Objective: To identify factors associated with interruption or early discontinuation of treatment in patients receiving radiotherapy for head and neck cancer, because it is believed that such treatment interruption or early discontinuation increases the risk of disease relapse and adversely influences survival. Design, Setting, and Patients: Using the Surveillance, Epidemiology, and End Results (SEER)– Medicare linked database, we identified Medicare beneficiaries 66 years or older who were diagnosed as having local or regional head and neck cancer from January 1, 1997, through December 31, 2003. For each case, we calculated the timing and duration of radiotherapy using Medicare claims data. We then performed logistic regression analyses to estimate the association between tumor and clinical characteristics and early discontinuation of and/or interruptions in radiotherapy. Main Outcome Measure: Completion of uninterrupted radiotherapy. Results: A substantial proportion of patients (39.8% overall) had interruptions in radiotherapy and/or incomplete therapy. Altogether, 70.4% of surgical patients completed radiotherapy with no interruptions compared with 52.0% of nonsurgical patients ( 2 =78.17;P.001). Surgery was associated with an increased likelihood of completing uninterrupted radiotherapy for all tumor sites. Comorbidity, chemotherapy, and regional disease were all associated with a decreased likelihood of completing radiotherapy at a subset of sites. Conclusions: Failure to complete uninterrupted radiotherapy is common among Medicare enrollees with head and neck cancer. Surgery before radiotherapy is associated with an increased likelihood of completing radiotherapy. At a subset of sites, chemotherapy is associated with a decreased likelihood of completing radiotherapy. Further research is needed to identify factors associated with noncompletion of radiotherapy among nonsurgical patients and patients who receive chemotherapy. Arch Otolaryngol Head Neck Surg. 2009;135(9):860-867
