Apparently, seeing a 5mm uptake on the PSMA scan doesn't mean there is a 5mm tumour there. Research in 2022 suggested that about 10% of positive PSMA scans (and as much as 30% in men with BPH) are false positives - e.g. there are other reasons for PSMA uptake, particularly in lymph nodes and salivary glands. The executive summary says:
"As PSMA PET scan use has become more common, we are also encountering an increase in false positive findings. Other malignancies can be detected via PSMA PET, as well as infections and benign processes such as Paget’s disease. We therefore recommend careful evaluation and verification, including potential biopsy, to confirm the diagnosis."
It also suggests that where there are only limited uptake sites or the uptake is in places that PCa would not usually metastasise, an MRI should be done to confirm whether the PSMA is correct.
Did you ask the registrar to clarify why he was saying the lymph node was clear when the oncologist had led you to believe it wasn't? What was his response? Can you email the consultant's secretary and ask for clarification?
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Extract:
TABLE 2: Diagnostic Performance of 68Ga-PSMA PET/CT in Initial Detection of Prostate Cancer With
Histopathology Results as the Reference Standard
Author [Ref] No of Patients TP FP FN TN Sensitivity (%) Specificity (%) Accuracy (%)
Hoffmann [17] 25 21 0 2 2 91.3 100 92
Lopci [18] 45 11 14 0 20 100 58.8 68.9
Sasikumar [19] 66 50 6 0 10 100 62.5 90.9
Kumar [20] 15 8 2 1 4 88.8 66.6 80
Zhang [21] 58 33 4 3 18 91.6 81.8 87.9
Liu [22] 31 14 4 1 12 93.3 75 83.9
Lopci [23] 97 23 41 0 33 100 44.6 57.7
Note—PSMA = prostate-specific membrane antigen, TP = true-positive, FP = false-positive, FN = false-negative, TN = true-negative.
Edited by member 17 Jan 2024 at 00:26
| Reason: table layout problems
"Life can only be understood backwards; but it must be lived forwards." Soren Kierkegaard
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Brian, I did ask Jamie about PSMA and MRI detection. Unfortunately there wasn't a definitive answer,he agreed that even in our situation there are false positives and negatives with PSMA scans. He went on to say that a PSMA scan may show something that MRI didn't and vice versa.
He didn't offer an explanation why a positive PSMA hot spot would then be deemed not to be cancer.
Hopefully you will soon get an explanation and treatment plan. The encouraging thing was that once a lymph node was treated there should not be a recurrence in that lymph node.
Thanks Chris
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Note that most PET scans are currently PET-CT scans, which is a PET scan image (which shows just hot spots) overlaid on a CT scan image, so they can see which organs are hot. This article is talking about PET-MRI scans which are PET scan images overlaid on MRI scans.
There are some PET-MRI scanners at the top treatment centres and private hospitals in the UK, but most PET scanners are PET-CT scanners.
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Hello Briannisac,
I am not a scan expert but my urologist and surgeon told me the PET PSMA is the most accurate tool.
My surgeon asked me to do it before the surgery to have a correct stadiation, despite I had already done a MRI and a biopsy.
Obviously other experts can share their view, this is my experience
Good luck!
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Thanks Fed, that’s what I thought and why I’m a bit confused
Bri
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Yes, I would be confused by that too. A PSMA PET scan should give better results for a lymph node than an MRI scan.
Jules
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Brian, I didn't have any MRI scans after my PSMA scans, in fact I have only had one MRI scan in connection with my cancer and that was ten years ago after my biopsy. My PSMA scan did pick show uptake in areas that were not considered to be cancer.
The image of my first PSMA scan just shows a single spot, high lighted by a different colour on the image.
Thanks Chris
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Thanks all
Chris that was my impression ie that the PCa would specifically show up on the scan due to the contrast they had injected. The Oncologist certainly said there was a 5mm uptake.
I am thinking about requesting the radiologiy report. Not sure what else to do
Bri
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If you can obtain copies of the two scans you could have them reviewed by a top hospital. Sometimes you can get this done by one hospital doing what they did in my case with another, which they referred to as 'calling over'. In my case there was doubt about the Choline Pet scan being interpreted by my treating hospital as showing an iliac lymph node affected by cancer. Other hospitals disagreed so I paid for a 68 Gallium PSMA scan which did not show the questionable node as being affected. This meant I was able to have HIFU which would have been denied if the PSMA scan showed uptake. So glad I got other opinions.
