E1031. Ablative Techniques to Treat Painful Osseous Metastases: Current Evidence in the Literature
  1. Arun Chockalingam; Mount Auburn Hospital
Bony metastases occur in 60 - 84% of cases in the presence of an underlying primary. There is risk of pathologic fracture, spinal cord compromise, and metabolic effects. The annual healthcare burden for treatment of complications amounts to about $12.6 billion. External beam therapies provide pain relief in majority of patients, but are often complicated by delayed onset and insufficient duration of pain relief, radio-resistance, and increased fracture risk (11 - 39% of patients). As these patients are usually poor surgical candidates, percutaneous ablative therapies are playing an increasing role in treatment.

Educational Goals / Teaching Points
To discuss current evidence of ablative techniques in the treatment of painful osseous metastases.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Radiofrequency-ablation (RFA) involves high-frequency alterative current inducing rapid heat generation producing temperatures greater than 60degC. A recent meta-analysis describes 44% pain reduction within 1 week and 67% pain reduction after 24 weeks. The OsteoCool RF ablation system uses a bipolar ablation probe that automatically adjusts the power to maintain RFA within a certain treatment range. A recent study reported 57% reduction of pain score using OsteoCool at 6 months. Cryoablation uses pressurized room temperature gases to rapidly cool soft tissues, reaching temperatures less than -100degC. The recent MOTION trial showed average change in score postprocedure of -2.6/10 at 8 weeks. Compared with RFA, cryoablation was shown to reduce analgesic use and total length-of-stay. Microwave ablation involves oscillation of water molecules causing tissue necrosis, with theoretically faster heating of larger tissue volumes with reduced heat sink compared to RFA. Current evidence for microwave ablation is limited but there few studies showing feasibility and efficacy.

Further investigation evaluating efficacy of different types of ablation compared to radiation and endoscopic surgery across different tumor types would guide clinicians in selecting optimal treatment plan.