Can the Sum of Adenoma Diameters (Adenoma Bulk) on Index Examination Predict Risk of Metachronous Advanced Neoplasia?

BACKGROUND:Recent data suggest that adenoma size and number are more important predictors of metachronous colorectal neoplasia than advanced histology. Furthermore, there is poor reproducibility in diagnosing advanced histology; high-grade dysplasia and villous histology. Therefore we developed a new metric, adenoma bulk, the sum of diameters of all baseline adenomas, regardless of advanced features. GOAL:Compare the predictive value for metachronous advanced neoplasia of adenoma bulk to conventional paradigm. STUDY:Data were collected prospectively in a multicenter adenoma-chemoprevention trial (2004 to 2013). For the conventional paradigm, high-risk baseline findings were defined as ≥3 adenomas, large adenomas (≥1 cm) or adenomas with villous components or high-grade dysplasia. Adenoma bulk was examined across quartiles and as a continuous variable. Predictive characteristics (sensitivities, specificities, c-statistics) for metachronous advanced neoplasia using conventional criteria and adenoma bulk were calculated. receiver operator characteristic curves were computed using logistic regression. RESULTS:In total, 1948 adults had index and follow-up colonoscopies (mean follow-up, 45.2 mo). Those with an adenoma bulk ≥10 mm (4th quartile) had a higher metachronous advanced neoplasia risk (14.4% vs. 6.9–8.2% in lower 3 quartiles; P=0.0002). The c-statistics and sensitivities (specificity fixed at 0.73) for the adenoma bulk and conventional models were 0.587 and 0.563 (P=0.17) and 0.396 and 0.390, respectively. CONCLUSIONS:Categorizing sporadic adenoma patients as high versus low risk for metachronous advanced neoplasia by adenoma bulk of