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SIR 2025

Pain Management/MSK

Traditional Poster

Session: Traditional Poster Presentations

92 - Palliative Microwave Ablation for Painful Osseous Metastases

Monday, March 31, 2025
12:10 PM – 1:10 PM CT
Location: Music City Center, Expo Poster Area
Purpose: To evaluate if palliative microwave ablation (MWA) of painful osseous metastases is safe and effective at improving quality of life.

Materials and Methods: Single-center IRB-approved observational study of 47 patients with mean age of 62.6 ± 11 years (60.4% male) who underwent MWA (Neuwave, Madison, Wisconsin, USA) between 02/2014 and 07/2023 with follow-up until 09/2024. Past medical and oncologic history, pre- and post-procedure pain control, peri-procedural details, and imaging follow-up were collected. Complications were graded according to Common Terminology Criteria for Adverse Events (CTCAE) version 5. Chi-squared, Student's t-tests, and ANOVA were utilized for analysis.

Results: A total of 67 MWA procedures were performed. Most common primary malignancies were renal (27.1%) and lung (20.8%). Most common sites of osseous metastatic disease were the pelvis (70.1%) followed by the thoracolumbar spine (22.4%); 23 (34.3%) sites were previously treated with radiation. Most procedures were performed on an outpatient basis (71.6%). Tumor size was similar (p>0.05) across sites, with a mean largest dimension of 3.4 ± 1.9 cm. Ablation time was consistent across sites (6.7 ± 5.4 min); however, maximum power was higher in pelvic compared to spinal lesions (57.1 ± 14.6 W vs 40.9 ± 9.6 W, p = 0.004).  Concurrent osteoplasty was performed in 94% of cases. Complete coverage of the tumor by the ablation zone occurred in 37.3% of procedures. Pain scores significantly reduced from 7.4 ± 2.6 pre-ablation to 5.3 ± 2.5 post-ablation (p < 0.01). At 2-4 week post-procedure follow-up, 74.6% of patients reported decreased pain. Median follow-up was 6.8 months. Local disease control occurred in 64.7% of patients with an overall survival of 21.3%. No CTCAE grade 3 or higher complications occurred. Two (3.0%) grade 1 intra-procedural complications were noted, cement extravasation and hematoma, neither requiring reintervention. Three (4.5%) patients developed grade 2 transient paresthesias without long-term neurologic sequelae. One (1.5%) patient required surgical decompression for canal stenosis from malignant compression unrelated to procedure. Six (9.0%) additional peri-procedure adverse events not directly related to the procedure were either grade 1-2 in severity.

Conclusion: Palliative MWA for osseous metastases resulted in significant improvement quality of life improvement manifest as pain reduction within the first 2-4 weeks and was found to be safe with low rates of minor (grade 1-2) procedure-related complications.