Geographic Disparities in Survival of Early-Stage Colorectal Adenocarcinoma for Patients Undergoing Colon Resection: a U.S. Population-Based Study Open Access

Okafor, Maureen Obianuju (2016)

Permanent URL: https://etd.library.emory.edu/concern/etds/n583xv533?locale=en
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Abstract

Geographic Disparities in Survival of Early-Stage Colorectal Adenocarcinoma for Patients Undergoing Colon Resection: a U.S. Population-Based Study

By Maureen Obianuju Okafor

Introduction: Colorectal cancer is the third most commonly diagnosed cancer and the second leading cause of cancer death among both men and women worldwide. Based on scientific evidence, limited access to care for patients living in remote rural areas or in small urban areas far from healthcare services is associated with poorer health outcomes. In order to better understand the importance of geographic differences and CRC patient care in the United States, this study seeks to investigate the geographic disparity in the survival of early-stage colorectal adenocarcinoma following surgery.

Materials and methods: A U.S. population-based retrospective cohort study using data from the Surveillance, Epidemiology, and End Results (SEER) Program was conducted. We identified 54,482 eligible cases of colorectal adenocarcinoma diagnosed between 2007 and 2011 from the 18 SEER cancer registries. To assess the differences in survival of colorectal adenocarcinoma by geographic location and the U.S. Census regions, Kaplan-Meier survival curves and multivariate Cox proportional hazard models were constructed. We presented the results of our multivariate analysis as adjusted hazard ratios (HR) with corresponding 95% confidence intervals.

Results: Kaplan-Meier survival curves and 5-year relative survival estimates indicated significantly better outcomes in metro counties (92%) compared to non-metro adjacent (87.3%) and non-metro non-adjacent areas (89.6%). Although insignificant, we found it surprising that the adjusted hazard ratio for non-metro non-adjacent areas compared to metro areas was higher than that for non-metro adjacent areas. A statistically non-significant 10% increase in the risk of death from colorectal adenocarcinoma was observed among cases in non-metro adjacent areas compared to those in metro counties (HR: 1.10, 95% CI: 0.97, 1.24). No substantial difference in cancer-specific mortality risk was found between metro and non-metro non-adjacent areas (HR: 1.04, 95% CI: 0.90, 1.20). Age at diagnosis, marital status and cancer stage were found to be strong predictors of survival in the United States.

Conclusion: There is a growing need for further research studies which will take into account geographic characteristics that aid in assessing access to and use of healthcare services among cancer patients, and ultimately, provides value towards improved health outcomes.

Table of Contents

TABLE OF CONTENTS

List of Tables .........................................................................................................viii

List of Figures ........................................................................................................viii

Chapter 1. Literature Review ....................................................................................1

Colorectal Cancer...................................................….........................................1

Epidemiology.....................................................................................................1

Risk Factors......................................................................................................3

Prevention ............................................................................... . .......................3

Diagnosis and Treatment Modalities.......................................................................4

Geographic Differences in Colorectal Cancer Survival................................................5

Rural-Urban Classifications and Access to Colorectal Cancer Care... .. .... . . . ...................6

Rationale and specific aims..................................................................................8

Chapter 2. Manuscript ............................................................................................10

Introduction....................................................................................................10

Materials and Methods....................................................................... . ..............12

Data Source ............................... .. .................................... .. ......... ............12

Study Population ......................................................................................12

Study Variables ........................................................................................14

Statistical Analysis ....................................................................................16

Results...........................................................................................................17

Demographic and Cancer Characteristics ......................................................17

Survival Analysis.......................................................................................18

Multivariate Analyses of Cancer-Specific Mortality ...........................................19

Discussion........................................................................................................20

Strengths and Limitations ...........................................................................24

Chapter 3. Conclusion ........................ .. ....................................................................27

Public Health Implications....................................................................................27

Future Recommendations....................................................................................27

References...............................................................................................................29

Tables and Figures.......... .. ............ .. ...........................................................................34

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