PET Scans and Disappointments - 035
I want to give you a quick update before I dive into this next topic. I feel good, have more energy, and have gained about five pounds of lean body mass. My workouts, which are a crucial gauge of my overall health, are almost back to my baseline regarding intensity and recovery. My gut function is virtually normal, with only a few intermittent days where I have bloating. Overall, I’m feeling great!
My last PET scan
My last positron emission tomography (PET) scan was on May 30, 2023, and showed no evidence of malignancy despite a prostate-specific antigen (PSA) of 63.21. I've had other PET scans that were normal despite an elevated PSA, but those scans were when my PSA was only mildly elevated.
People ask me how a PET scan can be normal despite a high tumor marker indicating ongoing prostate cancer. Keep in mind my PSA should be zero, given that a surgeon removed my prostate. So, any elevation of PSA in my blood work suggests residual cancer in my body.
I've written about PET scans for prostate cancer in newsletter 024, where I discuss how different PET scans measure various aspects of the tumor's molecular components. Prostate cancer is highly heterogeneous, meaning there can be multiple tumor types even in the same individual, and this tumor variability also reflects variability in these molecular components.
If you use a PET scan that measures a particular tumor component, but your tumor's component differs from what the PET scan measures, you might have a normal PET scan despite having tumor cells in the body.
In addition, when you have a small number of tumor cells in your body, a PET scan is more likely to be normal. However, a PSA of 63.21 indicates many tumor cells in the body.
Normal PET scan with a high PSA
So, how did I have a normal PET scan with a PSA of 63.21? We'd have to go back to the PET scan I had on December 15, 2022, for you to understand what happened. The December scan was a Pylarify PET scan, which measures a protein on the tumor's cell wall called prostate-specific membrane antigen (PSMA).
Four types of PET scans approved by the Food and Drug Administration (FDA) measure PSMA levels. They differ by the tracer they use, but all detect PSMA.
PSMA PET scans carry the "latest and greatest" label for assessing prostate cancer, which can be "great" if used in an appropriate clinical context. Over 80% of prostate cancers produce PSMA, but not 100% of them.
One must consider the individual and their unique disease state to help decide on which PET scan to use in prostate cancer. Considerations include whether they've undergone treatment, prior PET scan results and whether they are castrate-sensitive versus castrate-resistant.
Individualized assessment is part of precision medicine, which is essential for tackling highly heterogeneous prostate cancer.
My December 2022 Pylarify scan showed I had approximately six lesions in the lymphatic chains lining both sides of my aorta from just below my diaphragm to the top of my pelvis. I underwent proton beam therapy for seven weeks starting in January 2023, explicitly targeting these sites.
The follow-up May 2023 Pylarify scan showed no malignancy, indicating the proton therapy had eradicated the PSMA-producing tumor cells. The PSA had risen slightly from 57.64 to 63.21 despite a normal PET scan after proton therapy. This rise in PSA indicated I had other types of prostate cancer cells in my body that weren't producing PSMA.
The May 2023 PSA of 63.21 dramatically increased to 117 in August 2023, which was not surprising as this was during the period I was experiencing small intestinal bacterial overgrowth, fungal toxin exposure, and reactivation of Epstein-Barr virus.
The August to December rise in PSA significantly slowed from 117 to 135, suggesting that tackling the EBV and gut dysfunction and toxicity helped my body get a better handle on the cancer cells.
Confirmation bias
So now that it's time to undergo another PET scan, should I have another Pylarify scan? My answer is "no" based on my clinical data since May. If we do another PSMA PET scan now, we'll likely miss at least half of the tumor cells based on a normal May PSMA PET scan with a PSA of 63.21.
So when I met with my radiation oncologist to discuss this, I was surprised he still wanted to go with a Pylarify scan. I asked him why that was his choice, and he told me he thought the Pylarify scan was the "best" scan and based that on an anecdotal story about one of his other prostate cancer patients.
