Patient demographics

Patient’s age at diagnosis, gender, race, type of health insurance, geographic location, education, median income quartile, treatment facility type were available for analysis. Geographic location was determined by the zip code of the patient’s residence recorded at the time of diagnosis. This was then classified and compared as metropolitan, urban, or rural location. Level of education for each patient was inferred by using the patient’s zip code at the time of diagnosis and with the aid of US census data, determined the number of adults in the patient’s zip code who did not graduate from high school. Patient level of income was estimated by matching the patient’s zip code to the median household income for the area of residence derived from US Census data. Treatment facility was categorized as academic/research center (post-graduate medical education training program and participation in cancer clinical research), which includes National Cancer Institute (NCI) designated comprehensive cancer center, or non-academic which includes community cancer program (more than 100 but ≤500 of new annual cancer cases) and comprehensive community cancer program (more than 500 new annual cancer cases). Charlson-Deyo score was used as a surrogate marker for patient co-morbidities. Charlson-Deyo score was categorized as 0, 1, or 2, and above to indicate increasing levels of comorbid conditions (12).