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Prostate Cancer - part 4

Hầu hết các bác sĩ có liên quan đến sau này, trong đó bao gồm giới thiệu các xét nghiệm sàng lọc duy trì một quan hệ bệnh nhân-bác sĩ liên tục. Độ nhạy và độ đặc hiệu của một thử nghiệm cụ thể giúp đỡ để thiết lập hiệu quả của nó. | Ti P. Tenkeetal. former is performed with little regard for the risk profile of the individual patient. Most physicians are involved in the latter which consists of recommending screening tests maintaining a constant patient-physician relationship. The sensitivity and specificity of a specific test help to establish its effectiveness. Sensitivity is the equivalent of the proportion of the disease population who has a positive test true-positive rate . The particularity of a test equals the proportion of healthy patients who have a negative test truenegative rate . The terms sensitivity and specificity are only applied to situations in which the total number of cancers present in a given population is known. This is not the case in screening populations. The number needed in the denominator of the formulas that calculate sensitivity and specificity is often replaced by the number of men with positive or negative biopsy which is usually obtained by the use of a standard biopsy indication such as abnormal DRE or a PSA greater than or equal to 4.0 ng ml. More accurately if this expression is chosen for comparison purposes it should be termed relative sensitivity and relative specificity. Patients and clinicians are often more interested in the positive predictive value of a test which equals the proportion of patients with a positive test result who actually have the disease. The use of the term specificity in a situation in which the underlying prevalence of cancer is not known may be acceptable because of the usually large number of men who in fact do not have cancer. This minimizes the mistake made by applying this formula 40 . Criteria of Effective Screening Tests For a screening test to be effective certain criteria should be fulfilled 40 - The disease must constitute a significant public health problem with significant morbidity and mortality. It should have an available and acceptable treatment and the potential for cure must be greater among screen-detected .