What are the inclusion criteria and primary endpoints for the PSMA‑SRT phase III trial (Calais et al)?

1. Trial design and target population: randomized, prospective phase III

PSMA‑SRT is a randomized, prospective phase III trial enrolling 193 patients who were candidates for salvage radiotherapy after radical prostatectomy and who experienced biochemical recurrence; participants were randomized to proceed directly to standard SRT (control arm, n ≈ 90) or to undergo a 68Ga‑PSMA‑11 PET/CT prior to SRT planning (investigational arm, n ≈ 103) ^{[1] [3]}. The study was designed to follow patients for five years and to capture whether molecular imaging changes management and ultimately affects the biochemical success of SRT ^{[3] [4]}.

2. Inclusion criteria — what the public sources explicitly state and what they do not

Public-facing protocol summaries and the BMC Cancer methods section indicate the enrolled population consists of patients with biochemical recurrence following prostatectomy who were being considered for SRT, reflecting the common clinical scenario where SRT is typically started at PSA levels below 1 ng/mL because conventional imaging is insensitive at low PSA ^[1]. The available excerpts do not list the full numeric eligibility thresholds (exact PSA window, performance status, age limits, prior therapies, or specific laboratory cutoffs) in the snippets supplied here, so a complete line‑by‑line inclusion/exclusion list cannot be reconstructed from these sources alone ^[1].

3. Primary endpoint: biochemical progression‑free survival (BPFS) after starting SRT

The trial’s stated primary endpoint is the “success rate of SRT measured as biochemical progression‑free survival (BPFS) after initiation of SRT,” meaning the principal outcome is time to biochemical failure following treatment with salvage radiotherapy, as captured in the protocol and trial registry summaries ^{[2] [1] [3]}. The choice of BPFS reflects the clinical question at the heart of the trial: whether PSMA PET‑directed planning can improve biochemical control compared with standard planning when patients present with low‑volume biochemical recurrence ^[1].

4. How PSMA findings affect analysis: handling of extra‑pelvic metastases

The protocol anticipates that approximately 13% of patients randomized to the PSMA‑PET arm will be found to have PSMA‑positive extra‑pelvic (non‑pelvic) metastatic disease and, as a consequence, may not proceed to local SRT; these patients are excluded from the primary endpoint analysis but are still followed for outcomes and safety (the randomization ratio of 1:1.13 accounts for this expected attrition) ^[2]. This pre‑specified analytic approach means the BPFS endpoint is intentionally measured only among those who actually receive SRT, which must be considered when interpreting the trial’s effectiveness signal versus a pure intention‑to‑treat comparison ^{[2] [3]}.

5. Practical implications, limitations and unresolved details

The trial design leaves critical treatment choices—such as whether to include pelvic lymph nodes in the radiation field or to add androgen‑deprivation therapy—at the discretion of treating radiation oncologists, permitting real‑world variability in delivery of SRT ^[3]. That pragmatic flexibility strengthens external validity but complicates causal attribution of any BPFS differences solely to PSMA‑guided imaging; additionally, publicly available summaries here do not provide the exact BPFS definition used (PSA thresholds, confirmatory testing schedule) or all detailed eligibility criteria, so those seeking the full protocol‑level specifics should consult the BMC Cancer full text and trial registry entries for granular inclusion/exclusion language and endpoint definitions ^{[1] [2]}.