Background: Rural residence has been associated with increased risk of late stage cancer diagnosis, but it is unknown if this is related to lower socioeconomic status (SES) of rural residents or to other factors. This study examined the impacts of SES and urban/rural status on colorectal cancer (CRC) stage at diagnosis in California.
Methods: Cases of CRC among persons >or=50 years of age diagnosed from 1988-2000 were obtained from the California Cancer Registry. A composite census based SES measure was used in the analysis, and the RUCA (Rural Urban Commuting Areas) classification scheme was used to categorize the residence at diagnosis as urban, large town, or small town. Multivariate logistic regression was used to examine the association between SES, urban/rural status, and late stage at diagnosis.
Results: In multivariate models, SES had the strongest association with stage at diagnosis among individuals living in urban areas. As SES level increased, odds of late stage at diagnosis decreased. Individuals in the highest SES category had lower odds of being diagnosed at late stage when compared with those in the lowest SES category (O.R. = 0.91, 95% C.I. = 0.87, 0.94). For individuals who lived in large towns and small rural towns, SES was not significantly associated with stage at diagnosis. We found no significant differences in stage at diagnosis by urban/rural status within SES categories.
Conclusions: These data suggest that the relationship between SES and the risk of late stage colorectal cancer varies among rural and urban populations. Further research into the factors that influence access to and utilization of colorectal cancer screening in rural areas is needed.