Barry |
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Apparently, seeing a 5mm uptake on the PSMA scan doesn't mean there is a 5mm tumour there. Research in 2022 suggested that about 10% of positive PSMA scans (and as much as 30% in men with BPH) are false positives - e.g. there are other reasons for PSMA uptake, particularly in lymph nodes and salivary glands. The executive summary says:
"As PSMA PET scan use has become more common, we are also encountering an increase in false positive findings. Other malignancies can be detected via PSMA PET, as well as infections and benign processes such as Paget’s disease. We therefore recommend careful evaluation and verification, including potential biopsy, to confirm the diagnosis."
It also suggests that where there are only limited uptake sites or the uptake is in places that PCa would not usually metastasise, an MRI should be done to confirm whether the PSMA is correct.
Did you ask the registrar to clarify why he was saying the lymph node was clear when the oncologist had led you to believe it wasn't? What was his response? Can you email the consultant's secretary and ask for clarification?
*************************************************************************************************************
Extract:
TABLE 2: Diagnostic Performance of 68Ga-PSMA PET/CT in Initial Detection of Prostate Cancer With
Histopathology Results as the Reference Standard
Author [Ref] No of Patients TP FP FN TN Sensitivity (%) Specificity (%) Accuracy (%)
Hoffmann [17] 25 21 0 2 2 91.3 100 92
Lopci [18] 45 11 14 0 20 100 58.8 68.9
Sasikumar [19] 66 50 6 0 10 100 62.5 90.9
Kumar [20] 15 8 2 1 4 88.8 66.6 80
Zhang [21] 58 33 4 3 18 91.6 81.8 87.9
Liu [22] 31 14 4 1 12 93.3 75 83.9
Lopci [23] 97 23 41 0 33 100 44.6 57.7
Note—PSMA = prostate-specific membrane antigen, TP = true-positive, FP = false-positive, FN = false-negative, TN = true-negative.
Edited by member 17 Jan 2024 at 00:26
| Reason: table layout problems
"Life can only be understood backwards; but it must be lived forwards." Soren Kierkegaard
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I think Lyn hit it on the head.
Magnetic resonance imaging (MRI) scans use magnets and radio waves. PET scans use a radioactive tracer to show how an organ is functioning in real time. Both produce still images of organs and body structures. PET scan images can detect cellular changes in organs and tissues earlier than CT and MRI scans.
The point is 'cellular changes' which may or may not be cancerous.
I am sure a lot of it also comes down to the skill of the technician in interpreting because if you are lucky enough to be able to see your scans, then you can understand just how hard it must be to see anything at all :)
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Lyn, I noted that the table refers to initial detection of prostate cancer, I wondered if it also applies to the situation Brian and myself are in, i.e.scanning after RP and SRT.
I find out next week how effective my treatment has been based on a gallium PSMA scan.
Thanks Chris
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Thanks all,
I am still left a bit in limbo. I e-mailed the oncologist secretary. I explained I had been informed that there were now no signs of PCa when previously I had been told there was uptake in the lymph node.
Today the oncologist has replied to let me know “…the images are being discussed at MDT to further clarify”.
So why tell me there is definitely no cancer if further clarification is needed.
Not a happy bunny today
Bri
User
Does this scenario not also leave you pondering if there has been over treatment jn similar cases eg if I had not had the MRI scan to check out the unspecified uptake then they may have proceeded with SABR to the lymph node that may not be cancerous 😩
Bri
Edited by member 17 Jan 2024 at 16:05
| Reason: Not specified
User
As I said earlier - a lot is down to the skill of the technician. It does sound as though they are reviewing it all in the MDT which is good.
Could there have been examples of over treatment? Absolutely. But that is slightly better than missing something. Everyone is human at the end of the day and mistakes can, are and will be made.
But it sounds as though you are getting the peer reviews that you need.
User
Brian, certainly confusing and understandably annoying. My PSA had been rising before my SABR treatment, it was 1.8 just before SABR and just under eight weeks later it remained the same before then starting to rise again. Not sure if eight weeks was long enough to see a reduction. I was also surprised that nine months later a second tumor was picked up that was not previously seen. What tracer did you have , my first tracer was the 1004 and the second was Ga68.
I think it goes back to the title of your conversation, which scan is the most accurate .I will ask the question next week,but Jamie doesn't like answering my questions.
