We sought to evaluate the prognostic impact of prostate-specific antigen (PSA) at 6 months after completion of radiotherapy (RT) in patients treated with RT alone, RT plus short-term (st; 3-6 months), and RT plus long-term (lt; 24-36 months) androgen-deprivation therapy (ADT).
Individual patient data were obtained from 16 randomized trials evaluating RT ± ADT for localized prostate cancer (PCa) between 1987 and 2011. The lowest PSA recorded within 6 months after RT completion was identified and categorized as < or ≥0.1 ng/mL. The primary outcomes were metastasis-free survival (MFS), PCa-specific mortality (PCSM), and overall survival (OS), from 12 months after random assignment.
Ninety-eight percent (n = 2,339/2,376) of patients allocated to RT alone, 84% (n = 4,756/5,658) allocated to RT + stADT, and 77% (n = 1,258/1,626) allocated to RT + ltADT had PSA ≥0.1 ng/mL within 6 months after completing RT. PSA ≥0.1 ng/mL was associated with lower MFS and OS and higher PCSM among patients allocated to RT ± ADT (RT - MFS: hazard ratio [HR], 2.24 [95% CI, 1.21 to 4.16]; PCSM: subdistribution hazard ratio [sHR], 1.82 [0.51 to 6.49]; OS: HR, 1.72 [0.97 to 3.05]; RT + stADT - MFS: HR, 1.27 [1.12 to 1.44]; PCSM: sHR, 2.10 [1.52 to 2.92]; OS: HR, 1.26 [1.11 to 1.44]; RT + ltADT - MFS: HR, 1.58 [1.27 to 1.96]; PCSM: sHR, 1.97 [1.11 to 3.49]; OS: HR, 1.59 [1.27 to 1.99]). Five-year MFS rates among patients allocated to RT, RT + stADT, and RT + ltADT were 91% versus 79%, 83% versus 76%, and 87% versus 74%, respectively, based on PSA < or ≥0.1 ng/mL.
PSA ≥0.1 ng/mL within 6 months after RT completion was prognostic for lt outcomes in patients treated with RT ± ADT for localized PCa. This can be used to counsel patients treated with RT ± ADT and in guiding clinical trial design evaluating novel systemic therapies with RT + ADT as well as (de)intensification strategies.
Journal of clinical oncology : official journal of the American Society of Clinical Oncology. 2024 Mar 12 [Epub ahead of print]
Lucia Kwak, Praful Ravi, John G Armstrong, Veronique Beckendorf, Joseph L Chin, Anthony V D'Amico, David P Dearnaley, Savino M Di Stasi, Silke Gillessen, Himanshu Lukka, Nicolas Mottet, Pascal Pommier, Wendy Seiferheld, Matthew R Sydes, Bertrand Tombal, Almudena Zapatero, Meredith M Regan, Wanling Xie, Christopher J Sweeney
Department of Urology, Catholic University, Rome, Italy., Oncology Institute of Southern Switzerland, EOC, Bellinzona, Switzerland., McMaster University and Juravinski Cancer Centre, Hamilton, ON, Canada., Mutualite Francoise Loire, St Etienne, France., Institut de Cancérologie de l'Ouest, Angers, France., NRG Oncology, Philadelphia, PA., Medical Research Council at UCL, London, United Kingdom., Cliniques Universitaires Saint-Luc, Brussels, Belgium., Department of Radiation Oncology, La Princesa University Hospital, Health Research Institute, Madrid, Spain., 6South Australian Immunogenomics Cancer Institute, University of Adelaide, Adelaide, SA, Australia.