Imaging Prostate Cancer
Posted: Nov 01, 2018
POSTED: November 27, 2018
Dr. Rodney J Ellis is a Professor of Radiation Oncology at the University Hospitals of Cleveland and a radiation oncologist at Case Comprehensive Cancer Center.
He spoke with Prostatepedia about how prostate cancer imaging is used in community settings and how it is impacting patient care.
Prostatepedia: Why did you become a doctor?
Dr. Ellis: I was seven when I told my parents I was going to be a physician when I grew up. They said, “Oh, Rod that’ll be really nice.” No one else in my family had gone to college, so they didn’t really expect that it was likely to happen.
I thought it was cool that my family doctor, who delivered my brother and me, had his wife in his office; they ran the office together. I thought that’d be really nice to work with my wife and run our own business.
Once I got to medical school, I realized that doctors do a lot of work that’s controlled by the insurance companies, and I became less enamored with primary care medicine. When my grandfather and an uncle developed cancer, I became more interested in oncology. It made me focus on how cancer impacts families. I had an opportunity to do a rotation in radiation oncology and met the mentor who taught me so much, which changed what I wanted to do in life.
That’s how I ended up in radiation oncology, initially working with monoclonal antibodies to image cancer and direct where you place radiation, either in the operating room with brachytherapy or intraoperative radiotherapy.
Over the last 20 years, as the field has blossomed, we’ve developed even better techniques for dose painting and giving high doses in regions. Largely, that’s been the focus of my academic career.
Dr. Ellis: Yes, especially since advanced imaging has come out and over the 20 years that I’ve been doing it. Sometimes, when I see a patient in long-term follow-ups, I think, “Wow, the advanced imaging we used actually predicted death from prostate cancer the day I saw him, but I just didn’t know it those ten years ago.”
When I look at the new imaging today and how it’s changing what we’re doing, I think we’re truly personalizing medicine.
I’ve seen numerous patients where I could determine whether their cancer was curable based on an image. If it is curable, does it change how you may image that patient? More often than not it may. For maybe one in three cases, it does nothing for you. You do the image, and the good news is it didn’t show any spread of disease. The bad news is it didn’t show any localization of the disease either. The test didn’t really help us; it just didn’t resolve the questions we had. For about two-thirds of my patients, it adds to their care. New data from ASTRO this last week shows in the Locate trial that even negative studies may have significant changes though, such as staying in surveillance versus aggressive local therapy if a study is negative.
Dr. Ellis: I use standard imaging, whether that’s bone scan, CT scan, or MRI. We’ve been very image-based in our approach to treat prostatecancer for many years. Currently, we use a lot of MR-based imaging and the functional imaging of MRI to look at these within the prostate gland. The dilemma for patients is whether there is any disease outside of the prostate gland. Much of the literature that I’ve published over the last two decades worked with the previous imaging agent that was FDA-approved for looking for spread of prostate cancer called ProstaScint. We’ve published on that with ten-year data showing that it was able to predict deaths from prostate cancer. It was useful for helping to select where to give higher doses within the prostate gland, when giving radiation to improve cure rates. That’s been largely improved upon with newer imaging agents, both the Axumin PET scan that is currently FDA-approved and the C-11 Choline that’s available at Mayo Clinic.
Worldwide, there’s a lot of interest in PSMA-based PET imaging. That is the same molecule that ProstaScint looked at years ago, only now the marker is looking on the surface of the cell rather than on the cytoplasmic, or internal surface, of the cell. This has greatly improved the PET agent over the previous generation products.
Dr. Ellis: Prostate cancer is non-uniform. All the cells are not going to be alike. They’re going to metastasize or develop different traits at different times. We can image some cells nowadays with Axumin PET. That looks at the synthetic amino acid that gets picked up more commonly by prostate cancer, but it may be applicable for some other cancers as well.
On the other hand, some cancers express PSMA, and may show up with a PSMA-based PET. Not all cancers show up with one or both, so we don’t know which agent is best for which particular patient.
The biggest limitation right now is that the only one that’s FDAapproved is Axumin PET. As a member of the National Comprehensive Cancer Network (NCCN) Prostate Board, I’ve looked at it and made recommendations to add that for standard imaging. The board has also made recommendations that, as newer agents come out, they should be considered as well.
