Outcome and predictors

The primary outcome was 5-year OS, defined as the time from the date of diagnosis to the date of death, or the last contact if the patient was still alive or lost to follow-up (the time was censored). The primary predictor was time-to-treatment, defined as the period between diagnosis and initiation of any first-course treatment. Time-to-treatment was categorized based on the commonly recommended time-to-treatment and the proposed recommendation in the US (within the first 4 weeks and 6 weeks after diagnosis, respectively) (14). The categories of time-to-treatment were: (I) 0 day, (II) 1 day to 4 weeks, (III) 4.1–6.0 weeks, and (IV) >6 weeks, with 1 day to 4 weeks as the reference group. We distinguished 0 day from the 1 day to 4 weeks on the assumption that patients who received treatment on the same day of diagnosis might harbor specific conditions different from other patients (e.g., have less severe symptoms and were thus eligible for prompt tumor removal or require an emergent procedure). The covariates adjusted in the analysis were age at diagnosis, sex, race, urban/rural status, distance to the reporting hospital, primary payer, facility type, stage at diagnosis, histology, treatment type, and Charlson-Deyo comorbidity score because those variables can affect both decision on timing of treatment and patient survival. Detailed information about how variables in the NCDB are defined by the American College of Surgeons is provided elsewhere (19). The NCDB contains data from the participating hospital cancer registries.