title: The relationship between proximal and distal colonic adenomas: is screening sigmoidoscopy enough in the presence of a changing epidemiology?
abstract: OBJECTIVE
  Because the relationship between distal and proximal colonic findings remains uncertain, controversy exists over whether proctosigmoidoscopy or colonoscopy is more suitable for colorectal cancer (CRC) screening. We aim to describe the distribution and characteristics of polyps removed in colonoscopy screening.
  
  
  METHODS
  A prospective registry of a colonoscopy-based CRC screening program was developed on asymptomatic individuals over 50 years. All polyps were removed and characterized. Polyp size and histology were noted. Adenomas were considered advanced if they measured greater than 10 mm or were tubulovillous, villous, or malignant. The prevalence of advanced proximal polyps was determined and patients were categorized according to their family history of CRC.
  
  
  RESULTS
  A total of 696 individuals (418 women), aged 57.7 ± 10.3 years, were examined; 45.8% presented a colonic lesion, being adenomatous polyps in 32.7% individuals. Among these, 24.7% were advanced adenomas. Three patients (0.6%) presented invasive CRC. There were no significant differences with respect to sex and family history of CRC between patients with or without adenomas. Adenomas were more prevalent in individuals aged at least 65, irrespective of location (P<0.001). In 65.1% of individuals with adenomatous polyps in the right colon, there were no synchronous adenomas in the left colon (P<0.001). More adenomas were also present in the right colon of patients with no family history of CRC (P<0.001).
  
  
  CONCLUSIONS
  Most patients with adenomatous polyps in the right colon showed no synchronic adenomas on the left side. Lesions on the right side would have gone undetected if the individuals undergoing CRC screening had been explored with proctosigmoidoscopy.
authors.affiliation: Department of Gastroenterology, Tomelloso General Hospital, Tomelloso, Spain. alucendo@vodafone.es
authors.forename: Alfredo J
authors.initials: AJ
authors.lastname: Lucendo
authors.forename: Danila
authors.initials: D
authors.lastname: Guagnozzi
authors.forename: Teresa
authors.initials: T
authors.lastname: Angueira
authors.forename: Sonia
authors.initials: S
authors.lastname: González-Castillo
authors.forename: Mariluz
authors.initials: M
authors.lastname: Fernández-Fuente
authors.forename: Ana B
authors.initials: AB
authors.lastname: Friginal-Ruiz
authors.forename: Jose M
authors.initials: JM
authors.lastname: Tenias
mesh_terms: D000236:Adenoma / Q000453:epidemiology / Q000473:pathology*; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D002277:Carcinoma / Q000453:epidemiology / Q000473:pathology*; D016009:Chi-Square Distribution; D003111:Colonic Polyps / Q000453:epidemiology / Q000473:pathology*; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011237:Predictive Value of Tests; D015995:Prevalence; D011446:Prospective Studies; D012042:Registries; D012812:Sigmoidoscopy; D013030:Spain / Q000453:epidemiology