AN ALGORITHM FOR PROSTATE-CANCER DETECTION IN A PATIENT POPULATION USING PROSTATE-SPECIFIC ANTIGEN AND PROSTATE-SPECIFIC ANTIGEN DENSITY

Prostate-specific antigen (PSA) is the most accurate serum marker for cancer of the prostate (CaP). However, its sensitivity and specificity are suboptimal, especially at values ranging between 4.1 and 10.0 ng/ ml (monoclonal), because benign prostatic hypertrophy and hyperplasia (BPH) and CaP frequently coexist in this range. This study was underta ken to determine the value of incorporating prostate volume measuremen ts with serum PSA levels in a quotient (PSA/volume) entitled PSA densi ty (PSAD). A total of 3140 patients were analyzed and stratified by se rum PSA, digital rectal examination (DRE), transrectal prostate ultras ound (TRUS), TRUS volume determination and PSAD. All patients were ref erred for evaluation and therefore do not represent a screened populat ion. Patients underwent prostate biopsies when abnormalities in TRUS o r DRE were detected. Although both PSA and PSAD have statistical signi ficance when the serum PSA value is less than or equal to 4.0 ng/ml, n either has clinical significance in differentiating BPH from CaP. At s erum levels ranging between 4.1 and 10.0 ng/ml, PSA has no ability to differentiate BPH from CaP, whereas PSAD does so with statistical and clinical significance. When the PSA value is between 10.1 and 20.0 ng/ ml, only PSAD is statistically significant. When PSA exceeds 20 ng/ml, PSAD is redundant. We conclude that all patients with an abnormality on DRE or TRUS should undergo prostate biopsy. If the PSA value is les s than or equal to 4.0 ng/ml, TRUS and PSAD are not warranted and rout ine biopsy is not recommended. For intermediate PSA levels, 4.1-10.0 n g/ml, TRUS, TRUS prostate volume, and PSAD are important. The use of P SAD provides unique information regarding the need for biopsy and the likelihood of CaP. At PSA levels ranging between 10.1 and 20.0 ng/ml, PSAD will identify those patients who are less likely to have CaP, but all should undergo biopsy. If the PSA value is > 20 ng/ml, all patien ts should undergo a biopsy.