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    Colorectal Cancer Prevention (PDQ®): Prevention - Health Professional Information [NCI] - Overview


    There are no known harms from dietary modification, including reduction of fatty acids or meats and an increase in the intake of fiber, fruits, and vegetables.

    Study Design: Cohort and RCTs.
    Internal Validity: Good.
    Consistency: Good.
    External Validity: Good.

    Calcium supplementation


    The evidence is inadequate to determine whether calcium supplementation reduces the risk of CRC.

    Study Design: Pooled and individual prospective cohort studies, meta-analysis of three RCTs with adenoma recurrence as an outcome, and one large individual RCT in women with CRC as an outcome.
    Internal Validity: Good.
    Consistency: Poor; the RCT with CRC as an outcome [32] found no reduction in CRC incidence, while prospective cohort studies found a reduction in CRC incidence between high and low calcium groups; three RCTs found a reduction in adenoma recurrence with calcium supplementation.[33]
    External Validity: N/A.


    The evidence is fair that elemental calcium without vitamin D as a supplement in the level of 1,000 to 1,200 mg/day increases the risk of myocardial infarction. Based on fair evidence, calcium supplementation with vitamin D at doses less than 1,000 has few harms.

    Magnitude of Effect: In a meta-analysis of RCTs of calcium alone, the risk of myocardial infarction was increased from 4.8% to 5.8% (HR = 1.31; 95% CI, 1.02-1.67).

    Study Design: Pooled and individual prospective cohort studies plus RCTs.
    Internal Validity: Good.
    Consistency: Poor (one meta-analysis of 11 RCTs for calcium alone found increased myocardial infarction; no other individual studies found this).[34]
    External Validity: Good.



    Based on solid evidence, statins do not reduce the incidence or mortality from CRC.

    Study Design: Meta-analyses of RCTs.[35,36,37]
    Internal Validity: Good.
    Consistency: Good.
    External Validity: N/A.


    Based on solid evidence, the harms of statins are small.

    Study Design: Observational studies,[38] multiple RCTs, and a review.[39]
    Internal Validity: Good.
    Consistency: Good.
    External Validity: Good.


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    This information is produced and provided by the National Cancer Institute (NCI). The information in this topic may have changed since it was written. For the most current information, contact the National Cancer Institute via the Internet web site at http:// cancer .gov or call 1-800-4-CANCER.

    WebMD Public Information from the National Cancer Institute

    Last Updated: May 28, 2015
    This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
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