Development and Evaluation of Cancer Prevention Strategies in Japan
Evaluation Method
Collection of literature: we pick out, from the literature recorded in MEDLINE database, papers on studies of cancer in general and major cancers [lung, gastric, colon, liver, breast (female) cancers, etc.], which have been conducted using methods that can be included for evaluation (cohort studies or case-control studies). For each of the above paper, we evaluate on A. Credibility as a scientific basis, B. The strength of the association between contributing factors and cancer.
Change of evaluation: In the research group, we conduct systematic reviews on already published papers, and determine the evaluation in accordance with the assessment criteria. If new evidence has been accumulated thereafter, we reexamine the evaluation at the group meeting when necessary. In line with changes in evaluations, the “Evaluation of Evidence” section of the homepage will be revised, and the change history recorded.
Basis of Evaluation
A. Credibility as a Scientific Basis |
|
|---|---|
Convincing |
The results of epidemiological studies are consistent, and there are almost no contradicting results. There are a substantial number of studies. Biological explanations can be used to understand the results. |
Probable |
The results of epidemiological studies are fairly consistent, but there are inadequacies in the methods (the study period is too short, not sufficient number of studies, not sufficient number of subjects, follow-up is incomplete, etc.), or there are multiple contradicting results, and the results, therefore, are not conclusive. |
Possible |
Studies are limited to case-control or cross-sectional studies. The number of observational studies is not sufficient. The results are supported by studies other than epidemiological studies, such as clinical studies or experimental results. To confirm the results, more epidemiological studies needs to be conducted, and the results need to be biologically explained. |
Insufficient |
Only 2 or 3 incomplete studies have been conducted. For confirmation, studies needs to be done through methods with higher credibility. |
|
Created based on the criteria of WHO/FAO Expert Consultation
|
|
B. Strength of the association between contributing factors and cancer |
|
|---|---|
Strong↓↓↓ or ↑↑↑ |
The relative risk is less than 0.5, or is greater than 2.0, and is statistically significant. |
Moderate↓↓ or ↑↑ |
The relative risk is less than 0.5, or is greater than 2.0, and is not statistically significant. Alternatively, the relative risk is 0.5 or greater and less than 0.67, or greater than 1.5 and 2.0 or less and yet is statistically significant. |
Weak↓ or ↑ |
The relative risk is 0.5 or greater and less than 0.67, or greater than 1.5 and 2.0 or less, and is not statistically significant. Alternatively, the relative risk is 0.67 or greater and 1.5 or less, and yet is statistically significant. |
Non-linear |
The relative risk is 0.67 or greater and 1.5 or less, and is not statistically significant. |
