S608 How Colon Cancer Is Diagnosed in a FIT-Driven Public Safety-Net System

Introduction: Los Angeles County Department of Health Services (LADHS) screens for colorectal cancer (CRC) in average-risk people, 45-75, with fecal immunochemical testing (FIT), followed by diagnostic colonoscopy for those who test positive (FIT+). However, CRC often comes to attention via imaging or direct colonoscopy during investigation of patient symptoms. These non-FIT+ paths to CRC diagnosis reflect difficulties in healthcare access, inefficient FIT screening among enrolled patients, or other delays in care. Our aim was to understand the extent of CRC diagnosis using both FIT+ and non-FIT+ pathways. Methods: We conducted an observational retrospective cohort study of colorectal cancers diagnosed at Olive View-UCLA Medical Center (OVMC) in 2024 by correlating medical records with pathology and endoscopy databases. Outcomes included the proportion of CRC cases diagnosed via FIT+ versus non-FIT+ methods and symptoms present during diagnostic evaluation. Results: Fifty-three colorectal cancers were diagnosed at OVMC in 2024. Half the patients (27/53; 50.94%) were enrolled in the county insurance program. A third (20/53; 37.7%) completed a FIT test prior to diagnosis; most of these were insured patients (18/20; 90%). Twenty percent (4/20) of completed FIT tests were falsely negative. Only a third (5/16; 31.25%) of FIT+ results had colonoscopy within 6 months of the test. Almost all cases of CRC were diagnosed by colonoscopy (51/53, 96.2%) with 2 diagnosed after emergent surgery; 968 lower endoscopies were performed in 2024, often for CRC-related symptoms (n = 581) rather than FIT+ (n = 387). 5.3% of endoscopies resulted in CRC diagnosis (51/968); 4.1% of endoscopies done for FIT+ diagnosed CRC (16/387). The most common symptoms prior to diagnosis were lower GI bleeding (49.1%; 26/53), microcytic anemia (37.7%; 20/53) and abdominal pain (39.6%; 21/53), followed by abnormal imaging (34.0%; 18/53). True iron deficiency preceded the diagnosis of cancer in 22.6% (12/53) cases. Less common were reported changes in stool caliber (7.6%; 4/53) and family history of colon cancer (5.7%; 3/53). Conclusion: Our study demonstrates a major barrier to diagnosing CRC is patients who lack county insurance, as half the CRC patients were “outsiders” with no screening benefit. Colon cancers are diagnosed at OVMC at an annual rate that is at least 4-fold higher than expected in the general population (4.1% vs ∼1%), highlighting the strength of a FIT+ screening modality.