Long-term risk of colorectal cancer in individuals with serrated polyps.
OBJECTIVE
Although serrated polyps may be precursors of colorectal cancer (CRC), prospective data on the long-term CRC risk in individuals with serrated polyps are lacking.


METHODS
In a population-based randomised trial, 12,955 individuals aged 50-64 years were screened with flexible sigmoidoscopy, while 78 220 individuals comprised the control arm. We used Cox models to estimate HRs with 95% CIs for CRC among individuals with ≥1 large serrated polyp (≥10 mm in diameter), compared with individuals with adenomas at screening, and to population controls, and multivariate logistic regression to assess polyp risk factors for CRC.


RESULTS
A total of 103 individuals had large serrated polyps, of which 81 were included in the analyses. Non-advanced adenomas were found in 1488 individuals, advanced adenomas in 701. Median follow-up was 10.9 years. Compared with the control arm, the HR for CRC was 2.5 (95% CI 0.8 to 7.8) in individuals with large serrated polyps, 2.0 (95% CI 1.3 to 2.9) in individuals with advanced adenomas and 0.6 (95% CI 0.4 to 1.1) in individuals with non-advanced adenomas. A large serrated polyp was an independent risk factor for CRC, adjusted for histology, size and multiplicity of concomitant adenomas (OR 3.3; 95% CI 1.3 to 8.6). Twenty-three large serrated polyps found at screening were left in situ for a median of 11.0 years. None developed into a malignant tumour.


CONCLUSIONS
Individuals with large serrated polyps have an increased risk of CRC, comparable with individuals with advanced adenomas. However, this risk may not be related to malignant growth of the serrated polyp.


BACKGROUND
The Norwegian Colorectal Cancer Screening trial is registered at clinicaltrials.gov (NCT00119912).
Department of Medicine, Sørlandet Hospital, Kristiansand, Norway Institute of Health and Society, University of Oslo, Oslo, Norway.
Øyvind
Ø
Holme
Department of Medicine, Sørlandet Hospital, Kristiansand, Norway Institute of Health and Society, University of Oslo, Oslo, Norway Department of Transplantation Medicine, Oslo University Hospital, Oslo, Norway Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA.
Michael
M
Bretthauer
Department of Pathology, Oslo University Hospital, Oslo, Norway Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
Tor J
TJ
Eide
Department of Pathology, Oslo University Hospital, Oslo, Norway Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
Else Marit
EM
Løberg
Department of Pathology, Oslo University Hospital, Oslo, Norway.
Krzysztof
K
Grzyb
Institute of Health and Society, University of Oslo, Oslo, Norway Department of Transplantation Medicine, Oslo University Hospital, Oslo, Norway.
Magnus
M
Løberg
Institute of Health and Society, University of Oslo, Oslo, Norway Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA Telemark Hospital, Skien, Norway.
Mette
M
Kalager
Institute of Health and Society, University of Oslo, Oslo, Norway Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
Hans-Olov
HO
Adami
Department of Medicine, Telemark Hospital, Kragerø, Norway.
Øystein
Ø
Kjellevold
Institute of Health and Society, University of Oslo, Oslo, Norway Telemark Hospital, Skien, Norway Cancer Registry of Norway, Oslo, Norway.
Geir
G
Hoff
D000236:Adenoma / Q000175:diagnosis / Q000453:epidemiology* / Q000473:pathology* / Q000601:surgery; D000328:Adult; D001706:Biopsy; D003111:Colonic Polyps / Q000175:diagnosis / Q000453:epidemiology* / Q000473:pathology* / Q000601:surgery; D003113:Colonoscopy / Q000706:statistics & numerical data; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000453:epidemiology* / Q000473:pathology* / Q000601:surgery; D018450:Disease Progression; D055088:Early Detection of Cancer; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D008403:Mass Screening / Q000706:statistics & numerical data; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D012812:Sigmoidoscopy / Q000706:statistics & numerical data