Top Line: What do prostate-specific PET scans show us, really?
The Study: While many studies have investigated the individual sensitivities of fluciclovine and PSMA PET scans, and some have even compared sensitivities between the two, none have really delved into the types of cancer detected by either scan. Wait, aren’t they both detecting prostate cancers? Yes, but these authors recognised that the two imaging modalities appear to detect different prostate tumor locations. Stay with us. This fascinating study looks at variations in genetic signatures, and even associated survival outcomes, among tumors that light up with one versus the other radiotracer. The authors accessed whole-transcriptome profiles of nearly 18K prostatectomy specimens sent for commercial testing with Decipher. They discovered higher PSMA expression is directly correlated with a higher Decipher risk score. As such, it is also significantly associated with a Gleason score 8+ and / or nodal disease. Conversely, surrogate expression of fluciclovine (via its transporters LAT3, and ASCT2) is significantly associated with the opposite. They then turned to a retrospective cohort of 780 men on whom they had both genomic and clinical outcomes data. As hypothesized from what we just said, both the 10% (n=78) of men with the highest PSMA expression and the 10% of men with the lowest LAT3 and ASCT2 expression had significantly shorter metastasis-free survival. While this is all pretty cool—no, hot—this is purely hypothesis-generating as it doesn’t show correlation between any of this and actual imaging findings.
TBL: Genomic prostate cancer signatures point to PSMA-hot tumors being higher risk for metastatic dissemination than fluciclovine-hot tumors. | Chu, Euro Urol 2021