The PDQ cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.

Introduction ¹

Added text to state these Levels of Evidence have been applied to the Screening for Oral Cancer, Prevention of Esophageal Cancer, Prevention of Oral Cancer, and Prevention of Skin Cancer summaries.

Revised text to state that the evidence that indicates, within a narrow range, the direction and magnitude of the effect on health outcomes is termed "solid" evidence and that the evidence that allows either no estimate at all or only an estimate that is very broad is termed "inadequate."

Evaluation of Evidence ²

Added text to describe examples for stating evidence of benefits and evidence of harms.