Anatomical location of colorectal neoplasia in patients with positive stool tests (mt-sDNA or FIT): Data from the New Hampshire Colonoscopy Registry.

Background And Aims: Data comparing the location of polyp yield in patients with positive stool tests can aid screening test selection. We conducted a cross sectional analysis of New Hampshire Colonoscopy Registry data to compare the location, left versus right side of the colon, of neoplasia detected on colonoscopy following a mt-sDNA+ or FIT+ test as compared to a reference group having colonoscopy without a stool test.

Methods: Our outcomes were advanced lesions (adenoma and/or serrated polyp, including cancer), advanced adenomas (AA), or advanced serrated polyps (ASP), stratified by location. We examined left vs right side lesion prevalence across three cohorts.

Results: When compared to colonoscopy (n=68,645), both FIT+ (n=584) and mt-sDNA+ (n=1,176) patients had higher proportions of advanced lesions and AAs on both colon sides (<0.001). Mt-sDNA+ patients had significantly higher risks for right-sided advanced serrated polyps (OR:3.21:95%CI:2.67-3.85;colonoscopy (reference)) and right-sided advanced lesions (OR:3.13;95%CI:2.66-3.68;colonoscopy (reference)) as compared to FIT+ (ASP: OR:1.38;95%CI:0.99-1.99 and advanced lesions: OR:1.84;95%CI:1.43-2.37) or colonoscopy (reference). In our main analysis, the colonoscopy-only group had significantly higher odds of each outcome in the right side than the left; in comparison, the odds for FIT+ and mt-sDNA+ patients were more evenly distributed through the colon.

Conclusions: Our data suggest that FIT+ tests are associated with higher detection of both right- and left-sided AAs when compared to colonoscopy without a prior stool test. Furthermore, mt-sDNA+ patients had higher rates of left and right-sided AAs and ASPs, particularly on the right side.