So, this is a slide I got from Jeremy a few years ago, which I think really, really summarizes this entire talk, is that clinicians who manage prostate cancer, and radiologists and nuclear medicine docs who read our imaging, we really have different perspectives. For us as clinicians, the fundamental problem is we want specificity. We want to know what's a true positive, we want to reduce false positives. And we would trade off sensitivity for specificity. That is, we would accept lower sensitivity of a diagnostic test if it increased specificity. So, we want to know, how do I treat this imaging finding? Is it real? Do I withhold potentially curative treatment based on an imaging finding? So, if there's a bone met, or a lymph node met that's suspected, should we withhold surgery or primary radiation to treat that? Or do we overtreat a finding that actually may not be cancer?
But the perspective of a reading nuclear medicine doc or radiologist may be different. Maybe I don't want to miss anything. I need to back myself up in case some lawyers come after me down the road. I'm uncertain about what this finding means, but I've got to report it anyways. And how do I communicate this in a way that is helpful to the clinician? So, I think that this lays out the fundamental difference, and we have this discussion. That's why multidisciplinary management is so important, because the ability to discuss these issues with my nuclear medicine colleagues has made all the difference here. So, these are some common scenarios. Lesions with low uptake. We get that literally every day. Are they true or false positives? Are they being overcalled? We see low PSMA uptake in a slightly enlarged lymph node in men with newly diagnosed or recurrent prostate cancer.
We see variable PSMA uptake in one or more rib lesions. We see low PSMA uptake in locations that are not typical for prostate cancer, mediastinal or inguinal lymph nodes very commonly. We see indeterminate findings in organs generally not thought to be associated with prostate cancer. Are they prostate cancer, or are they non-prostate pathology? We see a lot more nowadays of low or even negative PSMA uptake in incidentally found lung nodules. We found some of them actually to be positive for prostate cancer, others to be negative. How do we discriminate? We see uptake in other organs as well. Obviously, PSMA is expressed in neovasculature of other tumor types, and so PSMA imaging may pick up other tumor types. And then we see a lot of discordant findings. Are these also true versus false positives? Uptake in a bone lesion without a CT correlate, or a multifocal signal in the prostate that's discordant with the MRI. This is important for us. We clinicians, urologists, trying to make decisions about focal therapy versus radical therapy. So here's some cases, some good ones, some bad ones. So, this is a guy that I saw back yesterday, 52-year-old, Gleason grade 3+4 in his biopsy.
He had a PET as part of his diagnostic workup. And this PET showed the primary tumor, but also showed a focal low PSMA expression in a small lymph node at the left iliac bifurcation, measuring seven by 10 millimeters, with an SUV max of 2.7. The impression of the radiologist is that this is suspicious for nodal metastasis. As a clinician, I'm thinking, okay, this is an area where prostate cancer metastasizes to, common iliac is quite common, but the guy has a low-risk disease. I can't remember what his Decipher score was, and I wouldn't have expected to see metastatic disease. So, do I ignore this and not offer him surgery, or do we go ahead and treat him? I decided to treat him. He opted for surgery. He actually had a Gleason 7 tumor, T2, 20 negative lymph nodes as part of an extended lymph node dissection, including the common iliacs. Obviously, this was a false positive, and his PSA now is undetectable. So this is a very common scenario where these low SUVs, they're called, sometimes they're called, sometimes they're not.
Here's a case which I think was better handled. A 58-year-old man with a grade 3 cancer on his biopsy. The reading showed prominent sub-centimeter short axis bilateral external iliac and right inguinal lymph nodes. Inguinal lymph nodes very uncommon for prostate cancer with low activity. The radiologist recognized this and said suspected reactive given the distribution. So, really recognized in the context of this patient, is this likely to be a true or false positive? So, we went ahead. He also had some subtle rib lesions, which we also commonly see. Also, thought to be more likely not cancer than cancer. He also underwent surgery, also undetectable PSA. So that's a case of a report that was somewhat more useful to me as a clinician than the other one, looking at things from my perspective. Here's another case. This is a guy with recurrent prostate cancer. He had surgery back in 2019. He had recurrence, had radiation to the prostatic bed, because at that time his PSMA PET was negative. PSA continued to rise. And actually, yesterday, was 0.9. So he had a PSMA PET. And what they found is basically nothing clearly positive, but a bunch of indeterminate findings.
