Outcome Following Radiation Therapy for Locally Advanced Cutaneous Head and Neck Squamous Cell Carcinoma and Analysis of Factors Associated with Recurrence

Abstract

Radiation therapy is a common treatment modality for skin cancer, either as the primary therapy or as adjuvant treatment in patients with high risk features. However, limited data exist for management of locally advanced head and neck cutaneous squamous cell carcinoma. We report outcome of this unique subset of patients treated with radiation therapy and evaluate prognostic risk factors for recurrences. We retrospectively reviewed the chart of patients with locally advanced cutaneous squamous cell carcinoma who received radiation therapy in our department between January 2001 and December 2017. Patients included in the analysis must have either T3-T4 according to AJCC 8th staging manual or have node positive disease. We excluded patients who had metastatic disease, had tumor outside the head and neck region, or received palliative therapy. We recorded patient (age, sex, immunosuppression status), tumor (primary site, LVI, PNI, T stage, N stage), and treatment (prior surgery, modality, prescription dose, nodal irradiation, concurrent chemotherapy) characteristics. Tumor control and survival rates were calculated using Kaplan-Meier methods and compared using log rank test. We identified 102 patients who met the inclusion criteria. Of the entire cohort, 91 were males and 11 were female. Median age at treatment was 69 (range: 32-94) years old and mean follow up length was 26.8 months. Seventeen patients received concurrent chemotherapy. At the time of analysis, 22 patients had recurred. Five year estimates of local control, regional control, distant control, disease free survival, and overall survival for the entire cohort were 78%, 86%, 91%, 68%, and 57% respectively. The most common pattern of recurrence was local (16 patients), followed by regional nodal recurrences (8 patients), and only 4 patients failed distally. Among those with nodal recurrence, there were slightly more out-of- field (5 patients) than in-field (3 patients) failures. We did not observe any statistical significant differences in term of recurrence and survival rates in regard to T stage, nodal status, elective nodal irradiation for N0 patients, primary tumor site, immunosuppression status, PNI status, or treatment modality (electron versus photon). Patients who had LVI were more likely to experience regional nodal failure at 5 years (36% vs. 12%, p=0.045). In patients with locally advanced head and neck cutaneous squamous cell carcinoma, radiation therapy in conjunction with surgery offers reasonable rates of loco-regional control. We observed a statistical significant higher risk of regional recurrence in patients with LVI. Other risk factors included in our analysis were not shown to correlate with tumor control or survival rates. Ongoing studies seek to identify potential risk factors and patterns of failure following radiation therapy to guide treatment planning.