Interval Advanced Adenomas and Neoplasia in Patients with Negative Colonoscopy Following Positive Stool-Based...

Fecal occult blood test (FOBT) and fecal immunohistochemical test (FIT) are used for colorectal cancer (CRC) screening. However, when no adenomas are found following a positive FOBT/FIT, the future risk of advanced adenomas or colorectal cancer (CRC) is unclear. We determined the incidence and determinants of advanced adenomas or CRC after a negative index colonoscopy following a positive FOBT/FIT.

We identified patients in the Harris Health System (Houston, Texas) who underwent a colonoscopy following a positive FOBT/FIT from 01/2010 to 01/2013. We compared the incidence rates of advanced adenomas (≥ 1 cm, villous histopathology, or high-grade dysplasia) or CRC through 12/2023 for patients without polyps on index colonoscopy (negative colonoscopy) to patients with polyps (positive colonoscopy). We examined risk factors for incident adenomas using Cox regression models.

Of 2096 patients, 1293 (61.7%) had negative index colonoscopy and 803 (38.3%) had positive index colonoscopy. Overall, 411 patients (19.6%) underwent subsequent colonoscopy with incident adenomas in 241 patients and no incident CRC over mean 12.5 years. The incidence rate of advanced adenomas was 2.08 per 100 person-years after positive index colonoscopy compared to 0.65 per 100 person-years after negative index colonoscopy (age-adjusted incidence rate ratio 3.08, 95% CI 1.27-7.48). Non-Hispanic white race was the strongest risk factor for incident adenomas among patients with negative index colonoscopy.

We found a low likelihood of advanced adenomas and no interval CRC following negative index colonoscopy after positive FOBT/FIT. Non-Hispanic white race was a risk factor for incident adenomas, and these patients may warrant closer surveillance.