Dr. Ellis: Well, I can give a great example. We had an add-on patient today who had been treated with hyperthermia in Germany, which progressed locally. We had treated him with proton therapy into the prostate, and for a while, he had responded to therapy, but his PSA had started rising.
Today, he came in for follow-up, and we did an Axumin PET this morning. I’m waiting for the results to be read by the radiologist. But on my review, it looks like he’s got a solitary metastatic focus that lights up in the right chest, adjacent to his airway. The question now is what to do in that setting. If you’ve got one site of metastatic disease that’s a clear distance from the prostate, the standard of care is to go on to hormonal therapy and give additional agents either orally or systemically for metastatic prostate cancer.
One of the opportunities these new agents may open up for us is to treat limited metastatic disease—or oligometastatic disease, which means that mets are present in only one, two, or a few sites—with radiation or other techniques to ablate that tissue and potentially prolong life for those patients.
Dr. Ellis: I think that Blue Earth, the company that’s been promoting that agent, is doing a great job of getting it out further into the community. The limitation with most nuclear medicine studies is the half-life of the agent. In other words, from the time you make it to the time you use it, it decays. The second it’s made, its half-life is in minutes, so it can only be used locally in the facility where it’s made. In Axumin’s case, it’s about three hours from the time before it becomes too weak to use in imaging.
They’ve got to start producing it in more areas and be able to get everyone who needs the image within a three-hour radius. The reality is that they may never be able to reach everywhere in the United States with that kind of a radius.
Dr. Ellis: It’s a little bit of both. It’s a fairly new agent, so I don’t think there’s a lot of patients who are aware of it yet. I’m a member of their speakers’ bureau, so I’ve got a bias. I can be honest and say yes, I’ve been working with the company to promote and let people know about it. They are still getting the word out, so a lot of patients don’t know about it yet.
I have started to see patients come specifically to ask if we do the test. I don’t know how many are coming directly to me versus how many are coming to our nuclear medicine department, where the test is done, but we are certainly using it much more frequently today than we were using previous imaging studies.
Dr. Ellis: Urologists, the primary caretakers for many of these patients, are becoming acutely aware of all the data that’s coming up worldwide on PSMA-based imaging with PET scan. They’re interested in nuclear medicine scans and cutting edge technologies to image their patients. What people aren’t really sure of is what to do with that information yet, so there’s more work that needs to be done to categorize the patients for the appropriate treatment.
Medical oncologists are starting to become aware now; certainly, the radiation oncologist is aware. Yes, there’s more work to be done teaching the physicians.
Dr. Ellis: Right. And we’re not sure whether it’ll impact every patient, that’s the problem. Is it going to be useful for every patient? Of course not. Will it change it in a large majority of patients so it becomes clinically significant? We think so. Right now, it’s only FDA-approved in patients that have had prior therapy. They have had prior radiation, surgery, or systemic therapy, and we have a reason to think that the therapy failed. Then, you image them.
But it is even more interesting to know, in the patient who is newly diagnosed, will these agents be used to help us see exactly where the cancer is located and to make a decision between surgery or radiation, and whether they will be used to make a decision about where to radiate.
Dr. Ellis: I believe the company is certainly interested in investigational studies in answer to that question. I would have to defer to them about which studies are currently open and active.
Dr. Ellis: That is a huge part of what I do. And the best way to do that is publications. Publications get out there, and they don’t go away. People read them, and they learn about these studies from trusted sources. But until publications can get done, going out and doing person-to-person education or webinars are other ways to get the word out.
Dr. Ellis: Both. I think there’s an educated group of patients out there now, more so than 20 years ago, when I started my practice. It’s probably information from the internet. Everyone has access to the internet. If you search for prostate cancer and start spending some time, you’ll come across the imaging data. They bring those questions in.
Dr. Ellis: Yes. We’re wrestling with all the information that’s coming and how to best assimilate all that information for an individual patient.
Dr. Ellis: I would like to see more people lobby to get advanced imaging approved for newly diagnosed patients. Unfortunately, many of those patients don’t have access to it, and I’d like to see the people who are doing clinical research present their data to help support that, if there is emerging data to do so.