Abstract
In this paper the evidence necessary to justify interventional prevention for cancer is discussed. In Japan, to date few trials with a design of RCT have been conducted in the field of cancer prevention. However, as it has been shown that preventive measures such as cancer screening and chemoprevention generally cause some harm and they are not always effective in reducing mortality, there should be evidence from good-quality RCTs showing that they do more good than harm before any new cancer screening and cancer prevention measures are implemented as public health services.
