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Original article
Detection of miR-92a and miR-21 in stool samples as potential screening biomarkers for colorectal cancer and polyps
  1. Chung Wah Wu1,
  2. Simon S M Ng2,
  3. Yu Juan Dong2,
  4. Siew Chien Ng1,
  5. Wing Wa Leung2,
  6. Chung Wa Lee1,
  7. Yee Ni Wong2,
  8. Francis K L Chan1,
  9. Jun Yu1,
  10. Joseph J Y Sung1
  1. 1Institute of Digestive Disease and Department of Medicine and Therapeutics, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, China
  2. 2Department of Surgery, The Chinese University of Hong Kong, Hong Kong, China
  1. Correspondence to Professor Jun Yu, Institute of Digestive Disease, Department of Medicine and Therapeutics, Room 707, Li Ka Shing Institute of Health Sciences, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China; junyu{at}


Objective The detection of molecular markers in stool samples is a potential strategy for colorectal cancer (CRC) screening. This study evaluated the feasibility of detecting miR-21 and miR-92a in stool samples of patients with CRC or polyps.

Methods The reproducibility of detection and stability of stool-based microRNA were evaluated. Stool samples were collected from 88 patients with CRC, 57 patients with colorectal polyps and 101 healthy controls. MiRNA levels in CRC tissues and stool samples were detected by real-time quantitative reverse transcription PCR. Stool miR-21 and miR-92a levels were compared before and after the removal of tumour or advanced adenoma.

Results The study demonstrated that stool-based miRNA were stable with highly reproducible detection. The expression of miR-21 and miR-92a was significantly higher in CRC tissues compared with their adjacent normal tissues (p<0.0001). Patients with CRC had a significantly higher stool miR-21 level (p<0.01) and miR-92a level (p<0.0001) compared with normal controls. Stool miR-92a, but not miR-21, was significantly higher in patients with polyps than in controls (p<0.0001). At a cut-off value of 435 copies/ng of stool RNA, miR-92a had a sensitivity of 71.6% and 56.1% for CRC and polyp, respectively, and a specificity of 73.3%. In addition, the stool miR-92a level demonstrated a higher sensitivity for distal CRC than proximal CRC (p<0.05), and a higher sensitivity for advanced adenoma than minor polyps (p<0.05). Removal of tumour resulted in reduced stool miR-21 and miR-92a levels (p<0.01), and the removal of advanced adenoma resulted in a reduction of the stool miR-92a level (p<0.05).

Conclusion Stool miRNA are useful for screening CRC and polyps.

  • Colonic polyps
  • colorectal cancer
  • molecular biology
  • non-invasive biomarkers
  • screening
  • stool markers
  • stool microRNA

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  • Funding This study received financial support from the Institute of Digestive Disease and Li Ka Shing Institute of Health Sciences.

  • Competing interests None declared.

  • Patient consent Obtained.

  • Ethics approval This study was conducted with the approval of the institutional review board of the Chinese University of Hong Kong and the Hong Kong Hospital Authority.

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

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