In the hour or so since my last post, my scan results were posted online:
“No evidence of recurrent prostate cancer or metastatic disease.”
<Sigh>
Needless to say, I have mixed emotions about these results.
I just want an explanation so that we can figure out next steps. After four scans with the same results, I’m of the mindset that I’m in the 10% of patients for whom PSMA PET scans don’t work.
You can bet I’ll be talking about other imaging options during my upcoming appointment, as well as any other plausible explanations for what’s going on.
At this point, I’m tired, frustrated, and stymied.
Dan's Journey through Prostate Cancer 
I thought that if you were already getting a PSA reading it would be the sensitive “type?” After all, you’ve been tracking this with a PSA reading for years, right?
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Hi, Jack,
I believe you’re confusing PSA with PSMA.
You’re right that I’ve been tracking my PSA for years, and there are PSA tests with varying sensitivity. My PSA tests have never been the ultra-sensitive tests that you hear about.
Prostate Specific Membrane Antigen (PSMA) is a separate feature of a cancer cell.
“PSMA is very specific protein often found on the surface of prostate cancer cells. But not every prostate cancer has PSMA.”
It’s the “not every prostate cancer has PSMA” part that I’m beginning to believe applies to me.
PSMA PET scans need the PSMA to be present on the cancer cells in order to see them. If there’s no PSMA, the scan won’t see the cancer.
Not having PSMA present can also exclude you from the radiotherapy treatment, Lutetium-177, because it needs PSMA to be present to work.
Here’s a good summary from the Mayo Clininc:
https://mcpress.mayoclinic.org/advanced-prostate-cancer/psma-targeted-therapy-how-are-radiopharmaceuticals-used-to-treat-advanced-prostate-cancer/
Hope that helps.
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Hi Dan. No, I do understand they’re two different things. I was just thinking that I heard of case once where a someone’s PSA was zero literally but the doctor (during a DRE exam) felt a bump. He told him to get it checked out and it was cancer which eventually got him. I know that there are rare cases like this. I was assuming that if you’re showing a PSA reading that it was going to be sensitive then, but I guess there’s more to it.
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Wow, seems like a pretty good result to me. I understand that doc’s are now relying on PET scans, rather than PSA, as they are much more accurate. Let’s hope this is the case!!
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Hi Phil,
If I knew 100% that my prostate cancer was expressing PSMA, you’re right: those are great results.
But, in about 10% – 20% of cases, the cancer cells don’t have the PSMA protein. If there’s no PSMA present, the PET scan will never see it.
I think I may be in that group, and that’s where my frustration is coming from.
This article talks about it more in-depth:
https://mcpress.mayoclinic.org/advanced-prostate-cancer/psma-targeted-therapy-how-are-radiopharmaceuticals-used-to-treat-advanced-prostate-cancer/
Best to you,
Dan
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