Evaluation of cancer screening from the epidemiologic point of view

In Japan four kinds of cancer screening programs, namely screening programs for stomach cancer, uterine cancer, breast cancer and lung cancer, have been conducted under the Health and Medical Law for the Aged People. Now, however, it is demonstrated that cancer screening is not always effective in reducing cancer mortality. Therefore, new cancer screening programs, including colo-rectal cancer screening, should be evaluated by a well-designed study, like randomized controlled trial, before implementation as a public health policy.