(P 467) TREATMENT OUTCOMES IN AGGRESSIVE ANGIOMYXOMA: A SINGLE INSTITUTION EXPERIENCE

Objective: Aggressive angiomyxoma is a rare mesenchymal tumor arising predominantly in the pelvis and perineum, characterized by a high risk of local recurrence after surgery. Data on its natural history, treatment outcomes with systemic therapy, and genomic characteristics remain limited. In this retrospective study, we evaluated clinical outcomes following surgery and systemic treatments for patients with aggressive angiomyxoma.

Methods: We retrospectively reviewed records of patients with a histologic diagnosis of aggressive angiomyxoma treated at Memorial Sloan Kettering Cancer Center between January 1, 2000, and August 31, 2024. Patients with only a single visit were excluded. The data cutoff was March 18, 2025. Demographics, treatment history, and genomic profile were collected. Overall survival (OS), progression-free survival, and duration of treatment (DOT) were estimated using Kaplan-Meier methodology.

Results: A total of 40 patients were included. The median age at diagnosis was 42 years (range, 12–67), and 35 (87.5%) were female. At a median follow-up of 67 months (range, 6–220), OS data remained immature, with only 2 deaths (5%). The estimated 6-year OS rate was 95.8% (95% CI: 74–100%). Primary surgical resection was performed in 31 patients; 8 required a second surgery, and 1 underwent a third. Among the 9 patients who did not undergo surgery, 7 received systemic endocrine therapy and 2 were managed with surveillance, for durations of 6 and 66 months, respectively. Thirteen patients received first-line endocrine therapy: 8 with GnRH agonists, 2 with aromatase inhibitors, and 3 with combination therapy. Of these, 7 were treated for recurrent disease following prior surgery. The median DOT was 15 months (95% CI: 3 months – not reached). One patient received neoadjuvant endocrine therapy for 2 months prior to surgery. Radiation therapy was rarely used, administered in only 2 patients with recurrent disease. Molecular profiling was performed in a subset: 4 patients underwent next-generation sequencing with MSK-IMPACT, which revealed no pathogenic alterations. Archer fusion testing was performed in 3 patients, with one identifying an HMGA2::LOC105369898 fusion. Additional data on systemic therapy and surgical outcomes will be presented.

Conclusion: Surgical resection remains the cornerstone of treatment in aggressive angiomyxoma, though local recurrence is observed in a subset. Hormonal therapy represents an active and durable option for selected patients.