The accuracy of the increased prostate specific antigen level (greater than or equal to 20 ng./ml.) in predicting prostate cancer: is biopsy always required?
OBJECTIVE
Urologists are often referred patients who initially present with an extremely high serum prostate specific antigen (PSA) level. Despite a presumptive diagnosis of prostate cancer, many of these men undergo biopsy to obtain a tissue diagnosis before treatment with androgen ablative therapy. We examined a data base of men undergoing prostate biopsy to determine the accuracy of high PSA levels (greater than or equal to 20 ng./ml.) in predicting prostate cancer.


METHODS
We reviewed the records of 1,250 consecutive patients undergoing transrectal ultrasound guided prostate biopsy at 1 institution. From this data base we identified all patients with PSA greater than or equal to 20 ng./ml. at the time of prostate biopsy. The accuracy of PSA in predicting cancer was determined by calculating positive predictive values for PSA ranges and PSA cutoffs.


RESULTS
We identified 187 men (15%) presenting with PSA greater than or equal to 20 ng./ml. Of these 187 men 157 (84.0%) were diagnosed with prostate cancer on initial biopsy. Due to a negative initial biopsy, yet a high suspicion of cancer, 12 (6.4%) patients underwent at least 1 repeat biopsy. Of these 12 men 6 (50%) were diagnosed with cancer on repeat biopsy. Overall, 163 of the 187 men (87.2%) were diagnosed with prostate cancer by biopsy. Stratified by PSA ranges, positive predictive values were 73.6% for 20 to 29.9, 90.3% for 30 to 39.9, 93.8% for 40 to 49.9, 100% for 50 to 99.9, 95% for 100 to 199.9 and 100% for greater than or equal to 200 ng./ml. Using PSA cutoffs positive predictive values were 95.7% for PSA greater than or equal to 30, 97.6% for PSA greater than or equal to 40 and 98.5% for PSA greater than or equal to 50 ng./ml.


CONCLUSIONS
Serum PSA, when increased above 50 ng./ml., is 98.5% accurate in predicting the presence of prostate cancer on tissue biopsy. Nonetheless, since transrectal prostate biopsy has a low complication rate and is relatively well tolerated, we recommend continuing to biopsy most patients with high PSA levels. However, carefully selected elderly patients on chronic anticoagulation, with severe co-morbidities or presenting with spinal cord compression may not require biopsy before androgen ablative therapy since PSA is highly accurate in diagnosing prostate cancer at levels greater than 50 ng./ml.
Gerstenbluth
Robert E
RE
Cleveland Veterans Affairs Medical Center, Case Western Reserve University School of Medicine, Ohio, USA.
Seftel
Allen D
AD
Hampel
Nehemia
N
Oefelein
Michael G
MG
Resnick
Martin I
MI
D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood*; D001707:Biopsy, Needle; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011467:Prostate / Q000473:pathology*; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000473:pathology; D012016:Reference Values
D014408:Biomarkers, Tumor; D017430:Prostate-Specific Antigen