A national cancer database analysis on stereotactic body radiation therapy of head and neck cancers

Background: To evaluate demographic, clinicopathological, treatment factors including biological effective radiation dose (BED) that influence overall survival in head and neck cancer (HNC) patients treated with stereotactic body radiation therapy (SBRT).

Methods: Between 2004 and 2015, 591 SBRT-treated HNC patients were identified from the National Cancer Data Base. A BED using an alpha/beta ratio of 10 (BED₁₀), was used to compare dose fractionation of different SBRT regimens. Overall survival was estimated using the Kaplan Meier method, and log-rank tests were used to determine statistical significance. Cox regression modeling was used to compute crude and adjusted hazard ratios (HR) with 95% confidence intervals (CI).

Results: Median follow-up was 11.9 (interquartile range, 5.5 to 26.7) months. The 5-year overall survival rate was 15.5%. On multivariate analysis, older age, Charlson-Deyo comorbidity score ≥ 1, history of cancer, tumor, nodal and metastatic stage, and receiving treatment at academic/research program were associated with poor survival. Compared to SBRT alone, superior survival was observed with SBRT with chemotherapy, surgery with SBRT, but not surgery with SBRT and chemotherapy. Improved survival was observed with aa BED₁₀ of ≥59.5 Gy (adjusted HR 0.57, 95% CI 0.46-0.70, P < 0.0001).

Conclusions: Factors affecting associated with worse survival in HNC patients treated with SBRT included older age, patient comorbidities, advanced tumor stage, cancer history, and lower biological effective SBRT dose.

Level of evidence: 2b (individual cohort study).