(P 312) MANAGEMENT OF ADULT HEAD AND NECK SOFT TISSUE SARCOMA: THE MAYO CLINIC EXPERIENCE

Objective: Soft tissue sarcomas (STS) of the head and neck (H&N) are extremely rare, accounting for less than 1% of all STS. Given their rarity and heterogeneity, H&N STS are challenging entities to treat, requiring multidisciplinary collaboration. Herein, we report our institutional experience in the management of H&N STS.

Methods: An Institutional Review Board approved retrospective review of 97 adult patients with H&N STS treated with curative intent radiation therapy (RT) as part of management at Mayo Clinic (Minnesota, Arizona, and Florida) from 1998-2023 was performed. Inclusion criteria were age ≥ 18 years at diagnosis and disease localized to the H&N. Patient, tumor, treatment, toxicity, and outcomes data were gathered. Acute (during or up to 3 months from RT completion) and late (greater than 3 months after RT completion) toxicities were evaluated using the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Kaplan Meier analysis was used to estimate local control (LC), progression-free survival (PFS), and overall survival (OS). Univariate and multivariate Cox regression analyses of disease and treatment characteristics were performed to identify predictors of LC, PFS, and OS. P-values less than 0.05 were statistically significant. All analyses were performed using R software.

Results: Table 1 lists patient, tumor, and treatment characteristics. Most common histologies included 23 (23.7%) angiosarcomas and 13 (13.4%) fibrosarcomas. Twenty-two patients had cutaneous angiosarcomas. Fifteen patients had RT-associated sarcomas. Thirty-seven (38.1%) patients received chemotherapy. Seventy-eight (80.4%) patients underwent surgery; 82% achieved R0 margins. Local recurrence rates by surgery versus no surgery were 15/78 (19.2%) and 9/19 (47.4%), respectively. Local recurrence rates by margin status were 9/62 (14.5%) R0, 4/8 (50%) R1, and 1/6 (16.7%) R2. Twenty-six (26.8%) patients received preoperative RT, 19 (19.6%) received definitive RT, and 52 (53.6%) received postoperative RT. Median total dose was 50 Gy in 25 fractions preoperatively, 60 Gy (IQR 50.4–66) in 33 fractions (IQR 28–35) definitively, and 60 Gy (IQR 59.9–64.8) in 30 fractions (IQR 30–33) postoperatively. Four patients received intraoperative RT. Acute and late grade 3+ toxicity rates were 20.6% and 19.6%, respectively. Most common acute and late grade 3+ toxicities were radiation dermatitis and mucositis, and skin ulceration and dysphagia, respectively. For patients with RT-associated sarcomas, acute and late grade 3+ toxicity rates were 0% and 26.7%, respectively. Median follow-up was 3.2 years (IQR 1.5–6.1). For the entire cohort, 3-year LC, PFS, and OS were 75.1% (66.2–85.1%), 54.2% (44.6–65.8), and 69.8% (60.6–80.3%), respectively (Figure 1). Three-year LC, PFS, and OS for the cutaneous angiosarcoma group were 53.7% (34.6–83.3%), 26% (12.6–53.6%), and 67.9% (50.8%–90.7%), respectively (Figure 2). Table 2 lists univariate analysis results. On multivariate analysis, tumor size [HR 1.18, 95% CI (1.04–1.34), p = 0.009] was an indicator for worse LC. Surgery was an indicator for better LC (p = 0.036) and OS (p = 0.017). Age at RT start [HR 1.04 (1.02–1.06), p < 0.001], N1 stage [HR 3.77 (1.55–9.13), p = 0.003], and tumor size [HR 1.19 (1.08–1.32), p < 0.001] were indicators for worse OS.

Conclusion: In one of the largest known studies of H&N sarcomas treated with RT, we report 3-year LC, PFS, and OS of 75.1%, 54.2%, and 69.8%, respectively. Larger tumor size was an indicator for worse LC. Surgery correlated with improved LC and OS. Older age, N1 stage, and larger tumor size were indicators for worse OS. Multidisciplinary treatment is imperative for this disease entity and local treatment intensification may be warranted for those at higher risk of local failure.