We are about to embark on a project investigating the thoughts, feelings and behaviour of people when told they have a 'normal' result. We will manipulate the way in which feedback about the test result is presented.
According to this paper: Ann Fam Med. May 2009; 7(3): 212–222. Annals Journal Club
Cumulative Incidence of False-Positive Results in Repeated, Multimodal Cancer Screening by Jennifer Miller Croswell
are the results as follows: After 14 tests, the cumulative risk of having at least 1 false-positive screening test is 60.4% (95% CI, 59.8%–61.0%) for men, and 48.8% (95% CI, 48.1%–49.4%) for women. The cumulative risk after 14 tests of undergoing an invasive diagnostic procedure prompted by a false-positive test is 28.5% (CI, 27.8%–29.3%) for men and 22.1% (95% CI, 21.4%–22.7%) for women.
Look for NICE guidelines in the UK or the US Preventive Services Taskforce