Concerns and challenges in flexible sigmoidoscopy screening

The impact of endoscopist performance and patient factors on distal adenoma detection and colorectal cancer incidence

BACKGROUND

High quality endoscopy is key for detecting and removing precursor lesions to colorectal cancer (CRC). Adenoma detection rates (ADRs) measure endoscopist performance. Improving other components of examinations could increase adenoma detection.

AIMS

To investigate how endoscopist performance at flexible sigmoidoscopy (FS) affects adenoma detection and CRC incidence.

METHODS

Among 34,139 participants receiving FS screening by the main endoscopist at one of 13 centres in the UK FS Screening Trial, median follow-up was 17 years. Factors examined included family history of CRC, bowel preparation quality, insertion and withdrawal time, bowel segment reached, patient pain and ADR. Odds ratios (OR) for distal adenoma detection were estimated by logistic regression. Hazard ratios (HR) for distal CRC incidence were estimated by Cox regression.

RESULTS

At screening, 4,104 participants had distal adenomas detected and 168 participants developed distal CRC during follow-up. In multivariable models, a family history of CRC (yes vs. no: OR 1.40, 95%CI 1.21-1.62), good or adequate bowel preparation quality (vs. excellent: OR 0.84, 95%CI 0.74-0.95; OR 0.56, 95%CI 0.49-0.65, respectively) and longer insertion and withdrawal times (≥ 4.00 vs. < 2.00 min: OR 1.96, 95%CI 1.68-2.29; OR 32.79, 95%CI 28.22-38.11, respectively) were associated with adenoma detection. Being screened by endoscopists with low or intermediate ADRs, compared to high ADRs, was positively associated with CRC incidence (multivariable: HR 4.71, 95%CI 2.65-8.38; HR 2.16, 95%CI 1.22-3.81, respectively).

CONCLUSIONS

Bowel preparation quality and longer insertion and withdrawal time are key for improving distal adenoma detection. Higher ADRs were associated with a lower risk of distal CRC.

Development and Validation of the Asia-Pacific Proximal Colon Neoplasia Risk Score

BACKGROUND & AIMS

Patients found to be at high risk of advanced proximal neoplasia (APN) after flexible sigmoidoscopy screening should be considered for colonoscopy examination. We developed and validated a scoring system to identify persons at risk for APN.

METHODS

We collected data from 7954 asymptomatic subjects (age, 50-75 y) who received screening colonoscopy examinations at 14 sites in Asia. We randomly assigned 5303 subjects to the derivation cohort and the remaining 2651 to the validation cohort. We collected data from the derivation cohort on age, sex, family history of colorectal cancer, smoking, drinking, body mass index, medical conditions, and use of nonsteroidal anti-inflammatory drugs or aspirin. Associations between the colonoscopic findings of APN and each risk factor were examined using the Pearson χ² test, and we assigned each participant a risk score (0-15), with scores of 0 to 3 as average risk and scores of 4 or higher as high risk. The scoring system was tested in the validation cohort. We used the Cochran-Armitage test of trend to compare the prevalence of APN among subjects in each group.

RESULTS

In the validation cohort, 79.5% of patients were classified as average risk and 20.5% were classified as high risk. The prevalence of APN in the average-risk group was 1.9% and in the high-risk group was 9.4% (adjusted relative risk, 5.08; 95% CI, 3.38-7.62; P < .001). The score included age (61-70 y, 3; ≥70 y, 4), smoking habits (current/past, 2), family history of colorectal cancer (present in a first-degree relative, 2), and the presence of neoplasia in the distal colorectum (nonadvanced adenoma 5-9 mm, 2; advanced neoplasia, 7). The c-statistic of the score was 0.74 (95% CI, 0.68-0.79), and for distal findings alone was 0.67 (95% CI, 0.60-0.74). The Hosmer-Lemeshow goodness-of-fit test statistic was greater than 0.05, indicating the reliability of the validation set. The number needed to refer was 11 (95% CI, 10-13), and the number needed to screen was 15 (95% CI, 12-17).

CONCLUSIONS

We developed and validated a scoring system to identify persons at risk for APN. Screening participants who undergo flexible sigmoidoscopy screening with a score of 4 points or higher should undergo colonoscopy evaluation.

Economic evaluation of colorectal cancer screening programs: Affordability for the health service

OBJECTIVES

To estimate the cost-effectiveness of the public colorectal cancer screening program in the Abruzzo region, Italy.

METHODS

Cost-effectiveness was analysed using a two-armed Markov model comparing: (1) Abruzzo screening program based on biennial faecal immunochemical occult blood testing, with colonoscopy as second level test for individuals with positive results, with (2) Treatment of symptomatic patients according to the stage of the neoplasm. Transition probabilities were adjusted for accuracy of tests and incidence of colorectal cancer. Diagnosis-related groups' charges and field collected data were used to estimate costs. Costs and benefits were discounted by 3.5%. Monte Carlo simulation confirmed the robustness of the model results.

RESULTS

Assuming a compliance rate of 64.7%, the incremental cost-effectiveness ratio for the current colorectal screening program was €433.06/quality adjusted life year gained, considerably lower than conventional thresholds (around €30,000).

CONCLUSION

Early detection and intervention programs help to avoid a large number of highly debilitating and expensive cancer treatments. These results show that the screening program currently implemented in Abruzzo should be considered as a good investment in health.

The impact of screening on cancer incidence and mortality in Missouri, USA, 2004-2013

OBJECTIVES

Population-based evidence regarding impact of cancer screenings and cancer rates in Missouri is lacking. This study examined whether screenings of breast cancer, cervical cancer, and colorectal cancer impact early-stage cancer incidence and mortality in Missouri.

STUDY DESIGN

This is an ecological study based on county-specific estimates of selected cancer screening prevalence and early-stage cancer incidence and cancer mortality.

METHODS

County-specific prevalence of clinical breast examination, mammography, Pap test, sigmoidoscopy or colonoscopy, and fecal occult blood test (FOBT) were generated from Missouri County-Level Study (2003, 2007, and 2011). County-specific crude incidence and mortality were calculated (2004-2013). Pearson's correlation and Poisson regression were used to test association between cancer rate and screening prevalence. Covariates included county-level mean age, percentage of whites, percentage with low income, percentage with less than high school education high school, percentage with no insurance, and percentage having difficulties accessing care.

RESULTS

In the adjusted model, 'ever had Pap test' was significantly associated with an increase of 8% in early-stage cervical cancer incidence. Having clinical breast examination or Pap test in the past was also associated with decreases in mortality by 3% and 4%, respectively, although the association was not significant for Pap test. In addition, having mammography was statistically significantly associated with early-stage breast cancer incidence, and having FOBT or sigmoidoscopy or colonoscopy was associated with decreased colorectal cancer mortality; however, magnitude for these associations was only around 1%.

CONCLUSIONS

This study provides ecological evidence of the effectiveness of screening services in predicting early stage cancer incidence and in reducing mortality across Missouri counties. Further incentive to promote these screenings in Missouri is needed.