Top Line: Molecular imaging is revolutionizing the management of prostate cancer, especially in the recurrent or metastatic setting.
The Study: After prostatectomy, the performance of PET imaging is dependent on PSA level. The rate of detecting disease when the PSA is <0.2 is as low as 40%. At the same time, there is plenty of data showing that salvage radiation is more successful when delivered with a lower PSA. So, we are often left with more than one dilemma. First, can we even get a PET scan approved? Many insurers won’t cover a PET until the PSA exceeds 0.2. And even if it is approved, we know the chances of a positive finding are low with a low PSA. If PET is approved regardless of PSA, do you go ahead and get it with a low PSA or wait so that the chances of seeing gross disease are higher? This large study sought to determine if there is a PSA threshold where the risk of mortality goes up if we wait to start salvage radiation. The study used data from >25,000 men who had radical prostatectomy for localized prostate cancer in Hamburg, Germany or UCSF. Of these, 2.6% received adjuvant radiation, and 12.8% received salvage radiation. The analysis of salvage patients included only those with one high risk factor (Gleason 8+ or pT3-4). Beginning at a PSA cutpoint of 0.25, there was a significant increase in all-cause mortality when salvage RT was delivered at a PSA above vs below the cutpoint. This remained true for all cutpoints up to a PSA of 0.5. Overall, 6.1% received salvage radiation at a PSA ≤0.25, and 6.7% received salvage radiation at a PSA >0.25. Compared to those treated with adjuvant RT, there was no difference in all-cause mortality when salvage RT was delivered at a PSA <0.25. These patients were not staged with PET, so it is still uncertain how best to time a PSMA PET scan with a rising PSA. Considering this study, PSMA PET sensitivity, and the restrictions of some insurers, the sweet spot for waiting to get a PET without increasing the risk of mortality appears to be between 0.2 and 0.25. Easier said than done.
TBL: This study found there is an increase in mortality when salvage RT is delayed beyond a PSA of 0.25 for patients with one high risk factor. | Tilki, J Clin Oncol 2023
The Study: After prostatectomy, the performance of PET imaging is dependent on PSA level. The rate of detecting disease when the PSA is <0.2 is as low as 40%. At the same time, there is plenty of data showing that salvage radiation is more successful when delivered with a lower PSA. So, we are often left with more than one dilemma. First, can we even get a PET scan approved? Many insurers won’t cover a PET until the PSA exceeds 0.2. And even if it is approved, we know the chances of a positive finding are low with a low PSA. If PET is approved regardless of PSA, do you go ahead and get it with a low PSA or wait so that the chances of seeing gross disease are higher? This large study sought to determine if there is a PSA threshold where the risk of mortality goes up if we wait to start salvage radiation. The study used data from >25,000 men who had radical prostatectomy for localized prostate cancer in Hamburg, Germany or UCSF. Of these, 2.6% received adjuvant radiation, and 12.8% received salvage radiation. The analysis of salvage patients included only those with one high risk factor (Gleason 8+ or pT3-4). Beginning at a PSA cutpoint of 0.25, there was a significant increase in all-cause mortality when salvage RT was delivered at a PSA above vs below the cutpoint. This remained true for all cutpoints up to a PSA of 0.5. Overall, 6.1% received salvage radiation at a PSA ≤0.25, and 6.7% received salvage radiation at a PSA >0.25. Compared to those treated with adjuvant RT, there was no difference in all-cause mortality when salvage RT was delivered at a PSA <0.25. These patients were not staged with PET, so it is still uncertain how best to time a PSMA PET scan with a rising PSA. Considering this study, PSMA PET sensitivity, and the restrictions of some insurers, the sweet spot for waiting to get a PET without increasing the risk of mortality appears to be between 0.2 and 0.25. Easier said than done.
TBL: This study found there is an increase in mortality when salvage RT is delayed beyond a PSA of 0.25 for patients with one high risk factor. | Tilki, J Clin Oncol 2023