In 2003, prostate cancer (PCa) is estimated to be the most commonly diagnosed
cancer and third leading cause of cancer death in Canada. During PCa population
screening, approximately 25% of patients with a normal digital rectal examination (DRE)
and intermediate serum prostate specific antigen (PSA) level have PCa. Since all patients
typically undergo biopsy, it is expected that approximately 75% of these procedures are
unnecessary. The purpose of this study was to compare the degree of efficacy of clinical
tests and algorithms in stage II screening for PCa while preventing unnecessary biopsies
from occurring. The sample consisted of 201 consecutive men who were suspected of
PCa based on the results of a DRE and serum PSA. These men were referred for
venipuncture and transrectal ultrasound (TRUS). Clinical tests included TRUS, agespecific
reference range PSA (Age-PSA), prostate specific antigen density (PSAD), and
free-to-total prostate specific antigen ratio (%fPSA). Clinical results were evaluated
individually and within algorithms. Cutoffs of 0.12 and 0.15 ng/ml/cc were employed for
PSAD. Cutoffs that would provide a minimum sensitivity of 0.90 and 0.95, respectively
were utilized for %fPSA. Statistical analysis included ROC curve analysis, calculated
sensitivity (Sens), specificity (Spec), and positive likelihood ratio (LR), with
corresponding confidence intervals (Cl). The %fPSA, at a 23% cutoff ({ Sens=0.92; CI,
0.06}, {Spec=0.4l; CI, 0.09}, {LR=1.56; CI, O.ll}), proved to be the most efficacious
independent clinical test. The combination of PSAD (cutoff 0.15 ng/ml/cc) and %fPSA
(cutoff 23%) ({Sens=0.93; CI, 0.06}, {Spec=0.38; CI, 0.08}, {LR=1.50; CI, 0.10}) was
the most efficacious clinical algorithm. This study advocates the use of %fPSA at a
cutoff of 23% when screening patients with an intermediate serum PSA and benign DRE