The anatomic range of examination by fibreoptic rectosigmoidoscopy (60 centimetres)

The prevalence rate and anatomic location of colorectal adenoma and cancer detected by colonoscopy in average-risk individuals aged 40-80 years

BACKGROUND

The role of screening colonoscopy for colorectal (CR) neoplasia in average-risk population, remains to be determined.

OBJECTIVES

To evaluate the prevalence and anatomic location of CR adenoma and carcinoma and the morbidity of colonoscopy in individuals at average risk for CR cancer (CRC).

METHODS

A retrospective prevalence study of subjects aged 40-80 yr, with no cancer-related symptoms, personal or family history of CR neoplasia, who underwent a colonoscopy.

RESULTS

Enrolled were 1,177 persons; 183 aged 40-49 yr (young), 917 aged 50-75 yr, and 77 aged 76-80 yr (elderly). The prevalence of overall CR neoplasia, advanced neoplasia, and cancer was 20.9%, 6.3%, and 1.1%, respectively. In the 50-75 age group, the prevalence of overall adenoma, advanced neoplasia, and cancer was 21.3%, 6.7%, and 1.2%, respectively. Of the 206 neoplasia cases, 21-43% harbored proximal neoplasia beyond the reach of sigmoidoscopy, without distal lesions. Among the elderly, the prevalence of overall adenoma, advanced neoplasia, and cancer reached 26.0%, 14.3%, and 2.6%, respectively. In the young group, 9.8% had overall neoplasia, 1.1% had advanced adenoma, and none had CRC. Procedure-related morbidity rate was 0.1%, with no perforations, bleedings, or mortality.

CONCLUSIONS

Screening colonoscopy in average-risk subjects demonstrated a considerable prevalence of CR neoplasia and proximal lesions beyond the reach of sigmoidoscopy. The morbidity rate was negligible. Primary screening colonoscopy should be considered in health programs for the average-risk population, beginning at the age of 50 yr. The significantly high rate of advanced and proximal neoplasia in the elderly, encourages the inclusion of healthy subjects aged 76-80 yr in future prospective studies.

Incomplete screening flexible sigmoidoscopy associated with female sex, age, and increased risk of colorectal cancer

BACKGROUND

Several previous studies have found that females and older individuals are at greater risk of having incomplete flexible sigmoidoscopy. However, no prior study has reported the subsequent risk of colorectal cancer (CRC) following incomplete sigmoidoscopy.

METHODS

Using data from 55 791 individuals screened as part of the Colon Cancer Prevention (CoCaP) programme of Kaiser Permanente of Northern California, we evaluated the likelihood of having an inadequate (<40 cm) examination by age and sex, and estimated the risk of distal CRC according to depth of sigmoidoscope insertion at the baseline screening examination. Multivariate estimation of risks was performed using Poisson regression.

RESULTS

Older individuals were at a much greater risk of having an inadequate examination (relative risk (RR) for age 80+ years compared with 50-59 years 2.6 (95% confidence interval (CI) 2.3-3.0)), as were females (RR 2.3 (95% CI 2.2-2.5)); these associations were attenuated but remained strong if Poisson models were further adjusted for examination limitations (pain, stool, and angulation). There was an approximate threefold increase in the risk of distal CRC if the baseline sigmoidoscopy did not reach a depth of at least 40 cm; a smaller increase in risk was observed for examinations that reached 40-59 cm.

CONCLUSIONS

Older individuals and women are at an increased risk of having inadequate sigmoidoscopy. Because inadequate sigmoidoscopy results in an increased risk of subsequent CRC, physicians should consider steps to maximise the depth of insertion of the sigmoidoscope or, failing this, should consider an alternative screening test.

Association of older age and female sex with inadequate reach of screening flexible sigmoidoscopy

PURPOSE

Estimates of the sensitivity of screening sigmoidoscopy assume an adequate depth of insertion is reached. However, in clinical practice, the frequency that sigmoidoscopy reaches various lengths of the colon is not known. We assessed the frequency of inadequate reach (depth of <50 cm of the colon) in a large U.S. cohort, according to age and sex.

METHODS

We performed a cross-sectional study of 15,406 asymptomatic persons aged 50 years or older who underwent screening flexible sigmoidoscopy between April 1997 and October 2001 at sites participating in the Clinical Outcomes Research Initiative, which examines outcomes of endoscopy in "real life" settings. The maximum depth of insertion of the sigmoidoscope was measured in centimeters from the anus and classified as adequate (> or =50 cm) or inadequate (< 50 cm). Patient characteristics as well as procedure-related variables were also recorded.

RESULTS

Eighteen percent (n = 2801) of subjects had an inadequate examination. In men, the percentage of inadequate examinations increased progressively with age, from 10% (343/3338) in those aged 50 to 59 years to 22% (53/248) in those aged 80 years or older (P <0.001). Inadequate examinations were more common in women at all ages, ranging from 19% (733/3798) in those aged 50 to 59 years to 32% (86/267) in those aged 80 years or older (P <0.001). These associations were confirmed in a multivariable analysis.

CONCLUSION

Our finding that advancing age and female sex were independently associated with the risk of inadequate reach of screening sigmoidoscopy suggests that the sensitivity of sigmoidoscopy may be lower in these populations. Estimates of the benefits of sigmoidoscopy may need to be tailored to the age and sex of the patient.

Advanced distal colonic lesions as predictors of advanced lesions in the proximal colon

The characteristics of adenomas found during sigmoidoscopy have been suggested to predict synchronous adenomas in the proximal colon. Our aim was to examine whether the presence and characteristics of distal colonic lesions are associated with the presence and characteristics of lesions in the proximal colon. We performed a university hospital based case-control study with 3,268 consecutive subjects who received colonoscopy between January 1992 and December 1995. Subjects who had a history of colonic polyps, inflammatory bowel disease, intestinal resection, or had a contraindication against biopsies were excluded. Number size, and histologic characteristics of polyps in the distal and proximal colon were recorded. Advanced lesions were defined as neoplastic lesions with 1 or more of the following features: 1) > or = 1 cm diameter, and/or 2) villous histology, and/or 3) severe dysplasia or carcinoma, and/or 4) > or = 3 lesions. We found that 439 patients had neoplastic lesions in the distal colon only (61.3% with advanced lesions), 198 patients had lesions in the proximal colon only (55.1% advanced), and 197 had lesions in both the distal colon (74.6% advanced) and the proximal colon (55.8% advanced). Distal lesions were significantly more often advanced in patients with synchronous proximal lesions compared with patients with lesions in the distal colon only (odds ratio: 1.9; 95% confidence interval [CI]: 1.3-2.8; p < 0.001). The odds ratios for finding any neoplastic lesion in the proximal colon and an advanced proximal lesion, respectively, were 3.7 (2.6-5.3) (p < 0.001) and 2.2 (1.3-3.7) (p < 0.01) when a nonadvanced lesion was found in the distal colon, and 6.8 (5.3-8.7) (p < 0.001) and 6.7 (4.9-9.0) (p < 0.001) when an advanced lesion was found in the distal colon. Logistic regression analysis revealed number of distal polyps and villous histology as independent predictors of advanced lesions in the proximal colon; size and severe dysplasia were not independent predictors. In conclusion, characteristics of neoplastic lesions in the distal colon predict the presence and characteristics of lesions in the proximal colon.