Screening for cancer: future potential.

Much progress has been made in cancer screening over the past decade, but a great deal more needs to be done if screening is to make a major impact on worldwide cancer mortality. Where fully implemented, cytological screening for cervical precursor lesions has had a major impact on mortality. However, the cost and required infrastructure levels are high, and new approaches are needed if screening is to be effective in the developing world. Testing for the human papillomavirus and automated liquid based cytology offer great promise to improve quality, reduce overall cost and make screening more viable generally. Breast screening has been less successful, although useful mortality benefits have been achieved in women aged over 50 years. Full implementation in countries that can afford it will save lives, but radical new approaches will be needed to conquer breast cancer. Colorectal cancer screening offers the best hope of a major reduction in cancer mortality over the next decade. Less certainty exists about screening for other major cancers such as lung, prostate and ovary, but a range of potential approaches merit investigation.