Subject loss in spatial analysis of breast cancer.

Possible selection bias from assignment of latitude-longitude coordinates to the place of residence of all Connecticut women diagnosed with breast cancer from 1992 to 1995 (N = 11,470) was evaluated. Exact address-matching was accomplished for 8,121 records (70.8%) and an additional 1,722 records (15.0%) were matched using relaxed criteria. We did not address-match 1,627 records (14.1%) due to missing address information or limitations of the Geographic Information Systems street file. The age-adjusted likelihood of address-matching records was significantly greater for women of color, those born within Connecticut, residents of urban locales or census tracts with low median family incomes and those cases diagnosed nearer to 1992. Few differences in address-matching were attributable to tumor characteristics or therapeutic modality.