; * The SMAC Workgroup is reported in the Appendix. A Multicenter Study of Colorectal Adenomas Rationale, Objectives, Methods and Characteristics of the Study Cohort

Do patients with rectosigmoid adenomas 5 mm or less in diameter need total colonoscopy?

BACKGROUND

The need for colonoscopy in the care of patients with rectosigmoid adenoma 5 mm or less in diameter is still debatable.

METHODS

We estimated the prevalence of proximal adenomas among 3052 consecutive subjects undergoing total colonoscopy. Rectosigmoid adenoma was classified as diminutive (5 mm), small (6 to 10 mm), or large (>/=11 mm). Advanced proximal adenoma was 10 mm in diameter or larger, or with a villous component, severe dysplasia, or infiltrating adenocarcinoma.

RESULTS

Proximal adenoma was found in 212 of 2483 patients (8.5%, 95% CI [7.5, 9.7]) without distal neoplastic polyps, 49 of 214 (22.9%, 95% CI [17.6, 29.2]) with diminutive, 44 of 174 (25.3%, 95% CI [19.1, 32.5] with small, and 70 of 181 (38.7%, 95% CI [31.6, 46.2]) with large distal adenoma. Advanced proximal adenoma was found in 49 (2.0%, 95% CI [1.5, 2.6]), 8 (3.7%, 95% CI [1.7, 7.5]), 17 (9.8%, 95% CI [6.0, 15.4]), and 29 patients (16.0%, 95% [11.2, 22.4]), respectively. In patients with distal adenoma risk for proximal lesions increased with increasing age, size, and number of distal adenomas (p = 0.01). Size of distal adenoma was the strongest predictor of the presence of proximal advanced adenoma (multivariate analyses).

CONCLUSIONS

In a clinical setting, the decision to perform colonoscopy should take into account proximal lesions of clinical interest, life expectancy, costs, and risks associated with the procedure. When detection of advanced proximal adenoma is the goal, presence of distal diminutive adenoma alone might not be an indication for total colonoscopy.

Distal hyperplastic polyps do not predict proximal adenomas: results from a multicentric study of colorectal adenomas

BACKGROUND

The association between distal hyperplastic polyps and proximal adenomas is still a matter of debate. We investigated this association while taking into account patient characteristics.

METHODS

After exclusion of patients with inflammatory bowel diseases, familial adenomatous polyposis, or any cancer, 3088 eligible consecutive subjects aged 18 to 69 years underwent total colonoscopy in four gastroenterology units. The odds ratios (OR) of having proximal adenomas according to patient characteristics (age, sex, medical center, year of endoscopy, reasons for referral, and distal findings) were estimated in univariate and multivariate analyses.

RESULTS

Patients with distal polyps of any type showed an adjusted OR of 2.5 (95% CI [1.9, 3.1] p < .001) of having proximal adenomas as compared with those without distal polyps. When distal adenomas and distal hyperplastic polyps were included in the multivariate model as independent factors, the presence of adenomas significantly increased the risk of proximal adenomas (OR = 2.8: 95% CI [2.2, 3.6] p < .001), whereas the presence of hyperplastic polyps did not (OR = 1.1: 95% CI [0.8, 1.5] p = .64). No association with number, size, or location of distal hyperplastic polyps was seen.

CONCLUSIONS

Our data show that the presence of hyperplastic polyps should not be the sole indication for total colonoscopy because they are not associated with proximal adenomas when adjusting for patient characteristics and presence of distal adenomas.