Interval colorectal cancers after negative faecal immunochemical test in a 13-year screening programme

Area of Science:

• Gastroenterology
• Oncology
• Public Health

Background:

• Colorectal cancer (CRC) screening programs aim to detect cancer early.
• The faecal immunochemical test (FIT) is a widely used screening tool.
• Understanding FIT sensitivity, especially for interval cancers, is crucial for program evaluation.

Purpose of the Study:

• To assess the sensitivity of the faecal immunochemical test (FIT) for cancer detection.
• To evaluate FIT performance over six rounds of biennial screening in a large population.
• To analyze interval colorectal cancer rates and their relationship with FIT sensitivity.

Main Methods:

• A population-based cohort of 123,347 individuals aged 50-69 was followed from 2002 to 2015.
• Four hundred forty-one thousand, six hundred forty-seven FITs were administered over six biennial screening rounds.
• Test sensitivity was calculated using the Proportional Interval Cancer Rate and Interval Cancer Proportion methods.

Main Results:

• An interval colorectal cancer incidence rate of 1.87 per 10,000 person-years was observed.
• Overall FIT sensitivity was 86.9% (Proportional Interval Cancer Rate) and 83.9% (Interval Cancer Proportion).
• Sensitivity was lowest in the first round and increased with subsequent screening rounds.

Conclusions:

• High FIT sensitivity (over 80%) is associated with a low incidence of interval colorectal cancers.
• FIT demonstrates effective cancer detection, highlighting its value in screening programs.
• Methodological differences in calculating sensitivity led to varying trends across screening rounds.