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    STUDY LEVELS OF EVIDENCE (LOE)                                                            tivitamin component (this study is
    From the Centre for Evidence-Based                Vitamins E and C and                    still ongoing). Complete follow-up
    Medicine, Oxford. For the most up-to-             Selenium Do Not Reduce                  occurred for 98% of men at 8 years.
    date levels of evidence, see www.cebm.
    net/levels_of_evidence.asp)                       Risk of Prostate or Total               Individuals assessing outcomes
                                                      Cancer in Men                           remained masked to treatment
    Therapy/Prevention/Etiology/Harm:                                                         group assignment. Using intention-
    1a: Systematic reviews of randomized              Clinical Question                       to-treat analysis, neither vitamin
         controlled trials                                Do vitamins E and C or sele-        E nor C had any significant effect
    1b: Individual randomized controlled              nium, alone or in combination,          on the incidence of prostate can-
    1c: All or none randomized controlled
                                                      reduce the risk of prostate cancer or   cer, total cancer, or all-cause mor-
         trials                                       total cancer in men?                    tality. Neither vitamin significantly
    2a: Systematic reviews of cohort studies                                                  reduced the individual incidence of
    2b: Individual cohort study or low-               Bottom Line                             colorectal, lung, bladder, or pancre-
         quality randomized controlled
                                                         In this large, well-designed, ran-   atic cancer. In secondary outcome
    2c: “Outcomes” research, ecological
         studies                                      domized trial, vitamins E and C and     analyses, vitamin E was associated
                                                      selenium, alone or in combination,      with a significantly increased risk
    Diagnosis:                                        did not reduce the risk of prostate     of hemorrhagic stroke. The study
    1a: Systematic review of level-1                  cancer, total cancer, or all-cause      was designed to have a greater than
         diagnostic studies                           mortality. (LOE = 1b)                   80% power to detect a 13% reduc-
    1b: Independent blind comparison
         of an appropriate spectrum
                                                                                              tion in the risk of total cancer. A
         of consecutive patients, all of              Study Design                            related article in the same jour-
         whom have undergone both the                    Randomized controlled trial          nal (Lippman SM, et al. JAMA.
         diagnostic test and the reference
         standard, or a clinical decision rule
                                                      (double-blinded)                        2009;301:39-51) also reported that
         not validated on a second set of                                                     neither selenium nor vitamin E,
         patients                                     Funding                                 alone or together, reduced the risk
    1c: Absolute SpPins and SnNouts                     Industry + govt                       of prostate cancer.
    2a: Systematic review of level >2
    2b: Independent blind or objective
         comparison, study confined
                                                      Allocation                              REFERENCE
                                                         Concealed                            Gaziano JM, Glynn RJ, Christen WG, et al. Vita-
         to a narrow spectrum of study
                                                                                              mins E and C in the prevention of prostate and
         individuals, or a diagnostic clinical
                                                                                              total cancer in men. The Physicians’ Health
         rule not validated in a test set
                                                      Setting                                 Study II randomized controlled trial. JAMA.
                                                         Outpatient (any)                     2009;301:52-62.
    1a: Systematic review of inception
         cohort studies                               Synopsis
    1b: Individual inception cohort study         
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