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| References
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Prostate-screening,
benign enlargement and cancer |
| 5.
Carlson GD, Calvanese CB, Partin AW. An algorithm
combining age, total prostate-specific antigen (PSA), and
percent free PSA to predict prostate cancer: results on 4298
cases. Urology 1998;52:455-61.
Abstract: OBJECTIVES: To (1) determine if patient age and
total prostate-specific antigen (PSA) levels could enhance
the ability of percent free PSA to distinguish prostate
cancer from benign prostate disease within the 4.0 to 20
ng/mL total PSA range; (2) define the probability of prostate
cancer based on patient age, total PSA, and percent free
PSA; and (3) define a probability cutoff that distinguishes
benign from malignant prostate disease. METHODS: The 3773
urologically referred patients with serum PSA values between
4.0 and 20 ng/mL had a sextant biopsy diagnosed as either
prostatic carcinoma (1234) or benign prostatic disease (2539)
within 60 days of serum specimen collection. We created
a logistic regression model, using patient age, total PSA,
and percent free PSA, to assign a probability of prostate
cancer, and tested the model on an additional data set (525
patients) to calculate sensitivity and specificity. RESULTS:
An 18% probability cutoff detected 95% of malignant biopsies
and identified 34% of negative biopsies in the validation
set. This approach yielded an 11% percentage point increase
in specificity over percent free PSA alone. A 20% probability
cutoff detected 90% of malignant cases and identified 42%
of negative biopsies. CONCLUSIONS: A prostate cancer probability
based on age, total PSA, and percent free PSA is more effective
than percent free PSA alone in differentiating benign prostate
disease from prostate cancer. This model may assist physicians
and patients regarding the need for biopsy
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