The Impact of Smoking Cessation and Continuation on Recurrence and Survival in Patients with Head and Neck Cancer: A Systematic Review of the Literature.

BACKGROUND The impact of smoking continuation or cessation on the outcome of head and neck cancer (HNC) patients concerning recurrence and survival rates is not well understood. We aimed to analyze the prognostic role of smoking habits in patients with newly diagnosed HNC and the effects on survival, recurrence rates, and second primary tumor (SPT) development. METHODS A systematic literature review of the databases PubMed and Web of Science was performed in October 2019 using the search words "head and neck cancer" and "smoking cessation." Articles analyzing the effects of ongoing smoking or smoking cessation in HNC patients were included. RESULTS Twelve studies published from 1993 to 2016 including 6,308 patients with HNC of stages I-IV were eligible for analysis. The median follow-up was 5 years. Six of 8 studies revealed an improved outcome concerning the median overall survival or survival rates favoring smoking cessation. Regarding recurrence rates, 5 of 6 studies indicated a statistically significant benefit associated with smoking cessation, and 2 of 3 studies showed a lower risk for SPT associated with postdiagnosis smoking cessation. CONCLUSION Smoking cessation in patients with newly diagnosed HNC is associated with improved outcomes concerning overall survival, recurrence rates, and SPTs. Further research is needed to validate these results and to evaluate the specific effects on different tumor types and treatment approaches.