In a phase II trial (PEACE V–STORM) reported in The Lancet Oncology, Ost et al found that elective nodal radiotherapy (ENRT) to the pelvis was associated with longer metastasis-free survival vs metastasis-directed therapy (MDT) in patients with pelvic nodal oligorecurrences of prostate cancer.
Study Details
In the open-label trial, 190 evaluable patients with PET-detected pelvic nodal oligorecurrence (up to five nodes) following radical local treatment were enrolled from sites in Australia, Belgium, Italy, Norway, Spain, and Switzerland between June 2018 and April 2021. Patients were randomly assigned to receive ENRT (n = 93) or MDT (n = 97). Patients in the ENRT group received a 45 Gy dose in 25 fractions to the pelvis, with a simultaneous integrated boost of 65 Gy to the PET-positive nodes or salvage lymph node dissection, with 6 months of androgen-deprivation therapy. Patients in the MDT group received salvage nodal dissection or stereotactic body radiotherapy (30 Gy in three fractions every other day), with 6 months of androgen-deprivation therapy. The primary endpoint was metastasis-free survival. A value of P ≤ .20 was considered significant for the primary endpoint. A value of P ≤ .05 was considered significant for the other oncologic outcomes.
Key Findings
Median follow-up was 50 months (interquartile range = 42–58 months). The 4-year metastasis-free survival was 76% (80% confidence interval [CI] = 69%–81%) in the ENRT group vs 63% (80% CI = 56%–69%) in the MDT group (hazard ratio [HR] = 0.62, 80% CI = 0.44–0.86, P = .063).
At 4 years, biochemical relapse–free survival was 57% (80% CI = 50%–64%) in the ENRT group vs 41% (80% CI = 34%–47%) in the MDT group (HR = 0.62, 80% CI = 0.48–0.80, P = .014); locoregional relapse-free survival was 85% (80% CI = 80%–90%) in the ENRT group vs 62% (80% CI = 55%–69%) in the MDT group (HR = 0.45, 80% CI = 0.31–0.65, P = .0047); and androgen-deprivation therapy–free survival was 77% (80% CI = 70%–82%) in the ENRT group vs 60% (80% CI = 53%–67%) in the MDT group (HR= 0.60, 80% CI = 0.43–0.83, P = .049).
At 4 years, grade ≥ 2 genitourinary adverse events occurred in 31% of the ENRT group vs 28% of the MDT group, and grade ≥ 2 gastrointestinal adverse events occurred in 9% vs 7%. The most common grade 3 adverse events were urinary incontinence (10% vs 6%) and diarrhea (2% vs 1%). No grade 4 events were observed, and no treatment-related deaths were reported.
The investigators concluded: “To our knowledge, this is the first randomised trial for metachronous PET-detected nodal recurrences comparing two local treatment approaches (MDT and ENRT) in combination with 6 months of androgen-deprivation therapy. By showing an improved metastasis-free survival with ENRT, this trial establishes ENRT as a potential standard treatment approach, awaiting a phase III trial confirming these results.”
Piet Ost, MD, of the Department of Radiation Oncology, Iridium Network, Antwerp, Belgium, is the corresponding author of The Lancet Oncology article.
Disclosure: The study was funded by Movember Foundation, Kom Op Tegen Kanker, and Stichting tegen Kanker. For full disclosure of all study authors, visit The Lancet Oncology.
