Tag: imaging

Month 184 – PSMA Explained & Next Steps

On By DanIn Hormone Therapy, imaging, Prostate Cancer4 Comments

After last week’s PSMA PET scan, I did a little more digging into how the scans work, and why they don’t work for 10% to 20% of patients.

Prostate specific membrane antigen (PSMA) is a protein that’s found in healthy prostate cells, and it continues to exist in prostate cancer cells in most, but not all, cases.

PSMA in Imaging

Researchers found a way to attach a radioactive tracer to the PSMA proteins which would light up when seen in a PET scan, indicating the presence of cancer. Gallium-68 is the most commonly used tracer, with fluorine-18 also being used.

When the tracer is injected into the patient, it seeks out cells that have expressed the PSMA protein and attaches to them. The PET scanner then looks for areas where there is a build-up of the tracer to indicate where the cancer is located.

I’m going to use a grossly over-simplified analogy based on my reading as a lay person.

We all know that magnets are attracted to steel or iron. Imagine that the cancer cells with the PSMA protein are small steel ball bearings, and the radioactive tracer is a bunch of tiny magnets. Inject the magnets into your system, and they go in search of the steel ball bearings. When they find them, they attach, and the PET scan can see where all the magnets are located.

But for those patients whose cancer cells do not have the PSMA protein, that essentially means that the cancer cells are plastic balls, and the magnets that were injected will never attach to them. The PET scan won’t see any build-up of magnets/cancer cells.

Based on my experience with four PSMA PET scans, I believe that I’m in that 10% group and that my cancer cells do not express the PSMA protein—they’re the plastic balls.

PSMA in Treatment

In addition to using PSMA positive cells for imaging purposes, researchers have also recently developed a treatment that uses the PSMA positive cells. It goes by the brand name Pluvicto, but also known as Lutetium-177–PSMA-617.

It’s only used on patients with castration-resistant prostate cancer that have PSMA proteins.

The difference between using gallium-68 or fluorine-18 and lutetium-177 is that the lutetium is a radioactive material that attaches to the PSMA protein cells and delivers beta particle radiation to kill the cells.

This means that for those patients whose cancer doesn’t express the PSMA protein, this treatment option would not be available.

Alternative Imaging

On the good news front, there are other imaging options out there, one of which is Axumin (18F-fluciclovine). Instead of targeting PSMA in the cancer cells, it looks at the amino acids.

Axumin scans aren’t as sensitive as PSMA PET scans, but they are more sensitive than choline-11 scans.

At my current PSA level (2.52 ng/mL), the Axumin scan should have a decent chance of finding something.

In a conversation in a prostate cancer forum, I learned that one patient had used the gallium-68 tracer for his PSMA PET scans with the same results as mine, but they switched to PYLARIFY (piflufolastat F 18) as the tracer (which also attaches to the PSMA) and found four lesions using the different radiotracer. I know that one anecdotal case doesn’t mean much, but it’s something I can ask my team about.

Skip Imaging?

You may recall that, at one point, I had conflicting guidance from the urologist and oncologist on when to start androgen deprivation (hormone) therapy (ADT). One said when we saw metastasis, and the other said when my PSA hit 2.0 ng/mL. Clearly, I’ve passed the 2.0 threshold with my latest PSA results.

I went back and recalculated my PSA doubling time using only the last four values dating back to 10 March 2025. (The fourth and fifth values that I used before are 0.94 (January 2025) and 0.95 (March 2025), so having them so close may have skewed the results a little. When I used all five data points, my PSADT was 10.1 months; when I use the last four data points, it’s 8.9 months.

Given I’m past the PSA threshold (for one doctor) and the fact my PSADT is less than 10 months, I’m also wondering if there’s any value in continuing in the efforts to try and find the lesions. Or is is better, given how my PSA is increasing, to go ahead and just resign myself to the fact that I have micrometastases someplace and start the ADT sooner rather than later? In the time that it takes to schedule another scan, regardless of the type, my PSA could be well over 3.0 and even pushing 4.0.

That leads me to another question. If we do start the ADT and it knocks my PSA down to <0.1 like it did when I had it for salvage radiation therapy, does that mean that scans wouldn’t be able to locate the cancer while on ADT?

