Patient characteristics
Age at diagnosis was categorized into 5-year intervals and race recorded
as white, black, and other. Year of diagnosis was stratified into four
time periods: 1992–1996, 1997–2001, 2002–2005, and 2006–2009. The
SEER marital status variable was recorded as married, not married, and
unknown. An aggregate socioeconomic status (SES) score was calculated
from meducation, poverty level, and income data from the 2000 census tract
data, as previously reported by Du and colleagues . Patients' scores
were ranked on a scale of 1–5 by the use of the formula that incorporated