Abstract PR014: FIT for red flag signs and symptoms of early onset colorectal cancer: low value or viable diagnostic tool?
Bibliographic record
Abstract
Abstract Purpose: Early-onset colorectal cancer (EOCRC) incidence is rising in a predominantly symptomatic population of young adults. Effective triage tools are needed to identify high-risk individuals in this relatively low incidence population. We examined fecal immunochemical test (FIT) use among adults ages <50 with red flag signs and symptoms for EOCRC and evaluated whether FIT use is predictive of EOCRC risk. Methods: Retrospective cohort study of US Veterans (ages 18-49) receiving Veterans Health Administration (VHA) care during 1999-2022 with a documented EOCRC red flag sign or symptom (abdominal distension, abdominal pain, anemia [non-specific and iron-deficiency], change in bowel habits, constipation, diarrhea, hematochezia, nausea/vomiting) based on International Classification of Diseases, 9th (ICD-9) or 10th (ICD-10) Revision codes, or lab results. The primary exposure was FIT uptake and result, documented via lab results, shown as a three-level variable (no FIT use, negative FIT or positive FIT). The primary outcome was EOCRC diagnosis, derived from linkages to the VA Oncology Domain and National Death Index. Covariates included age at symptom presentation, sex, race and ethnicity, and number of symptoms within 60 days of first symptom presentation. Participants entered the study at first symptom onset and were followed until the first of: incident or fatal EOCRC diagnosis, non-EOCRC-related death, 2 years follow-up, age 50 or December 31, 2022. We derived cumulative CRC incidence estimates using Kaplan-Meier estimation. Multivariable, mixed-effects Cox regression models were used to estimate adjusted hazard ratios (aHR) and 95% confidence intervals (CI) for CRC risk among those who received a FIT test. Results: Among 751,116 Veterans, 38,019 (5.1%) received a FIT. The most common symptoms yielding a FIT were abdominal pain (29.6%), anemia (20.4%), hematochezia (18.5%), and diarrhea (16.4%). Approximately 76% of patients who received a FIT had one symptom at presentation. Among 38,019 patients who received a FIT, 6,191 (16.3%) had a positive finding. Approximately 1,295 (21%) of 6,191 FIT-positive patients received a diagnostic colonoscopy compared to 46,693 (6.6%) of 713,097 non-FIT patients. After two years of follow-up, patients with a positive FIT had a 1.44% cumulative EOCRC incidence (95% CI: 1.12%-1.77%), compared to a 0.12% among those with a negative FIT (95% CI; 0.08%-0.16%) and 0.12% among those who did not receive a FIT (95% CI: 0.12%-0.13%). The findings correspond to an aHR for EOCRC of 12.81 (95% CI: 8.47-19.36) for FIT-positive patients compared to those with a negative FIT. Conclusions: Among adults ages 18-49 presenting with a red flag sign or symptom to VHA care, FIT use was low. However, a positive FIT result was linked to a substantially elevated EOCRC risk relative to a negative result. To address potential concerns about generalizability, future research should confirm whether systematic use of FIT as a clinical triage tool could help identify symptomatic adults at high EOCRC risk who need a diagnostic colonoscopy. Citation Format: Daniel Sabater Minarim, Kylie Morgan, Lin Liu, Matthew P. Banegas, Maria Elena Martinez, Samir Gupta, Josh Demb. FIT for red flag signs and symptoms of early onset colorectal cancer: low value or viable diagnostic tool? [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: The Rise in Early-Onset Cancers—Knowledge Gaps and Research Opportunities; 2025 Dec 10-13; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(23_Suppl):Abstract nr PR014.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.018 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".