This open-label, randomized Phase II trial evaluates whether sequential iodine-125 seed implantation followed by cryoablation improves local tumor control versus single-modality local therapy (125I seeds alone or cryoablation alone) in unresectable solid tumors.
The study is based on a complementary treatment rationale: cryoablation provides rapid cytoreduction of the dominant tumor component, while 125I seed brachytherapy delivers sustained low-dose-rate irradiation that may better suppress residual viable tumor at the periphery and microscopic extension zones. The trial is designed to determine whether this spatial and temporal complementarity translates into superior local disease control without unacceptable toxicity.
Participants will be randomized in parallel to one of three arms: (1) sequential 125I seed implantation followed by cryoablation within a protocol-defined interval, (2) 125I seed implantation alone, or (3) cryoablation alone. Treatment assignment is open label; imaging-based efficacy endpoints will be assessed using a standard blinded assessment process (blinded evaluators), according to protocol-defined criteria.
The primary endpoint is local control rate (LCR) of prespecified target lesions and progression-free survival (PFS). Key secondary endpoints are local progression-free survival (LPFS), overall survival (OS), early pain response, technical success, target-lesion re-intervention rate, and safety (including grade ≥3 treatment-emergent adverse events, CTCAE v5.0). Exploratory analyses include dosimetry-outcome associations, imaging/radiomics biomarkers, and peripheral blood biomarker dynamics.
Adults aged ≥18 years;
Histologically or cytologically confirmed solid tumor that is unresectable and for which local therapy is clinically appropriate;
At least one prespecified target lesion suitable for percutaneous image-guided treatment and considered technically feasible for both 125I seed implantation and cryoablation per investigator assessment (and protocol-defined anatomic/dosimetric safety criteria);
ECOG performance status 0-2;
Prior 125I seed implantation or cryoablation to the same target lesion(s), or other local therapy to the target lesion(s);
Target lesion location or anatomy that, in the investigator's judgment, makes either procedure unsafe or unlikely to achieve protocol-defined coverage/ablation (e.g., inability to meet organ-at-risk constraints or required safety margins);
Uncontrolled bleeding risk or coagulopathy not correctable per protocol; inability to safely hold/bridge anticoagulants/antiplatelets as required.
Clinically significant uncontrolled comorbidities that increase procedural risk;
Li Min
Lead sponsor
Jinan Military General Hospital
Sponsor institution