Stratifying colorectal cancer (CRC) risk based on hemoglobin concentration in fecal immunochemical testing (FIT) could be appropriate to guide screening intervals, a study found.
To analyze the dose-response association between fecal hemoglobin concentrations and the presence of advanced neoplasia, defined as CRC or advanced adenoma, researchers in Germany studied 7,398 patients undergoing CRC screening after a quantitative FIT. The analysis excluded participants younger than age 50 years and older than age 79 years and those with a history of CRC or inflammatory bowel disease, colonoscopy in the past five years, inadequate bowel preparation, incomplete colonoscopy, undefined polyp from colonoscopy findings, and stool sampling after colonoscopy.
Participants were categorized by FIT hemoglobin concentration (in μg/g): less than 1.7, 1.7 to less than 8, 8 to less than 9, 9 to less than 10, 10 to less than 12, 12 to less than 17, 17 to less than 25, 25 to less than 45, and 45 or greater. Advanced adenomas were defined as those 1 cm or greater, with tubulo- or tubulo-villous components, or high-grade dysplasia. The researchers assessed prevalence of any adenoma (advanced adenoma or CRC) and of large adenomas (≥1 cm). Subgroup analyses were done by sex and age (50 to 59 years vs. 60 to 79 years). The results were published as a brief research report by Annals of Internal Medicine on Nov. 7.
Forty-one percent of patients had hemoglobin concentrations less than 1.7 μg/g, and 81% had a result less than 8 μg/g. Ten percent had what is considered a positive FIT, with fecal hemoglobin concentrations greater than 17 μg/g. Prevalence of adenomas increased from 6% among those with hemoglobin concentrations less than 1.7 μg/g to 22% in the group of participants with the highest hemoglobin concentration still considered a FIT-negative result. That compares to up to 51% among participants with FIT-positive results. Results were similar in subgroup analyses of large adenomas and subgroup analyses by age and sex.
The results show that patients with hemoglobin concentrations in the upper range for a negative FIT result are at higher risk for CRC than those with negative values in the lower range, potentially indicating a benefit from personalized screening intervals. “Our results may help to develop risk-adapted FIT-based screening whose (cost-)effectiveness should be evaluated by modeling studies and screening trials,” the study authors wrote.