Subgroup Analysis of Overall Survival among Smoking and Non-Smoking Elderly Patients with HNSCC.

Smoking is a leading cause of head and neck squamous cell carcinoma (HNSCC). However, non-smokers are also affected by HNSCC, and the prognostic factors applicable to older non-smokers with HNSCC are largely unknown. The aim of this study was to determine predictors of overall survival (OS) in patients both with and without a smoking history aged 70 and over at initial diagnosis. Retrospective data of patients aged ≥70 (initial diagnoses 2004-2018) were examined. Evaluated predictors included tumour stage, biological age, health and therapy. A total of 688 patients (520 smokers, 168 non-smokers) were included with a median age of 74. The 5-year OS was 39.6%. Non-smokers had significantly improved OS compared to smokers (52.0% versus 36.0%, p < 0.001). Disease-free survival (DFS) differed significantly between both groups (hazard ratio = 1.3; 95%CI 1.04-1.626). TNM stage and the recommended therapies (curative versus palliative) were comparable. The proportion of p16-positive oropharyngeal carcinomas was significantly higher in non-smokers (76.7% versus 43.8%, p < 0.001). Smokers were significantly more likely to be men ( p < 0.001), drinkers ( p < 0.001), and have poorer health status (Karnofsky performance status, KPS, p = 0.023). They were also more likely to have additional tumours ( p = 0.012) and lower treatment adherence ( p = 0.038). Important predictors of OS identified in both groups, were, among others, alcohol abuse, KPS, Charlson comorbidity index, site of primary tumour, UICC stage and treatment received. Elderly non-smokers are also affected by HNSCC, however, both OS and DFS are increased compared to smokers.