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Original research
Prospective colonoscopic study to investigate risk of colorectal neoplasms in first-degree relatives of patients with non-advanced adenomas
  1. Siew C Ng1,2,3,4,
  2. Moe Htet Kyaw2,
  3. Bing Yee Suen2,
  4. Yee Kit Tse2,
  5. Martin C S Wong2,
  6. Aric J Hui5,
  7. Hui Yee Tak6,
  8. James Y W Lau2,7,
  9. Joseph J Y Sung2,4,
  10. Francis K L Chan1,2
  1. 1 Department Medicine and Therapeutics, The Chinese University of Hong Kong, Shatin, China
  2. 2 Institute of Digestive Diseases, The Chinese University of Hong Kong, Shatin, China
  3. 3 Li Ka Shing health sciences research institute, The Chinese University of Hong Kong, Hong Kong, China
  4. 4 State Key Laboratory of digestive disease, Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Shatin, China
  5. 5 Department of Medicine, Alice Ho Miu Ling Nethersole Hospital, Hong Kong, China
  6. 6 Department of Medicine, Queen Elizabeth Hospital, Hong Kong, China
  7. 7 Department of Surgery, The Chinese University of Hong Kong, Shatin, China
  1. Correspondence to Professor Siew C Ng, Department of Medicine and Therapeutics, Institute of digestive disease, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Science, The Chinese University of Hong Kong, Hong Kong; siewchienng{at}


Objective The risk associated with a family history of non-advanced adenoma (non-AA) is unknown. We determined the prevalence of colorectal neoplasms in subjects who have a first-degree relative (FDR) with non-AA compared with subjects who do not have an FDR with adenomas.

Design In a blinded, cross-sectional study, consecutive subjects with newly diagnosed non-AA were identified from our colonoscopy database. 414 FDRs of subjects with non-AA (known as exposed FDRs; mean age 55.0±8.1 years) and 414 age and sex-matched FDRs of subjects with normal findings from colonoscopy (known as unexposed FDRs; mean age 55.2±7.8 years) underwent a colonoscopy from November 2015 to June 2018. One FDR per family was recruited. FDRs with a family history of colorectal cancer were excluded. The primary outcome was prevalence of advanced adenoma (AA). Secondary outcomes included prevalence of all adenomas and cancer.

Results The prevalence of AA was 3.9% in exposed FDRs and 2.4% in unexposed FDRs (matched OR (mOR)=1.67; 95% CI 0.72 to 3.91; p=0.238 adjusted for proband sex and proband age). Exposed FDRs had a higher prevalence of any adenomas (29.2% vs 18.6%; mOR=1.87; 95% CI 1.32 to 2.66; p<0.001) and non-AA (25.4% vs 16.2%; mOR=1.91; 95% CI 1.32 to 2.76; p=0.001). A higher proportion of exposed FDRs than unexposed FDRs (4.3% vs 2.2%; adjusted mOR=2.44; 95% CI 1.01 to 5.86; p=0.047) had multiple adenomas. No cancer was detected in both groups.

Conclusion A positive family history of non-AA does not significantly increase the risk of clinically important colorectal neoplasia. The data support current guidelines which do not advocate earlier screening in individuals with a family history of non-AA.

Trial registration number NCT0252172.

  • colorectal adenomas
  • family cancer
  • colonoscopy

Statistics from


  • Contributors SCN designed and supervised the study. JYWL, AJH and FKLC provided critical input to study design. MHK and SCN performed the colonoscopy procedures and drafted the manuscript. BYS recruited and followed up patients, and collected clinical data. Data analysis was done by BYS and YKT. The manuscript was critically reviewed by SCN, AJH, JYWL, JJYS and FKLC, without editorial support. All authors read, revised and approved the final report.

  • Funding This study was supported by Health and Medical Research Fund (HMRF) in Hong Kong.

  • Disclaimer The funder of the study had no role in study design, data collection, data analysis, data interpretation or writing of the report.

  • Competing interests SCN has served as a consultant to Takeda, Janssen, AbbVie and Ferring. She had been paid lecture fees by Takeda, Janssen, AbbVie, Ferring and Menarini. FKLC has served as a consultant to Eisai, Pfizer, Takeda and Otsuka. He has been paid lecture fees by Eisai, Pfizer, AstraZeneca and Takeda. All other authors have nothing to declare.

  • Ethics approval Clinical Research Ethics Committee of The Chinese University of Hong Kong and New Territories East Cluster of Hospital Authority (Ethical approval number 2015.145; number NCT02521727)

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Presented at These data were previously presented at Digestive Disease Week 2017, Chicago.

  • Patient consent for publication Not required.

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