In decline.

Are there differences in PSA kinetics across radiation modalities? This retrospective analysis compared 24-month PSA kinetics of >1000 men with low (45%) and intermediate risk (37% favorable, 19% unfavorable) following definitive treatment with conventional fractionation (CF, 38%), moderate hypofractionation (HF, 11%), SBRT (5%), ( 11%) HDR, or LDR (35%), but no ADT. Nadir was around 0.5 for CF, HF, and LDR, but it was higher after SBRT (1.1) and HDR (0.9). In addition, <⅓ of SBRT and HDR patients had nadir below 0.5 and < 10% below 0.2. While this seems counter to another recent study of SBRT kinetics in a larger population, this study focused on early PSA kinetics, which we know may continue to decline beyond 24 months. There were no major differences in the rates or magnitudes of PSA bounce per modality. Ultimately, their data suggests ablative treatment modalities like SBRT or HDR may have a more prolonged PSA response than non-ablative modalities. | Pirlamarla, Pract Radiat Oncol 2021