The Affects of Adjuvant Radiotherapy on Survival in Elderly Patients with Advanced Head & Neck Squamous Cell Carcinoma

Abstract

<h3>Purpose/Objective(s)</h3> For locally advanced head and neck squamous cell carcinoma (HNSCC), adjuvant radiotherapy (RT) following definitive surgical resection has been widely shown to confer a survival benefit. However, the presence of this survival benefit for elderly patients has not been clearly demonstrated. Given the numerous morbidities associated with RT, we sought to investigate the difference in overall survival (OS) associated with adjuvant therapy in elderly patients (80+). <h3>Materials/Methods</h3> The National Cancer Database (NCDB) was queried for all cases of HNSCC between 2004-2016 using ICD-O-3 histology and morphology codes. Those with advanced disease, defined as pathologic T3/T4 and/or N2b or greater, were selected for inclusion. Exclusion criteria included those with HPV-positive disease, distant metastasis, positive surgical margins, and/or death within 30 days of surgery. Patients who received neoadjuvant treatment and/or systemic therapy were additionally excluded. Patients treated with surgical resection alone were compared to those treated with surgery + adjuvant RT. OS was compared between these groups in patients younger than 80 and separately for those 80+ using Kaplan meier analysis. Odds ratios (OR) were assessed using Cox proportional hazards to account for differences in patient characteristics, primary site, and HNSCC stage. <h3>Results</h3> NCDB identified 16,504 cases meeting inclusion criteria with 7,375 (44.7%) treated with surgery alone and 9,129 (55.3%) receiving adjuvant RT. The mean age was 63.8 years (SD = 12.0) with 89.0% of patients aged <80 and 11.0% aged 80+. In the younger cohort, adjuvant RT was associated with a significant increase in OS relative to surgery alone when assessed at 1 year (88.4% vs. 83.8%, p=<0.001), 3 years (64.0% vs. 59.2%, p=<0.001) and 5 years (52.8% vs 47.2%, p=<0.001). In the elderly cohort, there was no significant difference in OS between adjuvant RT and surgery alone when measured at 1 year (73.4% vs. 74.8%, 0.296), 3 years (45.8% vs. 41.8%, p=0.465), or 5 years (28.2% vs. 27.7% p=0.759). Cox regression was utilized to assess the OR for 5-year OS associated with adjuvant RT after accounting for differences in primary site, T-stage, and N-stage. In patients under 80, surgery alone remained a significant predictor of 5-year mortality with an OR of 1.32 (95% CI 1.25-1.39, p=<0.001). In the elderly cohort, there was no significant difference between groups with surgery alone carrying an OR of 1.10 (95% CI 0.96-1.25, p=0.169). <h3>Conclusion</h3> In elderly patients undergoing definitive surgical treatment of locally advanced HSNCC, adjuvant RT may not provide a similar overall survival benefit relative to younger patients. Further research is needed to explore differences in disease-specific survival and quality of life to guide shared decision making in this patient population.