Incidence and Management Trends in Advanced Head and Neck Non-Melanoma Skin Cancer in Ontario.

Head and neck non-melanoma skin cancers (H&N NMSCs) account for most head and neck malignancies. While primary treatment comprises surgery, adjuvant radiation is recommended in advanced tumors. Radiation oncology practice patterns for resected locally advanced (rLA) and locoregional (rLR) H&N NMSCs have not been well characterized. Using data from the Institute for Clinical Evaluative Sciences (ICES) between 2003 and 2019, we conducted a longitudinal, population-based study characterizing disease incidence, survival outcomes, and radiation utilization patterns. Among 2962 rLA and 1055 rLR cases, rLA incidence rose more than tenfold compared to population growth; however rLR incidence remained stable. Radiation oncology consultations occurred in 29.6% of rLA and 50.7% of rLR patients. Increased age, multiple cancers at diagnosis, non-rural demographic, and higher SES were observed to be correlated to receipt of adjuvant radiation treatment. Only 19.4% of rLA and 37.95 of rLR disease received adjuvant RT, which is much lower than expected based on international guidelines. Five-year overall survival (OS) was 69% (95% confidence interval (CI): 67-71%) for rLA and 68% (95% CI: 65-71%) for rLR disease. These findings highlight the burden of advanced H&N NMSC, low rates of radiation utilization and the need for improving referral pathways and guideline adherence.