The Intricacies and Potential of PSMA PET/CT in Modern Salvage Radiation Planning - Philipose Mulugeta
November 6, 2023
Philipose Mulugeta presents the SNMMI Case of the Month, focusing on the use of PSMA PET/CT for salvage radiation planning in the context of biochemical recurrence. The case involves a 73-year-old patient with a history of radical prostatectomy in 2017, salvage radiation therapy in 2021, and a rising PSA trend. Despite previous negative imaging results, the patient underwent a PSMA PET/CT, revealing evidence of metastatic disease in various nodes. This discovery ruled out salvage radiation, leading to the patient's referral to medical oncology and initiation of dual ADT therapy. Dr. Mulugeta highlights the foundational data for Pylarify approval, referencing the CONDOR trial. The trial demonstrated PSMA PET/CT's high detection rate, especially in biochemical recurrence, and its significant impact on treatment strategies. Dr. Mulugeta concludes by emphasizing PSMA PET/CT's superiority over other modalities in detection rate and its patient-friendly nature.
Biographies:
Philipose Mulugeta, MD, Clinical Director, Nuclear Medicine Imaging & Therapy, Associate Professor of Clinical Radiology, University of Pennsylvania, Philadelphia, PA
Biographies:
Philipose Mulugeta, MD, Clinical Director, Nuclear Medicine Imaging & Therapy, Associate Professor of Clinical Radiology, University of Pennsylvania, Philadelphia, PA
Read the Full Video Transcript
Philipose Mulugeta: Hello, everybody. Thank you for joining for the SNMMI Case of the Month. I want to present case six, PSMA PET/CT for salvage radiation planning and in the setting of biochemical recurrence. Thank you to the SNMMI Value Initiative for this series and the opportunity to be here with you.
We're going to jump into the patient background. It's a 73-year-old patient with a history of radical prostatectomy in May of 2017, followed by salvage radiation therapy for biochemical recurrence in 2021, and now with a continued rise of PSA. As you can see from the PSA trend, it goes from sub one to a little bit above one and almost two over the six to eight months after the last treatment, and was currently on observation from the time of referral to radiation oncology for discussion of additional opportunities for salvage radiation.
The previous imaging workup included a negative PSMA PET/CT in September of '21 and a negative multi-parametric MRI in April of 2023, and finally under underwent C-11 choline PET/CT by an outside facility in April of 2023. That was also interpret interpreted as negative for recurrent or metastatic prostate cancer.
The patient was seen by radiation oncology in the clinic and was deemed a candidate for radiation as long as it was outside the previous sites of treatment. Outset Outside records were requested, and at the time of review after the patient was discharged from the clinic, a repeat MRI of the prostate, a PSMA PET/CT, and a referral to medical oncology for ADT management were initiated.
All right. The patient's MRI 3T was performed with an anatomy series axial T2. You can see that there is no evidence of recurrent disease in the prostatectomy bed here, and then we can move on to the dynamic post-contrast series performed with high temporal resolution looking for early enhancement in the bed here and see if there's recurrent disease, which there wasn't. The exam was correctly interpreted without recurrence.
The PSMA PET/CT with the brand name Pylarify was performed about a month later. Here's the rotating MIP of the image. Here's the CT image. CT image fused with the PET/CT data. There's a streak artifact in the CT portion of the study, but the PET/CT remains diagnostic. There's the image of the prostatectomy bed outlined in green. Again, no evidence of radiotracer avid or recurrent disease in the prostatectomy bed.
Review of the additional portions of the exam does show evidence of metastatic disease in-normal-sized retroperitoneal nodes with intense radiotracer uptake. You can see them on CT, on the fused CT PET image, as well as the static MIP here. Similarly, in the posterior mediastinum, there are normal-sized nodes with intense radiotracer uptake. And finally, a left supraclavicular lymph node, a very small node under five millimeters with intense uptake. You can see here where the right arrow is. This is in contrast to the comma-shaped normal cervical ganglia that are sometimes pitfalls in this region and generally have a low-level paired uptake, in this region and can be distinguished from pathologic lymph nodes.
The patient impact here is very clear. The patient has nodes outside the salvage bed, precluding salvage radiation. The patient was referred to medical oncology, started with dual ADT therapy, and had a good response to the PSA trend at the last check in the patient chart.
It's always good to see the foundational data for the Pylarify approval, one of them being the CONDOR trial, a phase three trial enrolling about 113 men with BCR based on Astro or Phoenix criteria. Patients were not on active treatment at the time of PET/CT and had to have either negative or equivocal results from structural imaging, most commonly with CT/MRI or bone scan. A PSMA PET/CT was performed with central blinded reading, followed by a standard of truth, which was either follow-up imaging, biopsy, or assessment on biochemical grounds to confirm the true positivity of the scan.
There are many outcomes from the trial, but perhaps the easily understood one is the detection rate by PSA level. It's a very robust test where detection rates do go up clearly with PSA values, with greater than 90% positivity above a PSA of five in the setting of PSA recurrence, but even in low PSMA realms under .5, where CT and MR, we know from historical data, have very low positive rates. It's about 30 to 40%, which is really good and a substantial improvement over structural imaging.
Overall, 80% of all patients had positive PET/CT results, impacting patient changes in about 73% of those patients. Some examples include a change from salvage radiation to systemic therapy, from systemic to attempted salvage local control, to directed therapy, and then finally, some patients who changed from treatment plans to observation.
