title: Metachronous colorectal cancer risk in patients with a moderate family history.
abstract: OBJECTIVE
  Lifetime risk of a metachronous colorectal cancer (mCRC) is 0.6-3% following sporadic colorectal cancer (CRC) and 15-26% in Lynch syndrome. The lifetime incidence of CRC in individuals with moderate familial risk is 8-17%. Risk of mCRC is unknown.
  
  
  METHODS
  A retrospective longitudinal study of the Regional Familial CRC Registry was performed. Patients who had at least one CRC were categorized as follows: moderate risk (n = 383), Lynch syndrome (n = 528) and average (population) risk (n = 409). The Kaplan-Meier estimate (1-KM) and the cumulative incidence function were used to calculate the risk of mCRC. The 1-KM gives the risk for individuals remaining at risk (alive) at a given time point and thus is useful for counselling. The cumulative incidence function gives the risk for the whole population.
  
  
  RESULTS
  The 1-KM and the cumulative incidence function demonstrated that the risk of mCRC was significantly higher in moderate-risk patients compared with average (population)-risk patients (1-KM, P = 0.008; cumulative incidence function, P = 0.00097). However, the risk of mCRC was higher in patients with Lynch syndrome than in moderate-risk or average (population)-risk patients. The 1-KM in moderate-risk patients was 2.7%, 6.3% and 23.5% at 5, 10 and 20 years, respectively. In average (population)-risk patients, the 1-KM was 1.3%, 3.1% and 7.0% at 5, 10 and 20 years, and the cumulative incidence function was 0.3%, 0.6% and 2.4% at the same time points, respectively.
  
  
  CONCLUSIONS
  These data indicate that the risk of mCRC is significantly higher in patients with a moderate family history of CRC than in those with an average (population) risk. This justifies proactive lifelong surveillance.
authors.affiliation: Department of General Surgery, Manchester Royal Infirmary, Central Manchester University Hospitals Foundation Trust, Manchester, UK. katynewton2002@yahoo.co.uk
authors.forename: K F
authors.initials: KF
authors.lastname: Newton
authors.forename: K
authors.initials: K
authors.lastname: Green
authors.forename: S
authors.initials: S
authors.lastname: Walsh
authors.forename: F
authors.initials: F
authors.lastname: Lalloo
authors.forename: J
authors.initials: J
authors.lastname: Hill
authors.forename: D G R
authors.initials: DG
authors.lastname: Evans
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics*; D005260:Female; D005500:Follow-Up Studies; D020022:Genetic Predisposition to Disease; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D006113:United Kingdom / Q000453:epidemiology