Making informed decisions about breast and prostate cancer screening requires 
knowledge of its benefits. However, country-specific information on public 
knowledge of the benefits of screening is lacking. Face-to-face 
computer-assisted personal interviews were conducted with 10,228 persons 
selected by a representative quota method in nine European countries (Austria, 
France, Germany, Italy, the Netherlands, Poland, Russia, Spain, and the United 
Kingdom) to assess perceptions of cancer-specific mortality reduction associated 
with mammography and prostate-specific antigen (PSA) screening. Participants 
were also queried on the extent to which they consulted 14 different sources of 
health information. Correlation coefficients between frequency of use of 
particular sources and the accuracy of estimates of screening benefit were 
calculated. Ninety-two percent of women overestimated the mortality reduction 
from mammography screening by at least one order of magnitude or reported that 
they did not know. Eighty-nine percent of men overestimated the benefits of PSA 
screening by a similar extent or did not know. Women and men aged 50-69 years, 
and thus targeted by screening programs, were not substantially better informed 
about the benefits of mammography and PSA screening, respectively, than men and 
women overall. Frequent consulting of physicians (r = .07, 95% confidence 
interval [CI] = 0.05 to 0.09) and health pamphlets (r = .06, 95% CI = 0.04 to 
0.08) tended to increase rather than reduce overestimation. The vast majority of 
citizens in nine European countries systematically overestimate the benefits of 
mammography and PSA screening. In the countries investigated, physicians and 
other information sources appear to have little impact on improving citizens' 
perceptions of these benefits.