Of the 6,135 FIT-negative participants, 22.2% were in the less-than-3-years group, 28.9% 3-10 years, and 48.8% more-than-10 years-or-never group. The more-than-10-years group had a higher frequency of ACRN (14.7%) than did the 3-10-year group (0.4%) and the 0-3-year group (0.7%, P less than .001).
Among FIT-positive patients, the more-than-10-year group was at higher risk of ACRN diagnosis during follow-up colonoscopy than was the less-than-3-year group (adjusted OR, 3.63; 95% confidence interval, 2.48-5.31), but not compared with the 3-10-year group (aOR, 1.17; 95% CI, 0.71-1.93). The more-than-10-year group also was at greater risk of a CRC diagnosis than was the less-than-3-year group (aOR, 3.66; 95% CI, 1.74-7.73). There was no significant difference in CRC risk between the less-than-3-year group and the 3-10-year group (aOR, 0.58; 95% CI, 0.17-1.93).
The authors suggest that CRC and ACRN found in patients who had a colonoscopy in the past 3 years are likely to be lesions that were missed in the previous exam, rather than new, fast-growing lesions. That suggests that FIT may help catch lesions that were missed during earlier screenings, though just 2.1% of the less-than-3-year group and 1.6% of the 3-10-year group were diagnosed with CRC, and 10.9% and 12.6% with ACRN, respectively.
The authors conclude that it may not be appropriate to offer interval FIT to all patients, since it can lead to unnecessary colonoscopies. They call for more research to determine which categories of patients are most likely to benefit from interval FIT.
SOURCE: Kim NH et al. Gastrointest Endosc. 2019 Jan 23.