In the CONDOR trial, there were no significant side effects. The limitations, of course, are we don't have any long-term data to see what result changes, as directed by PSMA PET/CT, how they impact the change in a patient's prognosis and other outcomes.
In summary, I want to say PSMA PET/CT has the highest detection rate of any modality that we have currently in radiology and nuclear medicine, especially in the setting of biochemical recurrence. It does have impacts on treatment strategies, and patient counseling. It should definitely replace low-value imaging in low PSA values. It is an extremely patient-friendly exam with minimal patient preparation and less radiation than CT and bone scans combined.
I want to thank all the SNMMI prostate cancer outreach working group members for the series and this opportunity.
Philipose Mulugeta: Hello, everybody. Thank you for joining for the SNMMI Case of the Month. I want to present case six, PSMA PET/CT for salvage radiation planning and in the setting of biochemical recurrence. Thank you to the SNMMI Value Initiative for this series and the opportunity to be here with you.
We're going to jump into the patient background. It's a 73-year-old patient with a history of radical prostatectomy in May of 2017, followed by salvage radiation therapy for biochemical recurrence in 2021, and now with a continued rise of PSA. As you can see from the PSA trend, it goes from sub one to a little bit above one and almost two over the six to eight months after the last treatment, and was currently on observation from the time of referral to radiation oncology for discussion of additional opportunities for salvage radiation.
The previous imaging workup included a negative PSMA PET/CT in September of '21 and a negative multi-parametric MRI in April of 2023, and finally under underwent C-11 choline PET/CT by an outside facility in April of 2023. That was also interpret interpreted as negative for recurrent or metastatic prostate cancer.
The patient was seen by radiation oncology in the clinic and was deemed a candidate for radiation as long as it was outside the previous sites of treatment. Outset Outside records were requested, and at the time of review after the patient was discharged from the clinic, a repeat MRI of the prostate, a PSMA PET/CT, and a referral to medical oncology for ADT management were initiated.
All right. The patient's MRI 3T was performed with an anatomy series axial T2. You can see that there is no evidence of recurrent disease in the prostatectomy bed here, and then we can move on to the dynamic post-contrast series performed with high temporal resolution looking for early enhancement in the bed here and see if there's recurrent disease, which there wasn't. The exam was correctly interpreted without recurrence.
The PSMA PET/CT with the brand name Pylarify was performed about a month later. Here's the rotating MIP of the image. Here's the CT image. CT image fused with the PET/CT data. There's a streak artifact in the CT portion of the study, but the PET/CT remains diagnostic. There's the image of the prostatectomy bed outlined in green. Again, no evidence of radiotracer avid or recurrent disease in the prostatectomy bed.
Review of the additional portions of the exam does show evidence of metastatic disease in-normal-sized retroperitoneal nodes with intense radiotracer uptake. You can see them on CT, on the fused CT PET image, as well as the static MIP here. Similarly, in the posterior mediastinum, there are normal-sized nodes with intense radiotracer uptake. And finally, a left supraclavicular lymph node, a very small node under five millimeters with intense uptake. You can see here where the right arrow is. This is in contrast to the comma-shaped normal cervical ganglia that are sometimes pitfalls in this region and generally have a low-level paired uptake, in this region and can be distinguished from pathologic lymph nodes.
The patient impact here is very clear. The patient has nodes outside the salvage bed, precluding salvage radiation. The patient was referred to medical oncology, started with dual ADT therapy, and had a good response to the PSA trend at the last check in the patient chart.
It's always good to see the foundational data for the Pylarify approval, one of them being the CONDOR trial, a phase three trial enrolling about 113 men with BCR based on Astro or Phoenix criteria. Patients were not on active treatment at the time of PET/CT and had to have either negative or equivocal results from structural imaging, most commonly with CT/MRI or bone scan. A PSMA PET/CT was performed with central blinded reading, followed by a standard of truth, which was either follow-up imaging, biopsy, or assessment on biochemical grounds to confirm the true positivity of the scan.
There are many outcomes from the trial, but perhaps the easily understood one is the detection rate by PSA level. It's a very robust test where detection rates do go up clearly with PSA values, with greater than 90% positivity above a PSA of five in the setting of PSA recurrence, but even in low PSMA realms under .5, where CT and MR, we know from historical data, have very low positive rates. It's about 30 to 40%, which is really good and a substantial improvement over structural imaging.
Overall, 80% of all patients had positive PET/CT results, impacting patient changes in about 73% of those patients. Some examples include a change from salvage radiation to systemic therapy, from systemic to attempted salvage local control, to directed therapy, and then finally, some patients who changed from treatment plans to observation.
In the CONDOR trial, there were no significant side effects. The limitations, of course, are we don't have any long-term data to see what result changes, as directed by PSMA PET/CT, how they impact the change in a patient's prognosis and other outcomes.
In summary, I want to say PSMA PET/CT has the highest detection rate of any modality that we have currently in radiology and nuclear medicine, especially in the setting of biochemical recurrence. It does have impacts on treatment strategies, and patient counseling. It should definitely replace low-value imaging in low PSA values. It is an extremely patient-friendly exam with minimal patient preparation and less radiation than CT and bone scans combined.
I want to thank all the SNMMI prostate cancer outreach working group members for the series and this opportunity.