In February 2019, Fight Colorectal Cancer (Fight CRC) convened researchers from around the world to identify and prioritize what is causing the dangerous rise in cases of early-age onset colorectal cancer (EAO CRC). 

Since that meeting, the EAO CRC working group has published a meeting summary and a commentary in Gastro, reconvened in smaller groups at conferences such as Digestive Disease Week (DDW), and is currently planning a symposium in Madrid, Spain with working group member, Dr. Jose Perea. Working group members are also leading research in their respective fields. 

This is part two of a five-part series highlighting different areas of research being conducted by Fight CRC working group members to understand where the science is headed, and what it means for our community of patients.

Summary of the Research: Risk Factors for Early-Age Onset Colorectal Cancer

This case-control study of veterans aged 18-49 in the United States compared veterans with and without diagnosis of colorectal cancer. Researchers identified early-age onset colorectal cancer cases between 1999 and 2014 through a national cancer registry and collected data on age, weight, sex, race/ethnicity, body mass index (BMI), diabetes, smoking status, and aspirin use. These cases were compared to a group who had usual care colonoscopy without colorectal cancer diagnosis within the same time period.

Researchers identified 651 EAO CRC cases, and 67,416 controls. The average age of all individuals was 45 years old, and 82% were male. Of those who were diagnosed with CRC, a higher proportion were males, current smokers, non-aspirin users, and had lower BMIs.

Aspirin use and being overweight/obese were associated with decreased odds of early-age onest CRC. Weight loss of five kilograms within five years before a colonoscopy increased the odds of developing CRC. 

This finding highlights how unexplained weight loss should be a clinical sign that triggers a diagnostic assessment of early-age-onset CRC.

In order to better understand what this research means for EAO CRC, we interviewed Dr. Josh Demb, a postdoctoral fellow at the University of California San Diego (UCSD), who led part of this work.

Why is This Work Impactful?

The paper is impactful primarily because of the lack of prior research on risk factors in early-age-onset CRC. Our goal was to better contextualize the association between traditional CRC risk factors and early-onset CRC odds, which could help us identify similarities and differences between early-age-onset CRC and later-onset CRC.  

As prior studies dealt with sample size issues or a lack of risk-factor data, particularly for modifiable risk factors such as diabetes and body weight, we felt that our cohort within the VA system was well-positioned to address this knowledge gap.

What Does This Mean for the Debate About the Screening Guideline?

Relevant to the ACS guidelines that advocated for screening starting at 45, our study found that 75% of the cases in our study population were diagnosed between the ages of 40-49.  This could imply that screening earlier might detect a substantial proportion of early-age-onset CRC cases. However, more research is needed to determine the best strategy for identifying individuals under 50 who might benefit from screening.

What Do You Advise Patients and Advocates to Learn/Know About the Work, and What is Their Role in Considering the Impact of this Paper?

In addition to our main findings showing some similarities in risk factors between early-age-onset CRC and later-onset CRC (persons with increasing age and men have higher odds of EAO CRC), we also think it is important that patients and advocates be aware of possible warning signs. 

Notably, our study found that weight loss of 5kg or more within five years before a baseline colonoscopy was associated with increased early-age-onset CRC odds. This finding highlights how unexplained weight loss should be a clinical sign that triggers a diagnostic assessment of early age onset CRC. While the primary aim of our project was to look at possible risk factors that could be modified to lower risk of early-age-onset CRC, knowing possible signs and symptoms can also help ensure people are staying vigilant about their health. 

As patients and advocates learn about this work, their impact can be best felt by identifying where they still see information gaps. While this study provides key information, there is still a lot of work to be done to more comprehensively understand early-age-onset CRC risk factors. Patients and advocates can help identify particular areas that can be addressed, which can further guide where research might go.

Stay tuned for part 3!

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