To my way of thinking, knowing where the cancer is at is important, even if it means letting the PSA run unabated for a short while longer. But what the hell do I know? I’m all ears for experiences from others that may have been in the same or similar situation.

Summary

Again, this is my lay person interpretation of things that I’ve researched, so please take this with a pound of salt. If you know I’m wrong on my interpretation, please let me know and provide references as to why I’m wrong. I want to learn.

You can rest assured, though, that this will be a part of my conversation with my team on 24 March.

Stay tuned for more.

Be well.

Header image: Desert wildflowers, Anza-Borrego Desert State Park, California

Imaging Alternatives For PSMA Negative Prostate Cancer Patients

On By DanIn imaging, Prostate CancerLeave a comment

Here’s another informative video from the Prostate Cancer Research Institute for the ten percent of patients for whom PSMA PET scans may not work.

If I go for a third PSMA PET scan later this summer, and it fails to show anything at an even higher PSA level than my first two inconclusive scans (0.22 ng/mL and 0.37 ng/mL), I may find myself in that category.

I’ll provide my normal monthly update next week after my visit to the urologist on 14 May.

Day 4,830 – PSMA PET Scan

On By DanIn imaging, Prostate CancerLeave a comment

PSMA PET scan No. 2 is behind me.

This was different from and easier than the first one. That’s because the VA just did a PET scan today, whereas my scan at UCLA included a CT scan on top of the PET scan.

That fact really didn’t occur to me until all was said and done. I’ll have to ask the doctor about the đifferent approaches.

In any case, today they juiced me up with Gallium-68 shortly after arrival. About 45 minutes later, I was on the scanner table ready to go. I barely felt the table move me through the scanner, and it took about 45 minutes to complete the scan.

Of course, the technician wouldn’t give me any sneak peak insights. “The doctor will interpret the scan.” I expect it could take a week or so for me to see any notes in my online records.

Again, even with my PSA closing in on 0.40 ng/mL, there’s only about a 50-50 chance it will give us any useful information at that PSA level. (As a refresher, my PSA going into the UCLA scan was 0.22 ng/mL.)

More to come.

PET Imaging Video from Dr. Eugene Kwon

On By DanIn imaging, Prostate Cancer5 Comments

Here’s a very informative 23-minute video for both the newly diagnosed and those of us who have been playing with this for a while. It gives a good overview of prostate cancer, imaging in general, and PET imaging specifically.

Dr. Kwon is from the Mayo Clinic and, as I recall, was an early advocate of using PET imaging in identifying and treating oligometastatic prostate cancer.

This video was from the Prostate Cancer Research Institute (PCRI) YouTube channel. I’m not sure when Part 2 will be released.

Day 4,037 – Insurance Rationale

On By DanIn imaging, Prostate Cancer1 Comment

Over the weekend, I received a letter from my health insurance company explaining the denial of covering the cost of the PSMA PET scan. This differs from what the representative told me via email (UCLA didn’t send all of the necessary paperwork) and carries far more weight, as it appears that a medical review was done. The redacted section below is the name of my insurance provider.

In a nutshell, because my PSA is 0.22 ng/ml, it doesn’t reach their threshold of 1.0 ng/ml, they deem the scan “not medically necessary” and won’t cover the cost.

The insurance company may have a limited point in their comment, “Use of this study would [not] improve the outcome” with my PSA level being so low. Realistically, the chances of the cancer metastasizing while waiting for the PSA to go from 0.22 to 1.0 are miniscule—especially with my PSA doubling time—and the treatment options would likely be the same: Salvage radiation, perhaps with hormone therapy as well.

However, the insurance company is missing the larger point: The whole purpose of having highly sensitive, highly specific scans like 68-Ga PSMA PET is to locate cancer early so that you can come up with an effective treatment plan that hopefully does, in fact, have a positive impact on the outcome and survival.

My urologists were supportive of getting the scan, so I’ll see if I can’t get them to help convince my insurance company through a formal appeal that this is, in fact, medically necessary.

