Development and validation of the WASP classification system for optical diagnosis of adenomas, hyperplastic polyps and sessile serrated adenomas/polyps.
Accurate endoscopic differentiation would enable to resect and discard small and diminutive colonic lesions, thereby increasing cost-efficiency. Current classification systems based on narrow band imaging (NBI), however, do not include neoplastic sessile serrated adenomas/polyps (SSA/Ps). We aimed to develop and validate a new classification system for endoscopic differentiation of adenomas, hyperplastic polyps and SSA/Ps <10 mm.



We developed the Workgroup serrAted polypS and Polyposis (WASP) classification, combining the NBI International Colorectal Endoscopic classification and criteria for differentiation of SSA/Ps in a stepwise approach. Ten consultant gastroenterologists predicted polyp histology, including levels of confidence, based on the endoscopic aspect of 45 polyps, before and after participation in training in the WASP classification. After 6 months, the same endoscopists predicted polyp histology of a new set of 50 polyps, with a ratio of lesions comparable to daily practice.



The accuracy of optical diagnosis was 0.63 (95% CI 0.54 to 0.71) at baseline, which improved to 0.79 (95% CI 0.72 to 0.86, p<0.001) after training. For polyps diagnosed with high confidence the accuracy was 0.73 (95% CI 0.64 to 0.82), which improved to 0.87 (95% CI 0.80 to 0.95, p<0.01). The accuracy of optical diagnosis after 6 months was 0.76 (95% CI 0.72 to 0.80), increasing to 0.84 (95% CI 0.81 to 0.88) considering high confidence diagnosis. The combined negative predictive value with high confidence of diminutive neoplastic lesions (adenomas and SSA/Ps together) was 0.91 (95% CI 0.83 to 0.96).



We developed and validated the first integrative classification method for endoscopic differentiation of small and diminutive adenomas, hyperplastic polyps and SSA/Ps. In a still image evaluation setting, introduction of the WASP classification significantly improved the accuracy of optical diagnosis overall as well as SSA/P in particular, which proved to be sustainable after 6 months.
Department of Gastroenterology and Hepatology, Academic Medical Center, Amsterdam, The Netherlands.
Joep E G
JE
IJspeert
Department of Gastroenterology and Hepatology, Academic Medical Center, Amsterdam, The Netherlands.
Barbara A J
BA
Bastiaansen
Department of Gastroenterology and Hepatology, Netherlands Cancer Institute, Amsterdam, The Netherlands.
Monique E
ME
van Leerdam
Department of Pathology, Vrije Universiteit Medical Center, Amsterdam, The Netherlands.
Gerrit A
GA
Meijer
Department of Pathology, Academic Medical Center, Amsterdam, The Netherlands.
Susanne
S
van Eeden
Division of Gastroenterology and Hepatology, Maastricht University Medical Center, Maastricht, The Netherlands.
Silvia
S
Sanduleanu
Department of Gastroenterology and Hepatology, Catharina Hospital, Eindhoven, The Netherlands.
Erik J
EJ
Schoon
Department of Gastroenterology and Hepatology, Radboud University Medical Centre, Nijmegen, The Netherlands.
Tanya M
TM
Bisseling
Department of Gastroenterology and Hepatology, Erasmus University Medical Centre, Rotterdam, The Netherlands.
Manon Cw
MC
Spaander
Department of Gastroenterology and Hepatology, St. Antonius Hospital, Nieuwegein, The Netherlands.
Niels
N
van Lelyveld
Department of Gastroenterology and Hepatology, Medical Spectrum Twente, Enschede, The Netherlands.
Marloes
M
Bargeman
Department of Clinical Epidemiology, Biostatistics & Bioinformatics, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
Junfeng
J
Wang
Department of Gastroenterology and Hepatology, Academic Medical Center, Amsterdam, The Netherlands.
Evelien
E
Dekker
D000236:Adenoma / Q000145:classification / Q000175:diagnosis*; D003111:Colonic Polyps / Q000175:diagnosis*; D003113:Colonoscopy / Q000379:methods; D015179:Colorectal Neoplasms / Q000145:classification / Q000175:diagnosis*; D006801:Humans; D062048:Narrow Band Imaging / Q000379:methods; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
CANCER PREVENTION; COLONIC POLYPS; COLONOSCOPY; COLORECTAL CANCER; COLORECTAL NEOPLASM