Prolongation of definitive head and neck cancer radiotherapy: Survival impact and predisposing factors

• Published in: Radiotherapy and oncology 2021-03, Vol.156, p.201-208
• Main Authors: Xiang, Michael, Gensheimer, Michael F., Pollom, Erqi L., Holsinger, Floyd Christopher, Colevas, Alexander D., Le, Quynh-Thu, Beadle, Beth M.
• Format: Article
• Language: English
• Subjects: Adult; Carcinoma, Squamous Cell; Causality; Cohort Studies; Combined modality therapies; Head and neck cancer; Head and Neck Neoplasms - radiotherapy; High-volume hospitals; Humans; Propensity Score; Radiation oncology; Squamous cell carcinoma
• ISSN: 0167-8140; 1879-0887
• DOI: 10.1016/j.radonc.2020.12.025

•Prolongation of the radiation course increased the hazard of death by 2% per day.•Prolongation >8 days was especially deleterious, while 1–3 days was not adverse.•Use of systemic therapy increased the risk of prolongation by 2-fold.•High facility volume (top quartile) decreased the risk of prolongation by 2-fold.•Other predictors included race, insurance status, comorbidity, and stage. To quantify the survival impact of prolongation of definitive radiotherapy (RT) for head and neck cancer in a national, modern cohort, and to identify predictive factors for prolongation. The National Cancer Database was queried for adults with non-metastatic cancer of the nasopharynx, oropharynx, larynx, or hypopharynx diagnosed 2004–2015, treated with definitive RT to 66–70 Gy in 30–35 fractions at 2–2.2 Gy per fraction. Multivariable Cox regression and propensity score matching were used to model the survival impact of RT prolongation, adjusting for potential confounders such as age and comorbidity. Predictors of RT prolongation were identified using multivariable multinomial logistic regression. In total, 36,367 patients were identified. As a continuous variable, RT prolongation increased the relative hazard of death by 2% per day (P 8 days) had lower absolute 4-year overall survival by 4% and 12%, respectively (P 11.5 patients/year). RT prolongation, especially >8 days, is significantly deleterious. Systemic therapy and facility volume were major predictors. Early identification of patients at increased risk of treatment interruptions may facilitate implementation of preventive measures.