CT-guided hybrid cryo-thermal co-ablation versus microwave ablation for stage I renal cell carcinoma: a real-world propensity score-matched comparative study

Background: Minimally invasive ablation is an established treatment for stage I renal cell carcinoma (RCC), but comparative evidence is limited. This study presents an exploratory feasibility comparison of co-ablation (Co-A), a hybrid cryo-thermal technique combining liquid-nitrogen freezing with ethanol-mediated heating, with microwave ablation (MWA) in perioperative safety, renal function preservation, and short-term oncologic outcomes.

Methods: Consecutive patients with clinical RCC who underwent computed tomography (CT)-guided percutaneous ablation from January 2017 to December 2024 were retrospectively reviewed. Treatment selection reflected routine clinical judgment. This retrospective study was designed as an exploratory analysis. Propensity score matching (1:2) was performed using age, sex, baseline estimated glomerular filtration rate (eGFR), tumor size, and RENAL nephrometry score (Radius, Exophytic/endophytic properties, Nearness to collecting system, Anterior/posterior, and Location relative to polar lines).

Results: Among 102 screened patients, 78 met eligibility criteria before matching. After matching, 45 patients were included: 15 treated with Co-A and 30 with MWA. All Co-A procedures were completed under local anesthesia, whereas 9 MWA procedures required general anesthesia (P=0.012). Co-A had longer procedure duration (86.2±22.0 vs. 45.4±11.9 min; P<0.001) but shorter hospital stay (2.9±1.4 vs. 4.5±2.6 days; P=0.021). Notably, the shorter hospital stay in the Co-A group should be interpreted with caution, as it may be confounded by the exclusive use of local anesthesia rather than the ablation modality itself. Minor bleeding was more frequent after Co-A (60.0% vs. 23.3%, P=0.039). Short-term eGFR decline was similar between groups (−5.6±11.1 vs. −7.4±11.5 mL/min/1.73 m2; P=0.65). During a median 24-month follow-up, local recurrence occurred in 2 Co-A and 1 MWA patient (13.3% vs. 3.3%; P=0.278).

Conclusions: This exploratory feasibility study suggests that Co-A and MWA demonstrate similar short-term renal functional outcomes in patients with stage I RCC. Co-A was feasible under local anesthesia and associated with shorter hospitalization, but required longer procedure times and was associated with more minor bleeding events. Differences in hospital stay should be interpreted cautiously due to potential anesthesia-related confounding. Oncologic comparisons require cautious interpretation.