Colorectal cancer (CRC) is the fourth most common cancer in the United States and the secondleading cause of cancer deaths. Despite declines in CRC incidence rates, survival following diagnosis hasimproved only modestly over the past few decades. Even though environmental contexts play an importantrole in health, disease, and behavior, most studies about CRC survival have largely ignored the geographicvariation and importance of area-level socioeconomic conditions that have been associated with CRCscreening, CRC stage at diagnosis, and with the survival of many other cancers. CRC patients who live inareas with worse socioeconomic conditions have decreased survival than those who live under more affluentconditions; however, the mechanisms by which these area-level factors exert their influence on CRC survivalremain unclear. This amended application of the proposed population-based, prospective study has three specific aims.
Aim 1) Determine the extent of the geographic variation of CRC survival across the United States based onsmall geographic areas at the sub-county (census-tract) level using the linked Surveillance, Epidemiology, andEnd Results (SEER)-Medicare data for over 100,000 men and women aged 66 or older diagnosed with CRC.
Aim 2) Determine the extent to which lower CRC survival can be explained by higher area socioeconomicdeprivation among persons age 66 and older.
Aim 3) Identify potential mediating pathways by which higherarea socioeconomic deprivation is associated with lower CRC survival among persons age 66 and older,namely a) patient characteristics, b) physician and hospital characteristics, c) tumor characteristics, d) type oftreatment received, and e) surveillance for CRC after diagnosis to detect recurrence and metastases. A multilevel spatial model will be developed to address the specific aims of the proposed study. We willuse the following existing data sources: 1) 1992-2005 data from NCI's SEER program (survival, patientcharacteristics, type of treatment, tumor characteristics); 2) 1991-2005 Medicare data (patient characteristics,type of treatment, surveillance after diagnosis) which is linked to the SEER data; 3) 1991-2005 data from theProvider of Services File (hospital and physician characteristics), 4) 1990-2005 census data (area deprivationmeasures), and 5) Medicare Current Beneficiary Survey data. Advanced Bayesian spatial analyses of CRCsurvival will be performed and a geographic information system will be used to display the results. Our studywill increase understanding of and identify important mechanisms of the role of area-level socioeconomicdeprivation on CRC survival. In addition, this study will help provide opportunities for targeting specificgeographic areas to allocate resources and interventions locally to improve CRC survival using evidence-based approaches, thereby reducing health disparities associated with living in socioeconomically deprivedareas.
Colorectal cancer is the second leading cause of cancer deaths. To reduce geographic disparities in survivalfollowing colorectal cancer and to develop and implement interventions that can be targeted locally; it isimperative to identify reasons for lower-than-expected survival.
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