Colonoscopy reduced distal colorectal cancer risk and excess cancer risk associated with family history
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Colonoscopy efficacy at preventing proximal colorectal cancer (CRC) is questioned, and little is known about efficacy in high-risk versus medium-risk populations. We investigated the relationship between colonoscopy screening, family history of colorectal cancer (FHCC), and CRC risk by site.
Among 92,078 women of the E3N prospective cohort, 692 CRCs have been diagnosed after a median follow-up of 15.4 years. Cox proportional hazard models estimated adjusted hazards ratios according to subsites of cancer and FHCC.
A personal history of colonoscopy (PHC; n = 37,470) was associated with decreased rectal and distal colon cancer risks (hazard ratio (HR) = 0.57; 95 % Confidence Interval (CI) = 0.42–0.78 and HR = 0.37; 95 % CI = 0.26–0.52, respectively), but not proximal colon cancer risk (HR = 0.87; 95 % CI = 0.64–1.18). In women with no prior colonoscopy, those with FHCC had a 80 % higher CRC risk than those without FHCC. In women with previous colonoscopy, CRC risk was similar in women with and without FHCC (p for interaction = 0.04).
Results showed colonoscopy ability to prevent distal cancers, but not proximal cancers in women. Colonoscopy screening also reduced the excess risk of women with FHCC to that of women with no FHCC.
KeywordsColorectal cancer Colonoscopy Family history Prospective study Screening Efficacy
The E3N cohort is being carried out with the financial support of the “Mutuelle Générale de l’Education Nationale” (MGEN); European Community; French League against Cancer (LNCC); Gustave Roussy Institute (IGR); French Institute of Health and Medical Research (Inserm). Sophie Morois was supported by a doctoral grant from the French ministry of research. The authors are indebted to all participants for providing the data used in the E3N Study and to practitioners for providing pathology reports. They are grateful to M. Fangon, L. Hoang, R. Chait and M. Niravong for their technical assistance.
Conflict of interest
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