P0282 - Contribution of Diabetes to Gastrointestinal Cancers in Young Adults

Timothy A. Zaki, MD¹, Amit G. Singal, MD, MS¹, John M. Inadomi, MD², Caitlin C. Murphy, PhD, MPH^3
1University of Texas Southwestern Medical Center, Dallas, TX; ²University of Utah, Salt Lake City, UT; ³University of Texas Health Science Center at Houston, Houston, TX

Introduction: Incidence rates of several gastrointestinal (GI) cancers are increasing in younger adults. Diabetes is a risk factor for these cancers in older adults and now occurs at a greater frequency in younger adults than in decades past. Earlier-onset diabetes may contribute to increasing incidence rates of GI cancers in younger adults, whereby shifts in the age at diabetes onset translate into a large number of at-risk persons in the population. To test this hypothesis, we: 1) examined changes in the age distribution of diabetes-associated GI cancers and 2) estimated the generalized impact fraction for GI cancers related to diabetes.

Methods: We estimated mean age at diagnosis and age-specific incidence rates (20-49 years, 50-64 years, and ≥65 years) of colorectal, pancreas, and liver cancer during 1992–2018 using population-based data from the Surveillance, Epidemiology, and End Results program, by approximate 4-year periods. In parallel, we used data from the National Health and Nutrition Examination Survey to estimate the generalized impact fraction (GIF) for these cancers related to diabetes, representing the proportion of incident cancers attributable to increases in prevalence of diabetes from 1999-2000 to 2017-2018.

Results: From 1992-95 to 2016-18, mean age at diagnosis decreased for colorectal (from 69.8 to 65.2 years) and pancreas (from 70.2 to 69.5 years) cancer (both p< 0.01), and age-specific incidence rates increased for age 20-49 years (Figure 1). Age-specific rates of pancreas cancer also increased for ages 50-64 and ≥65 years, but rates of colorectal cancer decreased for these age groups. For liver cancer, mean age at diagnosis decreased from 64.7 years in 1992-95 to 63.0 years in 2004-07 but subsequently increased to 66.1 years in 2016-18 (p< 0.01); age-specific incidence rates also varied over time. Prevalence of diabetes increased from 1999-2000 to 2017-2018 for all age groups (Table 1). GIF of diabetes ranged from 0.3% (colorectal cancer, age 20-49 years) to 5.7% (pancreas cancer, age ≥65 years).

Discussion: The age distribution of diabetes-associated GI cancers did not uniformly decrease, and GIF ranged from 0.3% to 1.2% for age 20-49 years, suggesting diabetes may contribute little to increasing incidence rates of GI cancers in young adults. Alternative mechanisms, such as lifestyle factors, likely contribute to these patterns and warrant further study.


Figure: Figure 1. Age-specific incidence rates (20-49, 50-64, and ≥65 years) of colorectal (A), pancreas (B), and liver (C) cancer from 1992–2018, overlaid with mean age of diagnosis in each 4-year period

	Prevalence, 1999-2000	Prevalence, 2017-2018	Relative Risk	GIF (%)
Colorectal
20-49 years	0.02	0.03	1.26	0.25
50-64 years	0.11	0.15	1.26	0.95
≥65 years	0.14	0.20	1.26	1.72
Pancreas
20-49 years	0.02	0.03	1.94	0.90
50-64 years	0.11	0.15	1.94	3.21
≥65 years	0.14	0.20	1.94	5.70
Liver
20-49 years	0.02	0.03	2.31	1.24
50-64 years	0.11	0.15	2.31	4.32
≥65 years	0.14	0.20	2.31	7.6

Table: Table 1. Generalized impact fraction (GIF) for colorectal, pancreas, and liver cancer related to diabetes prevalence during the period 1999-2000 to 2017-2018


Disclosures:
Timothy Zaki indicated no relevant financial relationships.
Amit Singal indicated no relevant financial relationships.
John Inadomi indicated no relevant financial relationships.
Caitlin Murphy: Freenome – Consultant.


Timothy A. Zaki, MD¹, Amit G. Singal, MD, MS¹, John M. Inadomi, MD², Caitlin C. Murphy, PhD, MPH³. P0282 - Contribution of Diabetes to Gastrointestinal Cancers in Young Adults, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.