Working Procedures

B. SCIENTIFIC REVIEW AND EVALUATION

6. Evaluation

For each screening procedure considered, a separate evaluation of the degree of evidence for efficacy and for effectiveness is formulated according to the following definitions.

It is recognized that the criteria for these evaluations, described below, cannot encompass all factors relevant to an evaluation. In considering all of the relevant scientific evidence, the Working Group may assign the screening procedure to a higher or lower category than a strict interpretation of these criteria would indicate.

  • Sufficient evidence for the efficacy or for the effectiveness of screening by a given procedure will apply when screening by this procedure is consistently associated with a reduction in mortality from the cancer or a reduction in the incidence of invasive cancer, and chance, bias, and confounding can be ruled out. In addition, for the evaluation of effectiveness, the balance of benefits and harms has been taken into account.

  • Limited evidence for the efficacy or for the effectiveness of screening by a given procedure will apply when screening by this procedure is associated with a reduction in mortality from the cancer or a reduction in the incidence of invasive cancer, or a reduction in the incidence of clinically advanced cancer, and chance, bias, and confounding cannot be ruled out with reasonable confidence. In addition, for the evaluation of effectiveness, the balance of benefits and harms has been taken into account.

  • Inadequate evidence for the efficacy or for the effectiveness of screening by a given procedure will apply when data on incidence or mortality are lacking, or when the number or quality of studies does not permit a conclusion.

  • Sufficient evidence that screening by a given procedure is not efficacious or effective will apply when any of the following cases hold:
      1. o The procedure does not result in earlier diagnosis than in the absence of screening;
        o The survival of cases detected at screening is no better than that of cases diagnosed routinely without screening;
        o The screening procedure is consistently associated with no reduction in mortality from or incidence of invasive cancer, and chance, bias, and confounding can be ruled out with reasonable confidence.
        o There is evidence showing that harms overweight benefits from the specific intervention.

     

    Updated 14 November 2017