Operating characteristics of prostate-specific antigen in men with an
initial PSA level of 3.0 ng/ml or lower.

Thompson IM, Ankerst DP, Chi C, Lucia MS, Goodman PJ, Crowley JJ, Parnes
HL, Coltman CA Jr.

Department of Urology, University of Texas Health Science Center at San
Antonio, TX 78229, USA. thompsoni@uthscsa.edu

CONTEXT: Three fourths of US men older than 50 years have been screened
with prostate-specific antigen (PSA) for prostate cancer. OBJECTIVE: To
estimate the receiver operating characteristic (ROC) curve for PSA.

DESIGN, SETTING, AND PARTICIPANTS: Calculation of PSA ROC curves in the
placebo group of the Prostate Cancer Prevention Trial, a randomized,
prospective study conducted from 1993 to 2003 at 221 US centers.
Participants were 18 882 healthy men aged 55 years or older without
prostate cancer and with PSA levels less than or equal to 3.0 ng/mL and
normal digital rectal examination results, followed up for 7 years with
annual PSA measurement and digital rectal examination. If PSA level
exceeded 4.0 ng/mL or rectal examination result was abnormal, a prostate
biopsy was recommended. After 7 years of study participation, an
end-of-study prostate biopsy was recommended in all cancer-free men.

MAIN OUTCOME MEASURES: Operating characteristics of PSA for prostate
cancer detection, including sensitivity, specificity, and ROC curve.

RESULTS: Of 8575 men in the placebo group with at least 1 PSA
measurement and digital rectal examination in the same year, 5587
(65.2%) had had at least 1 biopsy; of these, 1225 (21.9%) were diagnosed
with prostate cancer. Of 1213 cancers with Gleason grade recorded, 250
(20.6%) were Gleason grade 7 or greater and 57 (4.7%) were Gleason grade
8 or greater. The areas under the ROC curve (AUC) for PSA to
discriminate any prostate cancer vs no cancer, Gleason grade 7 or
greater cancer vs no or lower-grade cancer, and Gleason grade 8 or
greater cancer vs no or lower-grade cancer were 0.678 (95% confidence
interval [CI], 0.666-0.689), 0.782 (95% CI, 0.748-0.816), and 0.827 (95%
CI, 0.761-0.893), respectively (all P values <.001 for AUC vs 50%). For
detecting any prostate cancer, PSA cutoff values of 1.1, 2.1, 3.1, and
4.1 ng/mL yielded sensitivities of 83.4%, 52.6%, 32.2%, and 20.5%, and
specificities of 38.9%, 72.5%, 86.7%, and 93.8%, respectively.
Age-stratified analyses showed slightly better performance of PSA in men
younger than 70 years vs those 70 years or older with AUC values of
0.699 (SD, 0.013) vs 0.663 (SD, 0.013) (P = .03).

CONCLUSION: There is no cutpoint of PSA with simultaneous high
sensitivity and high specificity for monitoring healthy men for prostate
cancer, but rather a continuum of prostate cancer risk at all values of
PSA.
PMID: 15998892 [PubMed - indexed for MEDLINE]

knowledge is power - growing old is mandatory - growing wise is optional    
"Many more men die with prostate cancer than of it. Growing old is
invariably fatal. Prostate cancer is only sometimes so."
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