He told me another prostate cancer patient had a mildly elevated PSA level and requested the Pylarify scan. He said that he didn't think a PSMA PET scan would show anything, given how low his PSA was, but was surprised that it demonstrated several lesions.
What did that patient's story have to do with me, and how did it justify why a Pylarify scan is appropriate for me now? Nothing, and it didn't.
That patient was in the very early stages of prostate cancer. Our tumor biology is not the same. Most importantly, I had a prior Pylarify scan that was normal despite a high PSA level, and that patient did not.
My radiation oncologist's rationale is an example of confirmation bias, a tendency to process information by looking for or interpreting information consistent with his beliefs. He truly believes PSMA PET scans are the best type of PET scans for prostate cancer. They can be, but only in the proper clinical context.
The choice
Based on his answer, I told him I didn't think a Pylarify scan was appropriate, so we discussed other options. He told me the next best test would be a Choline C-11 PET scan. I didn't ask him why that one instead of an Axumin scan, which I've had before.
I don't know of any studies that have compared the Choline C-11 scan to the Axumin scan for prostate cancer, but I agreed to the Choline scan because I wanted him to make the decision. And I didn't want to come across as the problem patient.
Disappointment
I found the next thing that happened quite disturbing. My radiation oncologist said he had reviewed my May Pylarify scan, and now he feels there is a malignant lesion in the prostate bed.
I have had so many disappointing experiences in this prostate cancer journey that I didn't even blink an eye. I sat silently while he pulled up the scan on his computer monitor and showed me the small area he was talking about.
He explained that he had previously thought this spot was a slice through the ureter containing the radioactive tracer as the kidneys were eliminating it. Now, he believes it's not the ureter but a tumor in the prostate bed.
I didn't ask any questions about why he hadn't seen this before and how the radiologist who over-read the scan also missed it. I also didn't ask him if he had reviewed it, looking for something in the scan to justify doing another Pylarify scan.
Keep in mind this is the second time my radiation oncologist has retracted a PET scan result done in their facility and read by their radiologists. The first time was when he reviewed my April 2021 Axumin scan and disagreed with the results.
I wrote about this in newsletter 021, where the radiologist had interpreted the Axumin scan as "Focal increased uptake in or adjacent to the anterior wall of the rectum and the prostate bed as described above. Worrisome for recurrent tumor."
He disagreed and told me it was a false positive due to the dense musculature of the anal sphincter. Now he's retracting another PET scan from six months ago, saying that it wasn't normal but that there is evidence of a tumor in the prostate bed.
Checks and balances?
In this facility, the doctor reviews and interprets the scan with you immediately after the test and then has one of their radiologists over-read the scan for accuracy. Checks and balances. Right?
One retraction, okay, I understand mistakes happen. But two? So, who is misreading the scans, the radiation oncologist, the radiologist, or both? These are the thoughts that go through your head.
Does this change anything? No. Even if there is a small asymptomatic tumor in my prostate bed, I can't get any more radiation to my pelvic area, and I'm not going on androgen deprivation therapy again.
Gratitude
I sincerely love my radiation oncology team and their facility and staff. I have been working with them since 2018, have undergone two different types of radiation therapy through them, and have felt safe in their hands. Most importantly, they always listened to my input and never came across as authoritarian. I’m grateful for this.
As a physician, I know we are human and can always do better. I've made my share of mistakes in my medical career. But as a patient, it feels different. Good lesson.
I was planning to include how a change in my health insurance necessitated a hunt for the most affordable PET scan, but since this newsletter has gotten a bit long, I'll save that for the next one.
Even though I'm familiar with the health insurance billing game, I was shocked at the price differences for PET scans from facility to facility, including the "non-profit" Mayo Clinic.
Until next time, stay well, and much love.
Keith
I would try ivermectin and Fenbendazole. What do you have to lose at this point.
Good luck from Chemo Freak and Ratzo. Cancer is shit!