3615 - Definitive and Salvage Stereotactic Body Radiation Therapy (SBRT) for Nonmelanoma Skin Cancer of the Head and Neck

L. C. Callier¹, K. Brito², N. M. Woody³, J. Miller⁴, J. L. Geiger⁵, T. Sussman⁶, E. Yilmaz⁷, A. Vidimos⁸, C. M. Poblete-Lopez⁸, A. Vij⁸, M. McEnery-Stonelake⁹, S. A. Koyfman³, and S. R. Campbell⁴; ¹Ohio University Heritage College of Osteopathic Medicine, Athens, OH, ²Cleveland Clinic Foundation, Cleveland, OH, ³Department of Radiation Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH, ⁴Cleveland Clinic, Cleveland, OH, ⁵Department of Hematology and Medical Oncology, Taussig Cancer Center, Cleveland Clinic, Cleveland, OH, ⁶Department of Hematology/Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH, ⁷Department of Medical Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH, ⁸Department of Dermatology, Cleveland Clinic Foundation, Cleveland, OH, ⁹Department of Dermatology, Cleveland Clinic, Cleveland, OH

Purpose/Objective(s): Patients with head and neck locoregional only nonmelanoma skin cancer (NMSC) who are not candidates for surgery or immunotherapy, or progress after prior treatment, have limited options. SBRT offers a noninvasive, short, definitive treatment with the potential for durable control. Materials/

Methods: An IRB approved registry of head and neck cancer patients was queried for NMSC treated with 5 fraction SBRT (minimum 35 Gy) from 2014 to present. Acute toxicity (<90 days from SBRT) graded per CTCAE v4.0 was evaluated. Crude rates of locoregional control (LRC) and distant metastasis (DM) were calculated.
Results: Head and neck SBRT was used in 13 patients with NMSC. The median follow up was 9.8 months (range 3.8-57.6) and median age was 73.4 years (range 60.7-91.5). Histologies included squamous cell carcinoma (77%), basal cell carcinoma (15%), porocarcinoma (8%). 15% were immunosuppressed, 31% had prior parotidectomy, and 77% had prior overlapping radiation. Median time from prior radiation to SBRT was 12 months (range 4.1-17.4). Treatment site was neck/parotid in 77%, base of skull 23%. Concurrent and adjuvant cetuximab and immunotherapy was given in 23% and 15%, respectively. SBRT dose was 45 Gy (7.5%), 40 Gy (69%), 37.5 Gy (7.5%), 35 Gy (15%). Secondary elective volume of 25-35 Gy was used in 38.5%. Median high dose and elective PTV volumes were 79 cc (range 7-165) and 276 cc (range 158-631), respectively. Bolus was used in 38.5%. LRC was 100% for patients without prior RT (N=3) and 60% for re-irradiation (N=6/10), with all failures within the high dose region. DM developed in 38.5% (N=5), 2 with synchronous locoregional failure. Acute grade 3+ toxicity was seen in 15% of patients (N=2), which included grade 3 dermatitis (N=1) and grade 3 meningitis (N=1; exposed calvarium present at baseline).
Conclusion: SBRT in the primary or re-irradiation setting offers a short and effective treatment option for patients with NMSC that are not candidates for, or refuse, standard therapy. Longer follow up is needed to assess the incidence of late effects, however this is a promising treatment approach for select patients.