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Vol.43 No.7 contents | Japanese/English |
 | Full Text of PDF (57K) Article in Japanese |
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[title in Japanese]
Tomotaka Sobue11Statistics and Cancer Control Division, Research Center for Cancer Prevention and Screening National Cancer Center, Japan
Objective and Methods. This aims to overview the effect of screening and related biases by reviewing previous findings. Results and Conclusion. The effect of screening is usually measured by site-specific mortality rate as an endpoint. Although comparisons of stage distribution or survival between screen-detected and symptom-detected cases are important measures in the entire process of screening evaluation, they will not be surrogates for mortality due to high possibility of suffering from various biases, such as self-selection bias, lead time bias, length bias. In particular, overdiagnosis has became of great concern not only as bias but also as harm due to screening. For evaluating mortality reduction, randomized controlled trial is a gold standard method. In the US and European countries, the results from any study design other than RCT, tend to be considered less valuable. However, it is important to evaluate how well the study designed, conducted and analyzed even for RCT. In the process of summarizing the evidence, checking internal validity is now concerned essential part of ranking the quality of study results.
key words: Cancer screening, Efficacy, Bias, Overdiagnosis
JJLC 43 (7): 1013-1017, 2003
