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Likelihood of missed and recurrent adenomas in the proximal versus the distal colon
Adeyinka O Laiyemo1, Chyke Doubeni, Andrew K Sanderson
1Department of Medicine, Howard University College of Medicine, Washington, DC, USA. adeyinka.laiyemo@howard.edu
Background:
Colonoscopy may be less efficacious in reducing colorectal cancer mortality in the proximal compared with the distal colon. A greater likelihood for missed and recurrent adenomas in the proximal colon may contribute to this phenomenon.
Objective:
To examine whether a proximal adenoma is associated with the risk and location of missed and recurrent adenomas.
Design:
Prospective.
Setting:
Polyp Prevention Trial.
Participants:
A total of 1864 patients with an adenoma at baseline underwent a follow-up colonoscopy 4 years later (adenoma recurrence). Of these, 1731 underwent a clearing colonoscopy 1 year after the baseline examination (missed adenoma).
Main Outcome Measurements:
Association of baseline adenoma location with the risk and location of adenomas found at colonoscopy performed 1 year and 4 years later.
Results:
At the year 1 colonoscopy, 598 patients (34.6%) had an adenoma (missed adenoma). Compared with those with a distal-only adenoma at baseline, patients with a proximal-only adenoma at baseline were more likely to have any missed adenomas (relative risk [RR] 1.28; 95% CI, 1.09-1.49) and a proximal-only missed adenoma (RR 2.05; 95% CI, 1.49-2.80). At the year 4 colonoscopy, 733 patients (39.3%) had adenoma recurrence. Patients with a baseline proximal-only adenoma were more likely to have any adenoma recurrence (RR 1.14; 95% CI, 1.00-1.31) and a proximal-only adenoma recurrence (RR 1.52; 95% CI, 1.15-2.02). Sensitivity analyses involving missed adenomas did not materially affect the risk or location of recurrent adenomas at year 4 colonoscopy.
Limitation:
Lesions may still be missed on repeated colonoscopies.
Conclusions:
Missed and recurrent adenomas are more likely to be in the proximal colon.
