title: Increased risk of advanced neoplasms among asymptomatic siblings of patients with colorectal cancer.
abstract: OBJECTIVE
  Colorectal cancer (CRC) is the second-most common cancer in Hong Kong. Relatives of patients with CRC have an increased risk of colorectal neoplasm. We assessed the prevalence of advanced neoplasms among asymptomatic siblings of patients with CRC.
  
  
  METHODS
  Patients with CRC were identified from the Prince of Wales Hospital CRC Surgery Registry from 2001 to 2011. Colonoscopies were performed for 374 siblings of patients (age, 52.6 ± 7.4 y) and 374 age- and sex-matched siblings of healthy subjects who had normal colonoscopies and did not have a family history of CRC (controls, 52.7 ± 7.4 y). We identified individuals with advanced neoplasms (defined as cancers or adenomas of at least 10 mm in diameter, high-grade dysplasia, with villous or tubulovillous characteristics).
  
  
  RESULTS
  The prevalence of advanced neoplasms was 7.5% among siblings of patients and 2.9% among controls (matched odds ratio [mOR], 3.07; 95% confidence interval [CI], 1.5-6.3; P = .002). The prevalence of adenomas larger than 10 mm was higher among siblings of patients than in controls (5.9% vs 2.1%; mOR, 3.34; 95% CI, 1.45-7.66; P = .004), as was the presence of colorectal adenomas (31.0% vs 18.2%; mOR, 2.19; 95% CI, 1.52-3.17; P < .001). Six cancers were detected among siblings of patients; no cancers were detected in controls. The prevalence of advanced neoplasms among siblings of patients was higher when their index case was female (mOR, 4.95; 95% CI, 1.81-13.55) and had distally located CRC (mOR, 3.10; 95% CI, 1.34-7.14).
  
  
  CONCLUSIONS
  In Hong Kong, siblings of patients with CRC have a higher prevalence of advanced neoplasms, including CRC, than siblings of healthy individuals. Screening is indicated in this high-risk population. ClinicalTrials.gov number: NCT00164944.
authors.affiliation: Department of Medicine and Therapeutics, Institute of Digestive Disease, Li Ka Shing Institute of Health Sciences, Prince of Wales Hospital, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China.
authors.forename: Siew C
authors.initials: SC
authors.lastname: Ng
authors.forename: James Y W
authors.initials: JY
authors.lastname: Lau
authors.forename: Francis K L
authors.initials: FK
authors.lastname: Chan
authors.forename: Bing Yee
authors.initials: BY
authors.lastname: Suen
authors.forename: Wai-Keung
authors.initials: WK
authors.lastname: Leung
authors.forename: Yee Kit
authors.initials: YK
authors.lastname: Tse
authors.forename: Simon S M
authors.initials: SS
authors.lastname: Ng
authors.forename: Janet F Y
authors.initials: JF
authors.lastname: Lee
authors.forename: Ka-Fai
authors.initials: KF
authors.lastname: To
authors.forename: Justin C Y
authors.initials: JC
authors.lastname: Wu
authors.forename: Joseph J Y
authors.initials: JJ
authors.lastname: Sung
mesh_terms: D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000473:pathology*; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D012306:Risk; D035781:Siblings