Background: Non-organ cryotherapy represents a unique opportunity to assist systemic therapy by providing new opportunities for local control with low morbidity good healing. We assessed the clinical and imaging outcomes of percutaneous cryotherapy for management of metastatic sites in non-organ soft tissues.

Methods: CT and/or US-guided, percutaneous cryotherapy was performed on 87 metastatic sites in 50 patients with 10 different primaries: renal (N=16, gynecologic (N=11 ),lung (N=7), colon (N=3), sarcoma (N=6), melanoma (N=4), breast (N=1), desmoid (N=1) and esophageal (N=1). Protection of adjacent crucial tissues (e.g. skin, bowel) from cytotoxic temperatures (e.g., <-20C) was achieved by thermocouple monitoring, saline injection and/or direct skin warming. Complications were graded according to Common Toxicity Criteria for Adverse Events Version 3.0 (CTCAE) of the National Cancer Institute. Patients were followed by CT, US, or MRI, at 1, 3, 6, 12, 18, 24, 36 and 48 months. Local recurrence was defined as any asymmetric enhancement of the cryozone and/or focal ablation site enlargement.

Results: Patients generally required minimal sedation and could be discharged within 6 hours. Tumor diameters ranged between 1.0-12 cm, with CT and/or US-visible ice extending ~1cm beyond apparent tumor margins. Tumor ablations involved the retroperitoneum (N=9 ), intraperitoneal region (N=29 ), bone (N=21), and superficial soft tissues (N=28). Grade >3 complications (CTCAE) were seen with only 8 procedures (9% of cases) despite complex and/or larger ablations in difficult locations. Two deaths were unrelated cardiac events within 1 month and 3 patients required surgical intervention for adjacent bowel or ureter damage. At a mean follow-up of 9 months, localized recurrence was noted in 17% (15/86) and sub-categorized as procedure-related 7% (6/86) or disease-related (i.e., growing microscopic satellite foci = 10% = 9/86). Tumor size and location did not appear related to recurrence patterns but larger series are needed.

Conclusions: Percutaneous soft tissue cryotherapy offers a well tolerated treatment alternative, especially for patients with anesthesia risks, painful lesions, or those seeking local control during chemotherapy. Tumor size and/or location do not preclude thorough treatment or pose greater risk with appropriate precautions.