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Prostate-specific antigen kinetics and biochemical control following stereotactic body radiation therapy, high dose rate brachytherapy, and low dose rate brachytherapy: A multi-institutional analysis of 3,502 patients. Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology Levin-Epstein, R., Cook, R. R., Wong, J. K., Stock, R. G., Jeffrey Demanes, D., Collins, S. P., Aghdam, N., Suy, S., Mantz, C., Katz, A. J., Nickols, N. G., Miszczyk, L., Napieralska, A., Namysl-Kaletka, A., Prionas, N. D., Bagshaw, H., Buyyounouski, M. K., Cao, M., Mahal, B. A., Shabsovich, D., Dang, A., Yuan, Y., Rettig, M. B., Chang, A. J., Jackson, W. C., Spratt, D. E., Lehrer, E., Zaorsky, N. G., Kupelian, P. A., Steinberg, M. L., Horwitz, E. M., Jiang, N. Y., Kishan, A. U. 2020

Abstract

BACKGROUND AND PURPOSE: Stereotactic body radiation therapy (SBRT), low dose rate brachytherapy (LDR-BT) and high dose rate brachytherapy (HDR-BT) are ablative-intent radiotherapy options for prostate cancer (PCa). These vary considerably in dose delivery, which may impact post-treatment prostate-specific antigen (PSA) patterns and biochemical control. We compared PSA kinetics between SBRT, HDR-BT, and LDR-BT, and assessed their relationships to biochemical recurrence-free survival (BCRFS).METHODS AND MATERIALS: Retrospective PSA data were analyzed for 3,502 men with low-risk (n=2223; 63.5%), favorable intermediate-risk (n=869; 24.8%), and unfavorable intermediate-risk (n=410; 11.7%) PCa treated with SBRT (n=1716; 49.0%), HDR-BT (n=512; 14.6%), or LDR-BT (n=1274; 36.4%) without upfront androgen deprivation therapy at 10 institutions from 1990-2017. We compared nadir PSA (nPSA), time to nPSA, achievement of nPSA <0.2 ng/mL and <0.5 ng/mL, rates of nPSA <0.4 ng/mL at 4 years, and BCRFS.RESULTS: Median follow-up was 72 months. Median nPSA and nPSA <0.2 ng/mL were stratified by risk group (interaction p=0.001). Median nPSA and time to nPSA were 0.2 ng/mL at 44 months after SBRT, 0.1-0.2 ng/mL at 37 months after HDR-BT, and 0.01-0.2 ng/mL at 51 months after LDR-BT (mean log nPSA p=0.009 for LDR-BT vs. SBRT or HDR-BT for low/favorable intermediate-risk). There were no differences in nPSA <0.4 ng/mL at 4 years (p=0.51). BCRFS was similar for all three modalities (p=0.27). Continued PSA decay beyond 4 years was predictive of durable biochemical control.CONCLUSION: LDR-BT led to lower nPSAs with longer continued decay compared to SBRT and HDR-BT, but no differences in BCRFS.

View details for DOI 10.1016/j.radonc.2020.07.014

View details for PubMedID 32663537