In a study reported in the Journal of Clinical Oncology, Kwak et al found that prostate-specific antigen (PSA) levels ≥ 0.1 ng/mL within 6 months after completion of radiotherapy were prognostic for poorer outcomes in patients with localized prostate cancer who did or did not also receive androgen-deprivation therapy (ADT).
Study Details
The study included individual patient data from 16 randomized trials evaluating radiotherapy with or without short-tern (3–6 months) or long-term (24–36 months) ADT between 1987 and 2011. The primary outcome measures for the current analysis were metastasis-free survival, prostate cancer–specific mortality, and overall survival from 12 months after random assignment according to PSA level ≥ or < 0.1 ng/mL within 6 months after completion of radiotherapy.
Key Findings
A total of 2,339 (98%) of 2,376 patients allocated to radiotherapy alone; 4,756 (84%) of 5,658 allocated to radiotherapy plus short-term ADT; and 1,258 (77%) of 1,626 allocated to radiotherapy plus long-term ADT had PSA levels of ≥ 0.1 ng/mL within 6 months after completing radiotherapy.
PSA ≥ 0.1 ng/mL within 6 months after completing radiotherapy was associated with poorer outcomes vs PSA < 0.1 ng/mL. Among patients allocated to radiotherapy alone, hazard ratios were 2.24 (95% confidence interval [CI] = 1.21–4.16) for metastasis-free survival, 1.82 (95% CI = 0.51–6.49) for prostate cancer–specific mortality, and 1.72 (95% CI = 0.97–3.05) for overall survival. Among patients allocated to radiotherapy plus short-term ADT, respective hazard ratios were 1.27 (95% CI = 1.12–1.44), 2.10 (95% CI = 1.52–2.92), and 1.26 (95% CI = 1.11–1.44). Among those allocated to radiotherapy plus long-term ADT, respective hazard ratios were 1.58 (95% CI = 1.27–1.96), 1.97 (95% CI = 1.11–3.49), and 1.59 (95% CI = 1.27–1.99).
For patients with PSA < 0.1 ng/mL vs ≥ 0.1 ng/mL, 5-year metastasis-free survival rates were 91% vs 79% for those in the radiotherapy group, 83% vs 76% for those in the radiotherapy plus short-term ADT group, and 87% vs 74% for those in the radiotherapy plus long-term ADT group. Respective rates for 10-year cancer-specific mortality were 10% vs 12%, 6% vs 13%, and 12% vs 7%; respective rates for 10-year overall survival were 52% vs 58%, 62% vs 56%, and 63% vs 50%.
The investigators concluded, “PSA ≥ 0.1 ng/mL within 6 months after radiotherapy completion was prognostic for long-term outcomes in patients treated with [radiotherapy with or without ADT] for localized prostate cancer. This can be used to counsel patients treated with [radiotherapy with or without ADT] and in guiding clinical trial design evaluating novel systemic therapies with radiotherapy plus ADT as well as (de)intensification strategies.”
Christopher J. Sweeney, MBBS, of the South Australian Immunogenomics Cancer Institute, University of Adelaide, Australia, is the corresponding author for the Journal of Clinical Oncology article.
Disclosure: The study was supported by the Prostate Cancer Foundation Challenge Award, as well as grants from Astellas Pharma, Pfizer, Janssen Pharmaceuticals, Millennium Pharmaceuticals, Sotio, Bayer, Dendreon, and Sanofi. For full disclosures of the study authors, visit ascopubs.org.
