Colonoscopy screening among Americans with a family history of colorectal cancer

Background: Colorectal cancer (CRC) is the second leading cause of cancer deaths, with an estimated annual incidence rate of 46.3 /100,000. CRC incidence has increased by 1.7% annually since 1992 among adults aged <50 years. Persons with a family history of CRC have increased risk (20% of newly-diagnosed CRC patients report first degree relative(s) with CRC) and CRC patients with a family history are younger than the average CRC patient. Majority of CRCs in persons with a family history follow the conventional adenoma-cancer pathway, suggesting high protective potential of colonoscopy screening. Consequently, the American College of Gastroenterology recommends initiation of 5-yearly colonoscopy screening at 40 years of age for persons with a CRC family history. Because 20% of the 150,000 incident CRC cases consists of first degree relatives of CRC patients, an important public health strategy to reduce CRC rates may be to target outreach efforts to this higher-risk sub-group, if current screening rates are inadequate. This study will explore whether Americans with a positive family history are more likely to have had colonoscopy than those without a family history, and whether the trend has changed over time. Methods: To study colonoscopy screening rates (crude and age-sex-race adjusted) among 40-plus aged adults with a family history of CRC compared to persons aged 50-75 years without a family history (stratified into 50-64 and 65-75 years), using the National Health Interview Surveys of 2010, 2005 and 2000. We will also examine time trends and the role of insurance status. Preliminary results: Of 9,482 NHIS 2010 survey respondents who answered the questions on CRC family history, 13.5% reported a family history, of whom 51.3% had a colonoscopy. Among 40-49 age groups with family history, 39.2% had colonoscopy compared to 48.0% among 50-75 year olds without family history. Sample distribution (1,661, 3,275 and 1478 aged 40-49 years, 50-64 years, and 65-75 years, respectively) shows adequate statistical power for research. Conclusion: Colonoscopy screening has poor acceptance among low-risk population, 48.0% among 50-75 year olds without family history of CRC. A large proportion (60% of younger persons) with a family history of CRC have not undergone colonoscopy, although 20% of CRC cases arise among them. Additional analyses will provide evidence regarding the potential gains of targeting this higher risk group for overall CRC incidence reduction. This group may be more receptive to colonoscopy than low-risk individuals because of their personal encounter with CRC.