The Principles of Screening The condition should be an important health problem There should be a latent stage of the disease Disease The natural history of the disease should be adequately Test There should be a test or examination for the condition The test should be acceptable to the population There should be a treatment for the condition R Treatment Facilities for diagnosis and treatment should be available There should be an agreed policy on whom to treat ?s Cost The total cost of finding a case should be economicall balanced in relation to medical expenditure as a whole Case-finding should be a continuous process, not just a"once pRogramm and for all "pre 8 March 2018 6/80
8 March 2018 6/80 The Principles of Screening – The condition should be an important health problem. – There should be a latent stage of the disease. – The natural history of the disease should be adequately understood. – There should be a test or examination for the condition. – The test should be acceptable to the population. – There should be a treatment for the condition. – Facilities for diagnosis and treatment should be available. – There should be an agreed policy on whom to treat. – The total cost of finding a case should be economically balanced in relation to medical expenditure as a whole. – Case-finding should be a continuous process, not just a "once and for all" project
十Ds sease The disease must be an important health problem o There should be a recognizable latent or early symptomatic stage The natural history of the disease, including latent to declared disease, should be adequately understood o Facilities for diagnosis and treatment should be available o There should be a test or examination for the condition and the test should be acceptable to the population 8 March 2018 7/80
8 March 2018 7/80 The disease must be an important health problem. There should be a recognizable latent or early symptomatic stage. The natural history of the disease, including latent to declared disease, should be adequately understood. Facilities for diagnosis and treatment should be available. There should be a test or examination for the condition and the test should be acceptable to the population
A suitable disease for screening ◆Why? 8 March 2018 8/80
8 March 2018 8/80 A suitable disease for screening Why?
i Colorectal Cancer 9 CRC is the third leading cause of cancer death worldwide o a slow progression from detectable and curable precancerous lesions, advanced adenoma o 5 years survival rate depends on the stage at diagnosis StageI>90% Stage II 70-85% Stage Ill 25-65% Stage Iv<10% 8 March 2018 9/80
8 March 2018 9/80 Colorectal Cancer CRC is the third leading cause of cancer death worldwide A slow progression from detectable and curable precancerous lesions, advanced adenoma 5 years survival rate depends on the stage at diagnosis – Stage I > 90 % – Stage II 70-85% – Stage III 25-65% – Stage IV < 10%
Lead time bias Clinical Onset of B detectable diagnosis dIsease p symptoms Lead time Benefit Earl Death diagnosis Screening 8 March 2018 10/80
8 March 2018 10/80 Lead time bias Onset of disease Begin detectable phase Clinical diagnosis symptoms Early diagnosis Death Death Lead time survival Benefit Screening