So a focus of low expression in the posterior right eighth rib with an SUV max of 2.2, and one in the lateral left seventh rib with an SUV max of 2.1 and also a ground-glass nodule in his lung. What to do? There's really no guidance in the report about the likelihood that it might be a true positive or common false positive that we see. Not clear what to do about this patient. Case number four, guy with Gleason 9 disease. This is prior to surgery as well. There's faint PSMA uptake in the left lateral second rib, but here the radiologist interpreted this as likely benign. Same SUV as the other person, the other patient I just showed. To me, this is a good report because it highlights that this is likely to be negative, and shouldn't really impact our primary decision-making. All right. How am I doing time-wise? And then one more case is a 70-year-old man who had cryotherapy.
This is a patient of Dr. Brisbane's, he saw just a couple days ago. At the time of his cryotherapy, he had a single lesion, PI-RADS 4, and basically an initial PET scan was negative other than some mild uptake in the bilateral mid-gland. Post-treatment, he's now being surveilled. His PSAs have declined over time, but as part of a protocol that he's on, he underwent PSMA PET. And this showed history of favorable-intermediate prostate cancer status post cryoablation with new small scattered foci of low PSMA expression and bilateral ribs, at least one lesion associated with sclerosis and new since prior, concerning for metastatic disease. For example, right posterior rib. What to do about this? We would not anticipate this man with a relatively low-risk disease. Treated negative biopsies post-cryotherapy is going to have a new lesion in his bone. Most likely this is a false positive, but obviously if you're reading this, as a clinician who doesn't have a lot of experience, you're going to start chasing after this type of thing.
So this is not that uncommon that we see this. So, in the interest of time, I'll skip those last two cases and talk about maybe some solutions. Probably getting to the end of this slide, the most important thing is education. Education of nuclear medicine and radiologists, and education of urologists, medical oncologists and radiation oncologists. These are UCLA reports. I can tell you the vast majority of reports I get now are from outside institutions, and they're all over the map in terms of the quality of the reports, the interpretation of the report. And I see the same thing from physicians who don't have tremendous amount of expertise in interpreting this. So A is to integrate standard reporting features of lesions with some interpretation needed to guide clinical care, educate clinicians, both radiologists as well as clinicians who treat patients, to know what's common and what's not common, to use structured reporting. We've got obviously staging systems like Primary or Promise V2, but we need to really educate clinicians what these mean, and we need to use them. Some ideas explicitly list the size and PET signal of indeterminate lesions, provide an opinion of low or high suspicion to help guide a clinician, avoid vagueness whenever possible. When I was in training many years ago, we used to call nuclear medicine unclear medicine. We don't want to go back to those days.
We really want it to be a clear medicine, not unclear. Provide a differential diagnosis given the context of the patient's history. So it behooves doctors to provide the proper history to radiologists and nuclear medicine people, radiologists, so that they can interpret the imaging in light of the context of the patient's disease. So, if a patient's got a grade 1 or grade 2 cancer, unlikely to have metastatic disease, don't overcall something that's clearly likely to be a false positive. Suggest actions when possible, such as a confirmatory biopsy or imaging. And above all, communicate between the treating physician and the nuclear medicine and radiologist docs, and multidisciplinary discussion. I think this is really the key to improving the quality of our reports, as we improve the quality of our imaging over the coming years. And there are a number of reports in the literature about how to go about doing this, such as this one from European Urology last year by Jeremy and others. All right, hopefully I'm on time, and we'll finish there. Thanks.