SEED-CRYO: Sequential 125I Seed Implantation Followed by Cryoablation vs Single-Modality Local Therapy in Unresectable Solid Tumors

Inclusion Criteria:

* 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;
* Adequate organ function, acceptable coagulation status, and the ability to safely undergo percutaneous image-guided procedures;
* Written informed consent provided.

Exclusion Criteria:

* 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.

Active, uncontrolled infection, including uncontrolled local infection at the intended procedure site;

* Clinically significant uncontrolled comorbidities that increase procedural risk;
* Severe organ dysfunction that precludes procedures or follow-up, per protocol-defined thresholds.;
* Pregnancy or breastfeeding;
* Known hypersensitivity to materials/medications essential for the procedures (e.g., contrast agents or anesthetics) that cannot be adequately managed;
* Any condition that would impair reliable outcome assessment or adherence (e.g., inability to undergo required imaging, expected poor compliance), per investigator judgment.