This is an archive of papers published by the staff and faculty of Fox Chase Cancer Center. For questions about content, please contact Talbot Research Library
Last updated on
Pirlamarla AK , Hansen CC , Deng M , Handorf E , Paly J , Wong JK , Hallman MA , Chen DYT , Geynisman DM , Kutikov A , Horwitz EM
Early PSA kinetics for low- and intermediate-risk prostate cancer treated with definitive radiation therapy
Pract Radiat Oncol. 2021 Jul 21
PMID: 34303033 URL: https://www.ncbi.nlm.nih.gov/pubmed/34303033
AbstractPURPOSE: This study uses a patient-specific model to characterize and compare ideal PSA kinetics for low- and intermediate-risk prostate cancer following definitive radiation treatment with conventionally fractionated (CFRT), hypofractionated (HFRT), stereotactic body radiation therapy (SbRT), or brachytherapy, both high-dose-rate (HDR) and low-dose-rate (LDR). METHODS AND MATERIALS: This retrospective analysis includes low- and intermediate-risk prostate cancer patients treated between 1998 and 2018 at an NCI-designated Comprehensive Cancer Center. Demographics and treatment characteristics were prospectively collected. Patients had at least two PSA measurements within 24-months of treatment and were free from biochemical recurrence. The incidence of, time to, and risk factors for PSA nadir (nPSA) and bounce (bPSA) were analyzed at 24-months following radiotherapy. Ideal PSA kinetics were characterized for each modality and compared. RESULTS: Of 1,042 patients, 45% had low-risk cancer, 37% favorable intermediate-risk, and 19% unfavorable intermediate-risk. nPSA were higher for ablative modalities, both as absolute nPSA and relative to initial PSA (iPSA). Median time to nPSA ranged from 14.8 to 17.1 months. Over 50% treated with non-ablative therapy (CFRT, HFRT, and LDR) reached an nPSA threshold of ≤0.5 ng/mL compared to 23% of SbRT and 33% of HDR cohorts. The incidence of bPSA was 13.3% and not affected by treatment modality, Gleason Score, or prostate volume. PSA decay rate was faster for ablative therapies in the 6-24 month period. CONCLUSIONS: Analysis of PSA within 24-months following radiation therapy revealed ablative therapies are associated with a latent PSA response and higher nPSA. Multivariable logistics modeling revealed younger age, iPSA above the median, presence of bPSA, and ablative therapy as predictors for not achieving nPSA ≤0.5 ng/mL. PSA decay rate appears to be faster in ablative therapies following a latent period. Understanding the different PSA kinetic profiles is necessary to assess treatment response and survey for disease recurrence.
Notes1879-8519 Pirlamarla, Aneesh K Hansen, Chase C Deng, Mengying Handorf, Elizabeth Paly, Jonathan Wong, J Karen Hallman, Mark A Chen, David Y T Geynisman, Daniel M Kutikov, Alexander Horwitz, Eric M Journal Article United States Pract Radiat Oncol. 2021 Jul 21:S1879-8500(21)00204-6. doi: 10.1016/j.prro.2021.07.003.