title: Nonpolypoid colorectal neoplasms: gender differences in prevalence and malignant potential.
abstract: OBJECTIVE
  Colonoscopy may fail to prevent colorectal cancer, especially in the proximal colon and in women. Nonpolypoid colorectal neoplasms may potentially explain some of these post-colonoscopy cancers. In the present study, we aimed to examine the prevalence and malignant potential of nonpolypoid colorectal neoplasms in a large population, with special attention to gender and location.
  
  
  METHODS
  We performed a cross-sectional study of all consecutive patients undergoing elective colonoscopy at a single academic medical center. The endoscopists were familiarized on the detection and treatment of nonpolypoid lesions. Advanced histology was defined by the presence of high-grade dysplasia or early cancer.
  
  
  RESULTS
  We included 2310 patients (53.9% women, mean age 58.4 years) with 2143 colorectal polyps. Prevalences of colorectal neoplasms and nonpolypoid colorectal neoplasms were lower in women than in men (20.9% vs. 33.7%, p < 0.001 and 3.0% vs. 5.5%, p = 0.002). In women, nonpolypoid colorectal neoplasms were significantly more likely to contain advanced histology than polypoid ones (OR 2.89, 95% CI 1.24-6.74, p = 0.01), while this was not the case in men (OR 0.91, 95% CI 0.40-2.06, p = 0.83). Proximal neoplasms with advanced histology were more likely to be nonpolypoid than distal ones (OR 4.68, 95% CI 1.54-14.2, p = 0.006).
  
  
  CONCLUSIONS
  Nonpolypoid mechanisms may play an important role in colorectal carcinogenesis, in both women and men. Although women have fewer colorectal neoplasms than men, they have nonpolypoid colorectal neoplasms, which frequently contain advanced histology.
authors.affiliation: Department of Internal Medicine, Division of Gastroenterology and Hepatology, Maastricht University Medical Center, Netherlands.
authors.forename: Eveline J A
authors.initials: EJ
authors.lastname: Rondagh
authors.forename: Ad A M
authors.initials: AA
authors.lastname: Masclee
authors.forename: Mirthe E
authors.initials: ME
authors.lastname: van der Valk
authors.forename: Bjorn
authors.initials: B
authors.lastname: Winkens
authors.forename: Adriaan P
authors.initials: AP
authors.lastname: de Bruïne
authors.forename: Tonya
authors.initials: T
authors.lastname: Kaltenbach
authors.forename: Roy M
authors.initials: RM
authors.lastname: Soetikno
authors.forename: Silvia
authors.initials: S
authors.lastname: Sanduleanu
mesh_terms: D000236:Adenoma / Q000175:diagnosis / Q000453:epidemiology* / Q000473:pathology*; D016009:Chi-Square Distribution; D003111:Colonic Polyps / Q000453:epidemiology / Q000473:pathology; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000453:epidemiology* / Q000473:pathology*; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D055088:Early Detection of Cancer; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D016017:Odds Ratio; D015995:Prevalence; D012737:Sex Factors