ASPO Abstracts
Young onset colorectal cancer risk among individuals with iron deficiency anemia and hematochezia
Category: Early Detection & Risk Prediction
Conference Year: 2020
Abstract Body:
Purpose: Examine the association between iron deficiency anemia (IDA) and the risk of young-onset colorectal
cancer (YCRC), as well as hematochezia and the risk of YCRC.
Methods: Retrospective cohort study of US Veterans (ages 18-49) during 1999-2016. An analytic cohort for IDA
was created by matching individuals with IDA (identified via lab result) to four patients without IDA on sex, birth
year, and first visit date (n=240,650). We used the same approach to create a second analytic cohort of patients
with hematochezia (identified via diagnoses codes), matched to patients without hematochezia (n=653,740).
Primary outcome for each analytic cohort was incident YCRC ascertained via cancer registry and/or National
Death Index cause specific mortality data. We derived cumulative incidence and risk differences (RD) using
Kaplan-Meier estimation and Cox regression models to estimate hazard ratios (HR) and corresponding 95%
confidence intervals (CI) for YCRC.
Results: Five-year cumulative incidence of YCRC was 0.43% among patients with IDA compared to 0.04% among
those without (RD: 0.39%, 95% CI 0.34%-0.44%), corresponding to a hazard ratio of 12.32 (HR: 12.32, 95% CI:
9.19-16.53). Among individuals with IDA, RD varied by sex and age: 0.78% for men (95% CI: 0.65%-0.91%) and
0.08% for women (95% CI: 0.04%-0.12%); 0.14% for <30 years (95% CI: 0.05%-0.26%), 0.19% for 30-39 years
(95% CI: 0.11%-0.27%), and 0.52% for 40-49 years (95% CI: 0.43%-0.63%), compared to individuals without IDA.
In analyses on hematochezia, the cumulative incidence was 0.33% among patients with hematochezia compared
to 0.03% among those without (RD: 0.30%, 95% CI 0.26-0.33%), corresponding to a hazard ratio of 10.61 (HR:
10.61, 95% CI: 8.72-12.92). Among individuals with hematochezia, RD varied by sex and age: 0.31% for men
(95% CI: 0.27%-0.35%) and 0.21% for women (95% CI: 0.14%-0.29%); 0.04% for <30 years (95% CI:
0.01%-0.08%), 0.15% for 30-39 years (95% CI: 0.10%-0.19%), and 0.43% for 40-49 years (95% CI:
0.38%-0.49%), compared to individuals without hematochezia.
Conclusions: Risk of YCRC was substantially higher among Veterans with IDA or hematochezia, compared to
those without these conditions. For young adults with IDA or hematochezia, colonoscopy should be strongly
considered.
Keywords: colorectal cancer, young onset, iron defiency anemia, hematochezia, epidemiology