Serial prostate specific antigen screening for prostate cancer: A computermodel evaluates competing strategies

Purpose: We compare prostate specific antigen (PSA) screening strategies in terms of expected years of life saved with screening, number of screens, n umber of false-positive screens and rates of over diagnosis, defined as det ection by PSA screening of patients who would never have been diagnosed wit hout screening. Materials and Methods: A computer model of disease progression, clinical di agnosis, PSA growth and PSA screening was used. Under baseline conditions, when screening is not considered, the model replicates clinical diagnosis a nd disease mortality rates recorded by the Surveillance, Epidemiology and E nd Results Program of the National Cancer Institute in the mid 1980s. Results: Biannual screening with PSA greater than 4.0 ng./ml. was projected to reduce the number of screens and false-positive tests by almost 50% rel ative to annual screening while retaining 93% of years of life saved. With annual screening use of an age specific bound for PSA to consider a test po sitive instead of the standard 4.0 ng./ml. was projected to reduce false-po sitive screens by 27% and over diagnosis by a third while retaining almost 95% of years of life saved. Sensitivity analyses did not change the relativ e efficacy of biannual screening. Conclusions: Under the model assumptions biannual PSA screening is a cost-e ffective alternative to annual PSA screening for prostate cancer. With annu al screening use of an age specific bound for PSA positivity appears to red uce false-positive results and over diagnosis rates sharply relative to a b ound of 4 ng./ml. while retaining most of the survival benefits.