Elderly breast and colorectal cancer patients' clinical course: patient and contextual influences.

BACKGROUND: The social and medical environments that surround people are each independently associated with their cancer course. The extent to which these characteristics may together mediate patients' cancer care and outcomes is not known.
METHODS: Using multilevel methods and data, we studied elderly breast and colorectal cancer patients (level I) within urban social (level II: ZIP code tabulation area) and health care (level III: hospital service area) contexts. We sought to determine (1) which, if any, observable social and medical contextual attributes were associated with patient cancer outcomes after controlling for observable patient attributes, and (2) the magnitude of residual variation in patient cancer outcomes at each level.
RESULTS: Numerous patient attributes and social area attributes, including poverty, were associated with unfavorable patient cancer outcomes across the full clinical cancer continuum for both cancers. Health care area attributes were not associated with patient cancer outcomes. After controlling for observable covariates at all 3 levels, there was substantial residual variation in patient cancer outcomes at all levels.
CONCLUSIONS: After controlling for patient attributes known to confer risk of poor cancer outcomes, we find that neighborhood socioeconomic disadvantage exerts an independent and deleterious effect on residents' cancer outcomes, but the area supply of the specific types of health care studied do not. Multilevel interventions targeted at cancer patients and their social areas may be useful. We also show substantial residual variation in patient outcomes across social and health care areas, a finding potentially relevant to traditional small area variation research methods.