High-risk lesions are a stronger predictor for interval cancer than adenoma detection rate

Background:

After index colonoscopy patients with high-risk adenomas (≥2 polyps or ≥10 mm or high grade dysplasia or villous or tubulovillous histology) should undergo surveillance colonoscopy after 3 years, patients with low-risk adenomas after 10 years. Although endoscopic screening reached high quality standards, interval cancers still occur in a significant number of patients and the underlying risk factors are poorly understood.

Aims: To evaluate if patients with high-risk adenomas are at increased risk for interval cancers.

Methods:

Screening colonoscopies performed between 1/2009 and 6/2015 within the “Qualitätszertifikat Darmkrebsvorsorge” were included. An interval cancer was defined as colorectal cancer diagnosed at least 6 month after screening colonoscopy and the scheduled time of surveillance colonoscopy.

Results:

146,894 colonoscopies were included (50.8% women, median age 60 years) of which 19% were classified as high-risk. During a median follow up of 36.9 month, 114 interval cancers were identified. Patients with high-risk lesions had significantly higher incidence rates of interval cancers than those in the low risk group (HR 1.77 [1.18 – 2.66]; p = 0.006). Other factors associated with interval cancer were older age (HR per 10 years 1.87 [1.52 – 2.29]; p < 0.001) and adenoma detection rate ≤20% (HR 0.65 [0.44 – 0.95]; p = 0.025). Interestingly, there was no association with female sex.

Conclusion:

High-risk lesions are a stronger predictor for the occurrence of interval cancer than poor adenoma detection rate. In contrast to previous studies there was no association with female sex.