Year of Publication



Public Health

Date Available


Degree Name

Dr. of Public Health (Dr.P.H.)

Committee Chair

Steven T Fleming

Committee Member

Jaclyn McDowell

Committee Member

Warren J Christian


Background: Colorectal cancer (CRC) is the third most common type of cancer and the third most common cause of cancer death among men and women in the United States.1-3 The American Cancer Society estimates that there will be 147,950 new cases of CRC and 53,200 CRC related deaths in the U.S. for the year 2020.3 Kentucky CRC incidence for 2012-2016 was the highest in the nation, and the mortality rate for years 2013-2017 was ranked 5th in the nation.4-6 Risk factors for CRC include lifestyle factors, genetics, and disease status (comorbidities and treatment).2, 7 Diabetes has been found to be the most prevalent comorbidity among CRC patients, and the risk of developing CRC in patients with diabetes is 25% higher than those without diabetes.8, 9

Aim: The purpose of this study is to explore if comorbidities impacts CRC progression, CRC outcomes, and the development of second primary malignancy among CRC patients age 18 and older in Kentucky diagnosed between January 1, 2003 and December 31, 2016.

Methods: Two studies were performed using CRC data from Kentucky Cancer Registry, one was a retrospective cohort study and the other was a case control study. There were 20,571 cases included in the cohort study with the primary outcomes was all-cause mortality, CRC mortality, and second primary cancer. There were 18,170 total, 9,085 cases and controls in the second study. This study examined the geographical distribution of late-stage CRC and comorbidities.

Results Chapter 3: Logistic regression models show that comorbidities increased the odds of death or late-stage CRC. The Cox proportional hazard models of all-cause and CRC mortalities and second primary show that comorbidities, patient factors, and treatments can be protective or increase the hazards of dying or having a second primary cancer. The Kaplan Meier curve demonstrates the survival of early-stage at diagnosis CRC versus late-stage at diagnosis CRC.

Results Chapter 4: The geographical distribution maps of the four positively associated morbidities (electrolyte disorders, liver disease, weight loss, and deficiency anemia) do not demonstrate any patterns resembling the cluster, the comorbidity distribution appears to be random. The map of comorbidities among CRC patients show that a large percentage experience a burden of two or more comorbidities.

Conclusion: The results indicate that comorbidities do play a role in the stage of CRC diagnosis, with the data showing greater odds of being diagnosed with early-stage cancer for many of the individual comorbidities. The space-time analysis found a significant high rate cluster of late-stage CRC, however, mapping the distribution of positively associated comorbidities did not demonstrate a pattern matching the cluster. Further research is needed to examine the impact of comorbidities and CRC stage at diagnosis.

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