Tailoring fecal immunochemical tests positivity thresholds by age and sex may help to optimize colorectal cancer screening

1. Cancer detection among participants was higher with lower positivity thresholds.

2. Sensitivity with conventional fecal immunochemical tests (FIT) thresholds decreased with increasing age and female gender.

Evidence Rating Level: 2 (Good)

Study Rundown: FIT directly measure human hemoglobin concentrations in the stool commonly and are commonly used for colorectal cancer screening. Despite demographic variations in stool hemoglobin concentrations, there is limited data regarding optimal positivity thresholds by age and sex. The authors of this study aimed to identify programmatic (multitest) FIT performance characteristics and optimal FIT quantitative haemoglobin positivity thresholds. They observed that tailoring FIT positivity thresholds by age and sex might help to optimize colorectal cancer screening programs. A major limitation of this study was that the authors did not have quantitative FIT values available for all participants during the study interval. However, a strength of this study included its large-scale sample size.

Click to read the study in Annals of Internal Medicine

Relevant Reading: Optimizing Colorectal Cancer Screening by Race and Sex: Microsimulation Analysis II to Inform the American Cancer Society Colorectal Cancer Screening Guideline

In-Depth [retrospective cohort]: The authors of this study conducted a retrospective cohort analysis to evaluate FIT positivity thresholds and performance characteristics. A total of 640 859 patients were included in the study who completed a baseline FIT and were followed for 2 years. Of these patients, it was observed that cancer detection sensitivity increased at lower positivity thresholds. Specifically, it increased from 822 in 1245 (66.0%) at 30 µg/g to 925 (74.3%) at 20 µg/g and 987 (79.3%) at 10µg/g. Further, the authors observed that FIT had lower sensitivity and specificity for women at all thresholds from 10-30µg/g compared to men. Based on the results of the study, the researchers recommended that screening programs wishing to increase cancer detection by lowering their positivity thresholds will require substantial additional colonoscopy and financial resources.

Image: PD

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