Some signals cannot wait: effects of a national campaign on early detection of cancer among Dutch adults (>55 years).

Background: The present study examined the effects of the campaign "early detection of cancer" on knowledge, attitudes, awareness, and intention to perform passive detection and timely seeking medical help. Further, the campaign was evaluated on recall and recognition and the various campaign components were evaluated.

Methods: A longitudinal study using a Solomon four-group design among 784 Dutch adults aged 55 years and older was conducted.