In an Italian single-center phase II trial (RADIOSA) reported in The Lancet Oncology, Marvaso et al found that the addition of androgen-deprivation therapy (ADT) to stereotactic body radiotherapy (SBRT) improved progression-free survival in patients with hormone-sensitive oligorecurrent prostate cancer.
Study Details
In the open-label trial 102 efficacy-evaluable patients from the European Institute of Oncology, IRCCS, Milan, were randomly assigned between August 2019 and April 2023 to receive SBRT plus ADT (n =51) or SBRT alone (n = 51). SBRT consisted of 30 Gy in three fractions every other day (equivalent dose in 2-Gy fractions = 98.6 Gy); ADT consisted of 6 months of treatment with a luteinizing hormone–releasing hormone analog given within 1 week before the start of SBRT. The primary outcome measure was clinical progression-free survival.
Key Findings
Median follow-up of was 31 months (interquartile range = 16–36 months). Median progression-free survival was 32.2 months (95% confidence interval [CI = 22.4 months to not reached) in the SBRT plus ADT group vs 15.1 months (95% CI = 12.4–22.8 months) in the SBRT group (hazard ratio [HR] = 0.43, 95% CI = 0.26–0.72, P = .0010). Rates were 96% vs 63% at 1 year and 61% vs 33% at 2 years.
Median biochemical progression-free survival was 26.8 months (95% CI = 16.8–33.8 months) in the SBRT plus ADT group vs 12.6 months (95% CI = 9.6–13.4 months) in the SBRT group (HR = 0.40, P = .0002). Among all patients, overall survival was 100% at 1 year and 95% at 2 years.
Only one grade 3 treatment-related adverse event was reported, consisting of left ureter stenosis in a patient in the SBRT plus ADT group. No treatment-related grade 4 or 5 events were observed. No late toxicities were observed. ADT-related toxicities (all grade 1 or 2) consisted of hot flushes (43%), asthenia (16%), insomnia (8%), and muscular pain (4%).
The investigators concluded: “To our knowledge, the RADIOSA trial represents the first randomised trial in the metachronous oligometastatic hormone-sensitive prostate cancer setting to report improved clinical progression-free survival with the combination of SBRT and a short course of ADT, although carefully selected patients might still benefit from SBRT alone. By demonstrating improved clinical progression-free survival, the RADIOSA trial reinforces the role of metastasis-directed therapy in delaying systemic treatment escalation. Additionally, it underscores the need for further studies to determine the optimal duration of ADT and identify biomarkers predicting response to SBRT alone.”
Mattia Zaffaroni, MsC, of IEO European Institute of Oncology, IRCCS, Milan, is the corresponding author for The Lancet Oncology article.
Disclosure: The study was funded by the Italian Association of Cancer Research. For full disclosures of the study authors, visit www.thelancet.com.
