number of times. In essence it is a compromise decision. It needs to be early enough for better sRT outcome, vs later for a better PSMA PET/CT detection probability. The PSMA PET/ CT doesn't depend only on PSA. PSADT (doubling time) is equally or even more important. Your father has a high PSADT judging from the sheer fact that he reached 0.2 (PSA velocity) one year after RP. Also, things that doctors do not understand (information theory is not taught in medical schools): An absence of detection is not information void. It is the complement of a successfully detected one. This, in practice, translates to: "If anything at all, it is smaller compared to the minimum detectable size". There is a recent paper from Italy that claims a negative PSMA scan to lead to a better sRT success rate.

Tall_Allen profile image
Tall_Allen

Your PSA is too low to detect anything. You can increase detection by starting ADT, but you may not need ADT. The contrast is for the CT scan - if you're not allergic to iodine, go ahead with it.

Prostate72 profile image
Prostate72 in reply to Tall_Allen

Sorry forgot to mention he is on pamorelin 22.5 injection every 3 mnths..we are located in mumbai india..have seen docs prefer pamorelin over lupron here

Tall_Allen profile image
Tall_Allen in reply to Prostate72

Then the ADT trick won't work. And it isn't likely a scan will be useful.

tango65 profile image
tango65

The results are better for localization of lesions when iodine contrast is used for the CT scan. If you are not allergic to iodine and your renal function is OK, the contrast could be used.

Whole pelvis radiation associated with short term hormone therapy seems to be to most effective treatment to control the cancer.

astro.org/ASTRO/media/ASTRO...

Detection rate for Ga 68 PSMA PET/CT is around 30 to 40% at a PSA 0.2 and it could be related to the PSADT.

ncbi.nlm.nih.gov/pmc/articl...

ncbi.nlm.nih.gov/pmc/articl...

Justfor_ profile image
Justfor_ in reply to tango65

From the first paper:

"At PSA of <1 ng/ml/y the PR of PSAvel was 50% and increased to 98% at PSA >5 ng/ml/y. No significant association was found for PSAdt."

Medical maths, my foot.

PSADT is the integral over time of PSAvel, or seeing it the other way round, PSAvel is the time derivative of PSADT.

There is NO way of any sort of assossiation with one and not the other.

The word that saves face for the authours is "found".

Undoubtly there is, but they just couldn't "find" it. Why?

Because, as anyone who has followed a course in measurements knows, the integral has one order of magnitude LESS variance over the underline function.

tango65 profile image
tango65 in reply to Justfor_

I wonder if it is related to how the patients arrived to the PSA level they had when they were studied. You could have many patients with many different PSADTs which were studied at the same PSA interval. Patients are selected to this type of study based on their PSA regardless of their PSADT.

Justfor_ profile image
Justfor_ in reply to tango65

PSADT and PSA velocity are two different metrics of the exact samething. The time sequence of the person's PSA. I have in my computer some 20 papers on the subject. The second link that you posted, the one from Heidelberg, is my favourite. I had missed the first one, so started reading it. Passing over the offending paragraph, I just stopped. If they are that clumsy to write such things, then they are not serious enough to spend time for reading any further, I thought and didn't go any further.

BAZZAD1953 profile image
BAZZAD1953

Has your farther had his prostate out? With PSA readings of 0.15 & 0.20 these indicate he’s had treatment done. But then you mention his Gleason scores which indicate he still has his prostate? Which is correct?

Prostate72 profile image
Prostate72 in reply to BAZZAD1953

Yes rp in jan 2020, dec 19 took pamorelin 22.5 injections which he takes every 3 mnths psa was stable at 0.15 till August November 0.19 ,jan 21 .. psa 0.20

maley2711 profile image
maley2711

Here is a read on tracers and contrast...

mskcc.org/cancer-care/patie...

Contrast helps the Doc have a better look.....but some folks have allergic reaction?

Were it me, I'd ask for an explanation from the institution!!!

MateoBeach profile image
MateoBeach

Sorry there are many conflicting opinions here but I must add what I know. PSA level of detection for either PSMA scan isotope (Ga68 or DCFPyL) is 0.20. That is the cutoff for UCLA in their protocols. It is not futile. My PSA was 0.23 when I found 2 cancerous lymph nodes in my pelvis by this scan that were subsequently irradiation.

No other “contrast is used in PSMA PET scans other than the isotope and binding ligand that causes it to bind to the PSMA molecule on the surface of cancer cells 68-Ga-PSMA-I&T and other variants).

MateoBeach profile image
MateoBeach

3. The question about contrast was just a routine one for those doing intakes and are not applicable. So just answer no if you are not allergic to iodine, etc. 4. The standard radiation field now recommended for salvage radiation therapy includes the pelvic lymph nodes as well as the prostate bed ( extended field per RTOG guidelines).

So my personal suggestions is: go for the PSMA scan now to see what it can show. If there are PSMA avid lesions outside of the pelvis already then you are already metastatic and the salvage RT would be futile. If there are no such lesions outside the pelvis then I would certainly go for salvage RT including the PLN fields. One year or up to two years of ADT of adjuvant (accompanying) has been shown to improve chances of long term success. So this should be used. These are my own opinions from research of this and my own experience. Good luck to you sir.

j-o-h-n profile image
j-o-h-n

How old is your Father? (72?)

Good Luck, Good Health, and Good Humor.

j-o-h-n Friday 01/22/2021 5:08 PM EST

Prostate72 profile image
Prostate72 in reply to j-o-h-n

73 now..but quite fit..

j-o-h-n profile image
j-o-h-n in reply to Prostate72

That's great....... tell him to keep eating "roti and dhal" to keep him fit. Regards...

Good Luck, Good Health, and Good Humor.

j-o-h-n Friday 01/22/2021 7:23 PM EST

Prostate72 profile image
Prostate72 in reply to j-o-h-n

Haha..ya roti dal &sabhji (vegetable)..he has turned vegetarian after detection

j-o-h-n profile image
j-o-h-n in reply to Prostate72

Good.... less meat for him...... more meat for me.........

I say this to most East Indians that speak Hindi..... See if you get it.....

When I am leaving them instead of saying "namaste"

I say "youmuststay" and I must go.....

Good Luck, Good Health, and Good Humor.

j-o-h-n Friday 01/22/2021 7:37 PM EST

Cooolone profile image
Cooolone

The G68-PSMA-PET is superior to the F18 agent... I suggest those who are interested to find and actually read the data on the studies performed. They used more agent and allowed it to dwell longer for additional uptake on the F18 scans. F18 has been pushed because it's more durable and can travel, allowing remote facilities to offer it. I don't recall the particulars, but that's what I remember between the two. Other relavent data has already been posted as to it's efficacy and sensitivity (G68).

Best Regards

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