Is There an Increased Risk of Proximal Gastrointestinal Cancer After a Positive Fecal Immunochemical Test?

The fecal immunochemical test (FIT) is a simple, noninvasive, at-home study that detects blood in the stool and is used for colon cancer (CRC) screening in average-risk individuals. Emerging data suggest that patients with a positive FIT may have an increased risk of proximal gastrointestinal cancer, which includes the esophagus, stomach, and small bowel. This large, retrospective U.S. cohort study evaluated patient risk of developing proximal GI cancer less than 3 years after a positive or negative FIT result. 

Investigators extracted data from the Optum Clinformatics DataMart Database, enrolling a total of 153,203 patients aged 50 to 61 years, including 9572 (6.24%) FIT-positive patients, 122,803 (80.16%) FIT-negative patients, and 20,828 (13.60%) patients without an available FIT result. Baseline characteristics were similar among all 3 groups. 

Of the patients included in the study, 127 (0.08%) developed proximal GI cancer within 3 years of a FIT: 24 (0.25%) in the FIT-positive group and 84 (0.07%) in the FIT-negative group (P<.0001) as well as 19 (0.09%) without an available FIT result. The adjusted hazard ratio (aHR) for proximal GI cancer in individuals with a positive FIT versus negative FIT was 3.02 (95% confidence interval [CI], 1.89-4.82). 

Proximal GI cancer risk was significantly higher in FIT-positive patients with CRC (1.50%; 95% CI, 0.18%-5.29%) versus FIT-positive patients without CRC (0.23%; 95% CI, 0.15%-0.35%) (P<.001). In FIT-positive patients, CRC versus no CRC had an aHR of 5.10 (95% CI, 1.18-21.96) for proximal GI cancer, and colorectal neoplasia (CRN=polyps and cancer) versus no CRN was associated with an aHR of 1.92 (95% CI, 0.86-4.29). Among FIT-negative patients, CRC versus no CRC was associated with an aHR of 11.40 (95% CI, 1.58-82.06) for proximal GI cancer, and CRN versus no CRN was associated with an aHR of 1.69 (95% CI, 0.89-3.19).