Association of time to colonoscopy after a positive fecal test result and fecal hemoglobin concentration with risk of advanced colorectal neoplasia

Background

We evaluated the risk of advanced colorectal neoplasia (ACRN) and colorectal cancer (CRC) according to time to colonoscopy after positive fecal immunochemical test (FIT), fecal hemoglobin concentration, and combination of both.

Methods

We analyzed the records of 2362 patients aged ≥50?years who underwent colonoscopy because of a positive FIT result through the National Cancer Screening Program of Korea.

Results

ACRN risk increased with increasing time to colonoscopy after a positive FIT (17.2%, 18.6%, 19.1%, 21.4%, and 27.2% in <30, 30–59, 60–149, 150–179, and ≥180?days; P?=?0.034), and ACRN and CRC risk increased with increasing fecal hemoglobin concentration (ACRN, 13.2%, 16.9%, 18.5%, 23.2%, and 26.6%; CRC, 1.3%, 1.7%, 4.7%, 5.7%, and 12.8% with 100–200, 200–300, 300–500, 500–1000, and ≥1000?ng Hb/mL; both P?<?0.001). Even after adjusting for confounders, follow-up after 180?days tended to be associated with a higher ACRN risk (adjusted odds ratio, 1.73; 95% confidence interval [CI], 0.91-3.27), compared with follow-up colonoscopy at <30?days, and fecal hemoglobin 500–1000, and ≥1000?ng Hb/mL were associated with a significantly higher ACRN and CRC risk, compared with 100–200?ng Hb/mL. Moreover, the group with ≥180?days and ≥1000?ng Hb/mL had a much higher CRC risk compared with the group with <180?days and <1000?ng?Hb/mL (12.45-fold; 95% CI, 3.73–41.57).

Conclusions

Patients with positive FIT results, especially those with higher fecal hemoglobin levels, should undergo timely follow-up colonoscopy.