As far as the scan itself, it’s less than 24 hours away. UCLA Department of Nuclear Medicine did remind me that I have to fast for at least six hours prior to the scan, drinking only water. No juice, no coffee, just water.

I’ll let you know how it went.

Be well!

Watch: Current Status of PSMA Diagnostics

On By DanIn imaging, Prostate Cancer3 Comments

Here’s a good overview of PSMA diagnostics by Dr. Calais, one of the UCLA doctors involved with getting 68Ga-PSMA-11 PET approved by the FDA. It’s a bit on the technical side, but it does show the strengths and limitations of the imaging technique.

Day 3,892 – Scan-a-Palooza

On By DanIn Prostate Cancer, Recurrence6 Comments

Let the radioactive fun begin!

I was able to schedule my bone and CT scans this morning with considerable ease. In fact, things will happen much sooner than I thought they might. My CT scan is scheduled next Wednesday, 14 July, and my bone scan is scheduled Friday, 23 July.

I have to go for some pre-scan lab work tomorrow afternoon to ensure that my kidneys are working fine and won’t be damaged by one of the contrasts.

I haven’t given up on the Ga-68 PSMA PET scan. In fact, I wrote my health insurance company an email about 4:30 a.m. as I tossed and turned. (Last night was hell. If I slept more than 2 hours—non-consecutively—that was about it.) They tout having a response within 2 business days, so we’ll see if they come through with that.

UCLA is out of network for my insurance company, so I’d have to cough up 40% of the cost if they’re going to cover it at all. I’m okay with that. (For my overseas readers, welcome to U.S. health care systems!)

So that’s the latest and greatest. More to come, I’m sure.

Be well!

Watch “Biochemical Recurrence After Local Therapy: Assessment and Management” on YouTube

On By DanIn Prostate Cancer, Recurrence3 Comments

This is a really interesting (at least to me) video out of the University of California San Francisco (UCSF). Remember that UCSF and UCLA were the two institutions that did considerable work to get the Ga-68 PSMA PET scan approved by the Food and Drug Administration in December 2020.

First, at the 3:04 minute mark in the video, he presents the number of positive scans by PSA level. Interestingly, he references the same study I posted earlier. What differs in this presentation from the other one I posted is that this looks at PSA values <0.2 and from 0.2-0.49, whereas the other study just looked at positive scans for PSA values <0.5. However, something seems off between the two.

In the original study, it showed a positive detection rate of about 38% for PSA values <0.5. In this video, however, the chart appears to show a positive detection rate at the <0.2 PSA level somewhere north of 40%, and a positive detection rate at the 0.2-0.49 PSA level somewhere north of 50%. Perhaps he wasn’t all that skilled at making bar charts in PowerPoint, but something is amiss.

Where I’m encouraged is that it appears that they are, in fact, able to detect cancer at my PSA level or even lower. The only question is, at what rate? I’ll stick with the one in three value for now, which is still better than zero.

I did email one of the doctors on the team at UCSF, and his response was:

There are no guarantees, but there is a chance that a PSMA PET could detect a site of recurrence with a PSA of greater than 0.2. The chance of detection usually increases as the PSA goes up.

Not exactly a ringing endorsement of his own product, but I think that’s more to couch expectations because this is so new and even he is still trying to figure it out. (I admit, I was surprised that he even responded, so I’m thankful for that.)

I’ve got a good list of questions ready for my appointment on Tuesday, and I’m sure I’ll spend some of this holiday weekend adding to it and refining it.

Stay tuned for more.

Watch “Rising PSA: How Soon Should You Get a Scan? | Thomas Hope, MD & Mark Moyad, MD | 2021 PCRI” on YouTube

On By DanIn Prostate Cancer, Recurrence, Treatment1 Comment

Wow. This could not be more applicable to my current circumstances and certainly gives me food for thought.

Watch “2021: PSMA and Prostate Imaging | Dr. Thomas Hope | 2021 Moyad + Scholz Mid-Year Update | PCRI” on YouTube

On By DanIn Recurrence, Research1 Comment

I came across this video highlighting Ga68 PSMA PET imaging from the doctor at the University of California San Francisco who helped with developing this imaging technique. It’s a bit long and a bit technical in some places, but gives a good overview.