Risk factors for aspiration pneumonia after definitive chemoradiotherapy or bio-radiotherapy for locally advanced head and neck cancer: a monocentric case control study

Background: Chemoradiotherapy (CRT) and bio-radiotherapy (BRT) are recognized as standard therapies for head and neck cancer (HNC). Aspiration pneumonia after CRT or BRT is a common late adverse event. Our aim in this study was to evaluate the cause-specific incidence of aspiration pneumonia after CRT or BRT and to identify its clinical risk factors. Methods: We performed a retrospective analysis of 305 patients with locally advanced HNC treated by CRT or BRT between August 2006 and April 2015. Results: Of these 305 patients, 65 (21.3%) developed aspiration pneumonia after treatment. The median onset was 161 days after treatment. The two-year cause-specific cumulative incidence by CRT or BRT was 21.0%. Multivariate analysis revealed five independent risk factors for aspiration pneumonia, namely, habitual alcoholic consumption, use of sleeping pills at the end of treatment, poor oral hygiene, hypoalbuminemia before treatment, and the coexistence of other malignancies. A predictive model using these risk factors and treatment efficacy was constructed, dividing patients into low- (0-2 predictive factors), moderate- (3-4 factors), and high-risk groups (5-6 factors), the two-year cumulative incidences of aspiration pneumonia of which were 3.0, 41.6, and 77.3%, respectively. Aspiration pneumonia tended to be associated with increased risk of death, although this was not statistically significant (multivariate adjusted hazard ratio 1.39, P = 0.18). Conclusion: The cause-specific incidence and clinical risk factors for aspiration pneumonia after definitive CRT or BRT were investigated in patients with locally advanced HNC. Our predictive model may be useful for identifying patients at high risk for aspiration pneumonia.