title: Phenotypic characteristics of hereditary non-polyposis colorectal cancer by the Amsterdam criteria: an Asian perspective.
abstract: BACKGROUND
  Hereditary non-polyposis colorectal cancer (HNPCC) is an autosomal disease with a 68-82% lifetime risk of colorectal cancer (CRC). This study examined the phenotypic characteristics of CRC in Amsterdam criteria-positive Asian patients from the Singapore Polyposis Registry.
  
  
  METHODS
  Hereditary non-polyposis CRC patients, defined by the Amsterdam I and II criteria, prospectively monitored in the Singapore Polyposis Registry over a 16-year period were reviewed. Clinical data were obtained from a computerized database and parameters, such as age of diagnosis, type and location of CRC, other associated cancers in the pedigree, cancer recurrence and survival were analysed.
  
  
  RESULTS
  Fifty-two patients (31 men and 21 women) from 42 unrelated families, with a median age of 44.5 years (range 27-73 years), fulfilled either Amsterdam I or II criteria and were included in our analysis. The racial distribution was 91% (n = 47) Chinese and 9% (n = 5) Malays, with a median follow up of 44.9 months (range 2-183 months). Significantly, 69% of tumours in this Amsterdam-defined cohort were left sided, with most being sigmoid cancers. Sixty per cent of all the tumours presented at a late stage (Dukes' C or D). Left-sided tumours presented with more advanced Dukes' stage (P = 0.096) and a higher rate of metastatic disease (P = 0.08) compared with right-sided lesions. There were, however, no significant differences in either disease-free or overall survival between right-sided and left-sided tumours.
  
  
  CONCLUSIONS
  This study emphasized the significant left-sided predominance of CRC in Amsterdam I and II-defined patients from our predominantly Chinese population, in contrast to those classically described in Lynch syndrome. Amsterdam criteria thus may not be suitable for diagnosing HNPCC in Asian populations and a greater emphasis should be made towards routine molecular diagnosis of mismatch repair gene defects in suspected HNPCC patients of Asian decent.
authors.affiliation: Department of Colorectal Surgery, Singapore General Hospital, Singapore.
authors.forename: Min-Hoe
authors.initials: MH
authors.lastname: Chew
authors.forename: Poh-Koon
authors.initials: PK
authors.lastname: Koh
authors.forename: Kheng-Hong
authors.initials: KH
authors.lastname: Ng
authors.forename: Jit-Fong
authors.initials: JF
authors.lastname: Lim
authors.forename: Kok-Sun
authors.initials: KS
authors.lastname: Ho
authors.forename: Boon-Swee
authors.initials: BS
authors.lastname: Ooi
authors.forename: Choong-Leong
authors.initials: CL
authors.lastname: Tang
authors.forename: Kong-Weng
authors.initials: KW
authors.lastname: Eu
mesh_terms: D000328:Adult; D000368:Aged; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000175:diagnosis / Q000208:ethnology* / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012846:Singapore / Q000453:epidemiology; D016019:Survival Analysis