title: Colorectal polyp counts and cancer risk in familial adenomatous polyposis.
abstract: OBJECTIVE
  In familial adenomatous polyposis, colorectal cancer prevention is by prophylactic colectomy, but dietary or chemopreventative strategies have been recently proposed in low-risk individuals. The aim of this study was to define predictive risk factors for colorectal cancer in familial adenomatous polyposis.
  
  
  METHODS
  Between 1918 and 1993, 317 patients underwent colectomy. A multivariate analysis was performed to assess the relationship between colorectal cancer risk and polyp count, sex, and age at colectomy.
  
  
  RESULTS
  The median polyp count was 842 (range, 78-7500), and cancer was found in 22% of patients. Polyp count and age, but not sex, predicted cancer risk. Patients with >1000 polyps had 2.3 times greater risk of cancer than those with <1000 polyps (P=0.006). Synchronous cancers increased with poly count (P<0.05). Each 10-year age group had a 2.4-fold difference in cancer risk (95% confidence interval, 1.9-3.2; P<0.001). Four cases of cancer occurred in patients at low risk (younger than 30 years of age, <1000 polyps; 3.3%).
  
  
  CONCLUSIONS
  More adenomas and older age are associated with a higher risk of colorectal cancer. However, cancer does occur in low-risk individuals and may be missed by surveillance, making alternatives to prophylactic surgery inadvisable.
authors.affiliation: Colorectal Unit, St. Mark's Hospital, London, England.
authors.forename: H S
authors.initials: HS
authors.lastname: Debinski
authors.forename: S
authors.initials: S
authors.lastname: Love
authors.forename: A D
authors.initials: AD
authors.lastname: Spigelman
authors.forename: R K
authors.initials: RK
authors.lastname: Phillips
mesh_terms: D011125:Adenomatous Polyposis Coli / Q000473:pathology* / Q000601:surgery; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002648:Child; D003082:Colectomy; D003106:Colon / Q000473:pathology*; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011336:Probability; D012007:Rectum / Q000473:pathology*; D012307:Risk Factors