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Cryoablation as an effective treatment for desmoid tumors: A single-institution case series.

e23543 Background: Desmoid tumors are locally invasive mesenchymal neoplasms of fibroblastic origin arising in deep soft tissue. Despite a rare incidence of 2.4-4.3 per one million and an inability to metastasize, desmoid tumors can cause significant morbidity by invading surrounding structures, causing pain, anatomic deformities, and, in some cases, death. Due to the high post-excision recurrence rate (21-29%) and frequent spontaneous regression or stabilization (50-88%), active surveillance is the first-line treatment for desmoid tumors. Most therapeutic agents only achieve tumor stability and response rates of 10-30%. As such, a large subset of patients face disease progression without an effective therapeutic option. In this context, percutaneous cryoablation arises as a novel treatment for desmoid tumors. This retrospective chart review case series aims to describe the effectiveness of cryoablation in the treatment of desmoid tumors. Methods: We retrospectively reviewed medical records of patients with a pathologically confirmed desmoid tumor who received computed tomography (CT) guided percutaneous cryoablation at a single academic hospital between 2010 and 2021. We defined objective response rate (ORR) as the percentage of patients who have partial or complete response to cryoablation. Disease progression (PD), Stable Disease (SD), Partial Response (PR), and Complete Response (CR) were defined per mRECIST criteria. Results: We identified nine patients (8 female, mean age 33) with desmoid tumors who underwent percutaneous cryoablation. The most common tumor location was the abdominal wall (n = 5,) and the median longer axis tumor size was 9.5 cm (range: 4.5-16 cm). Seven patients received previous systemic treatments. Sorafenib (n = 6) was the most common systemic therapeutic option, followed by methotrexate/vinblastine, Adriamycin/dacarbazine, tamoxifen, nirogacestat, and sulindac. Before cryoablation, six of the seven patients receiving systematic therapies had PD; one had SD. After cryoablation, seven underwent post-cryoablation imaging. Mean time to initial post-op follow-up was 38.85 days (range: 22-60 days). Six patients achieved PR (66.67%), one patient maintained SD (11.11%), and two (22.22%) were lost to follow-up. Two patients with PR regressed to SD two and three months after initial post-cryoablation imaging, respectively, and one with SD improved to PR after eleven months. As such, ORR was 71.43% (95% CI: 0.352 to 1.08). Conclusions: Our data support cryoablation as an effective therapy for decreasing tumor burden in multi-treatment resistant desmoid tumor patients. Although larger studies are needed to assess efficacy and safety, with an ORR of over 70% and a disease control rate of over 75%, cryoablation demonstrates promising results without the toxicity of systemic therapy and thus may be an effective strategy for multi-treatment resistant desmoid tumors.