Clinical summary

Abstract

Aim

To evaluate the association between ADR and the risks of CRC diagnosed 6 months-10 years after colonoscopy (interval cancer) and of cancer-related death.

Study design

Multicenter, retrospective review of community-based patients undergoing colonoscopy, ≥50 years old, and had at least 6 months of subsequent follow-up. Gastroenterologists (GI) included a large group of endoscopists in a community-based setting who had completed at least 300 or more total colonoscopic examinations and 75 or more screening examinations during the study period. Patients were followed from colonoscopy to the first of the following events:

• Completion of 10-year follow-up
• Diagnosis of CRC
• Discontinuation of membership of the GI practice or end of study period

Key findings

136 community-based gastroenterologists had more than 300 total examinations/75 screening examinations in the study period and were included in the sampling. 223,842 patients were included, with a total of 264,972 colonoscopies with at least 6 months of follow up data:

• Median patient age 64 years (IQR 57-72)
• Majority of colonoscopies performed were diagnostic (57.4%)
• 927,523 person-year of follow-ups
• 712 interval colorectal adenocarcinomas (7.7/10,000 person-year risk of interval cancer)

Adenoma detection rates ranged from 7.4-52.5%:

• Physicians in the highest ADR quintile (33.51-52.51%) resulted in patients with a 4.8/10,000 person-year risk of interval cancer.

Physicians in the lowest ADR (7.35-19.05%) quintile resulted in patients with a 7.7/10,000 person-year risk of interval cancer:

• Patients risk for CRC whose physicians had the lowest ADR (7.35-19.05%) was 9.8 cases per 10,000 person-yrs.
• Patients with physicians in the highest ADR quintile (compared to lowest quintile) reduced their risk of advanced-stage cancer/fatal cancer by 57%/62%.

Analysis suggested that physicians who increased their ADR from <19% to 34-53% might prevent 1 additional interval cancer over 10 years for every 213 colonoscopies performed: 

• The risk of interval cancer decreased linearly with increased ADR.
• Each 1% increase in ADR predicted a 3% decrease in risk of interval cancer.
• Each 1% increase in ADR was associated with a 5% decrease in risk of a fatal interval cancer.
• Observed in both men and women patients, in all areas of the colon. 

Patients with physicians in the highest ADR quintile (compared to lowest quintile) reduced their risk of advanced-stage cancer/fatal cancer by 57%/62%.

• 712 interval colorectal adenocarcinomas, of which 255 were advanced stage cancers, and 147 deaths detected during a 10-year follow-up period (37.5% of CRCs diagnosed were in the distal colon, 60% were in the proximal colon. 2.5% were unknown location).
• 48% risk reduction of CRC for patients whose physicians had the highest ADR as compared to patients whose physicians had the lowest ADR (57% risk reduction for women, 40% risk reduction for men).

Each 1% increase in ADR predicted a 3% decrease in risk of interval cancer. 

Each 1% increase in ADR was associated with a 5% decrease in risk of a fatal interval cancer.

Conclusion

Adenoma detection rates are inversely proportionate to the risk of interval colorectal cancers, advanced stage colorectal, and fatal colorectal cancers.