Thanks Chris
User
Interesting figures Lyn and I can well see why you had "table layout problems"
Of the 337 patients 56 out of the 71 false positives were credited to Lopci, so if you take out the Lopci figures there were only 15 out of 337 false positives.
I have no idea what this tells us but certainly Lopci [who claims to have greater sensitivity than anyone else at 100%] has a different approach to the other authors.
Jules
Edited by member 17 Jan 2024 at 23:06
| Reason: Not specified
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Originally Posted by: Online Community MemberDoes this scenario not also leave you pondering if there has been over treatment jn similar cases eg if I had not had the MRI scan to check out the unspecified uptake then they may have proceeded with SABR to the lymph node that may not be cancerous 😩
Bri
That was the premise of the research paper I quote above - that as PSMA becomes more popular and more widely available, there are increasing numbers of cases of overtreatment or undertreatment. The authors' point was that if PSMA is only highlighting one or two hotspots or hotspots in unusual places, an MRI should be done to confirm the PSMA findings. On that basis, your hospital was spot-on and maybe even ahead of the curve!
Some of you will remember that, when the medical sector started making noises about PSMA potentially removing the need for biopsy, I posted on here many times about how foolhardy that might be. John's onco told us that the only way to be really confident is to do all the tests - mpMRI, PSMA Gallium, PSMA Axumin and bone scan - as each has its strengths and limitations
"Life can only be understood backwards; but it must be lived forwards." Soren Kierkegaard
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Originally Posted by: Online Community MemberInteresting figures Lyn and I can well see why you had "table layout problems"
Of the 337 patients 56 out of the 71 false positives were credited to Lopci, so if you take out the Lopci figures there were only 15 out of 337 false positives.
I have no idea what this tells us but certainly Lopci [who claims to have greater sensitivity than anyone else at 100%] has a different approach to the other authors.
Jules
If we remove the Lopci data, that is 16 false positives out of 195 so yes, far lower than Lopci et al found. The main difference seems to be that Lopci's data all came from one hospital / scanner centre whereas the other researchers had cases from different hospitals. Also, Lopci's first set in 2018 was specifically about men who couldn't have MRI for some reason or their MRI had been clear so perhaps all the other data sources were covering men who had had MRI as well as PSMA?
"Life can only be understood backwards; but it must be lived forwards." Soren Kierkegaard
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Quote:That was the premise of the research paper I quote above - that as PSMA becomes more popular and more widely available, there are increasing numbers of cases of overtreatment or undertreatment. The authors' point was that if PSMA is only highlighting one or two hotspots or hotspots in unusual places, an MRI should be done to confirm the PSMA findings. On that basis, your hospital was spot-on and maybe even ahead of the curve!
You may be right Lyn. But maybe they should have told me they were discussing for further clarity at the MDT meeting rather than the registrar telling me it is definitely not cancer in the lymph node
Thanks for sharing the research. That has offered some good clarification
Bri
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Brian, I did ask Jamie about PSMA and MRI detection. Unfortunately there wasn't a definitive answer,he agreed that even in our situation there are false positives and negatives with PSMA scans. He went on to say that a PSMA scan may show something that MRI didn't and vice versa.
He didn't offer an explanation why a positive PSMA hot spot would then be deemed not to be cancer.
Hopefully you will soon get an explanation and treatment plan. The encouraging thing was that once a lymph node was treated there should not be a recurrence in that lymph node.
Thanks Chris
User
Quick update. Saw the Oncologist in February. She said they are now proposing a planning scan for SABR treatment which I have on Tuesday. She said this scan will determine if they can offer the SABR without too much risk or not
So the letter on my GP records says there is no mets to the pelvic area but now I am going for a planning scan
Oh well lets see what the outcome of that is
User
Bri , I remember J telling me something along the lines of , although we haven't confirmed you are metastatic we assume you are.
Hope all goes well next week.
Thanks Chris
Edited by member 14 Mar 2024 at 07:14
| Reason: Spelling
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Pass up and brewery comes to mind 🙄
"Life can only be understood backwards; but it must be lived forwards." Soren Kierkegaard
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Note that most PET scans are currently PET-CT scans, which is a PET scan image (which shows just hot spots) overlaid on a CT scan image, so they can see which organs are hot. This article is talking about PET-MRI scans which are PET scan images overlaid on MRI scans.
There are some PET-MRI scanners at the top treatment centres and private hospitals in the UK, but most PET scanners are PET-CT scanners.