Beginning in 1973, the SEER registry program was established to identify all new cancer cases diagnosed in 7 geographic areas. By 1975, SEER included 9 geographic regions, 5 states (Connecticut, Hawaii, Iowa, New Mexico, and Utah) and 4 metropolitan areas (San Francisco–Oakland in California; Seattle–Puget Sound in Washington; Detroit, Michigan; and Atlanta, Georgia). In 1992, the Los Angeles County and San Jose–Monterey areas in California joined the SEER program, expanding the representation to approximately 14% of the U.S. population. Overall, the SEER population is similar to the general U.S. population, particularly in measures of poverty and education. However, SEER regions are more urban and have a higher proportion of foreign-born persons than the general U.S. population. Data for this study were obtained from SEER*STAT public-use data files (National Cancer Institute, Bethesda, Maryland), available on CD-ROM from the National Cancer Institute (7). Data from the SEER public-use CD-ROM were converted into SAS datasets for further analyses (SAS software, version 8.2, SAS Institute, Inc., Cary, North Carolina).