The value of percentage free prostate specific antigen (PSA) in the detection of prostate cancer among patients with intermediate levels of total PSA (4.0–10.0 ng/mL) in Nigeria

Abstract

Objectives To assess the value of percentage free prostate-specific antigen (%fPSA) in the detection of prostate cancer among Nigerian men with an intermediate total PSA level (4–10 ng/mL), and to show if the optimum threshold for biopsy is different from Caucasian values when the widely used (six-core, digitally directed) prostate biopsy protocol in Nigerians is applied. Patients and methods The study included 105 patients aged >50 years, with a palpably benign prostate gland and intermediate levels of total PSA (4–10 ng/mL). These patients had a free PSA assay and a transrectal digitally directed six-core biopsy of the prostate. The %fPSA was calculated and the optimum threshold value for detecting prostate cancer was determined. Results The mean (SD) age of the patients was 64.4 (6.6) years and their mean (SD) total PSA level was 6.6 (1.7) ng/mL. Of these men 14 (13.3%) had cancer of the prostate detected by the prostate biopsy. The %fPSA level related directly to sensitivity values but inversely to the specificity and the positive predictive values. The best threshold of %fPSA for detecting cancer in these men was <40%, with a sensitivity of 100%, specificity of 93.4% and a positive predictive value of 70% ( P < 0.05). Conclusions In evaluating Nigerian patients with a palpably benign prostate gland and within the intermediate total PSA range, when digitally directed biopsy protocol is adopted, a %fPSA threshold of <40% will detect significant percentage of those with prostate cancer, with a minimal number of unnecessary biopsies. This value differs from that reported in western studies in which transrectal ultrasonography-directed biopsy was used.

PSMA expression: a potential ally for the pathologist in prostate cancer diagnosis

“…However, these parameters are not 100% accurate in discriminating between low- and high-risk patients, indicating the need for companion biomarkers to better predict disease evolution and improve patient stratification. Although PSMA is a promising biomarker in that it is more specific than PSA, its role in PCa diagnosis and evolution has yet to be confirmed 2 , 3 . In fact, differences in PSMA expression in terms of cellular or tissue localization may depend on the type of antibody used or sample analyzed.…”

“…Nonetheless, serum PSA is burdened by low accuracy because it is an organ-specific rather than tumor-specific biomarker and can also show an abnormal increase in the presence of benign prostatic hyperplasia. This is one of the most important limitations of PSA for diagnostic/prognostic purposes 2 , 3 .…”

Prostate-Specific Antigen Density: A Measurement to Differentiate Benign Hypertrophy of Prostate from Prostate Carcinoma

“…Literature shows that in the intermediate zone the occurrence of prostate cancer is higher in those individuals with low prostate volume. [14][15][16] PSA was approved by Food and Drug Administration (FDA) for use in prostate screening way back in 1994 and it is the most commonly used parameter for prostate cancer screening in the United States. 1,17,18 Catalona et al in a metacentric study done on 6,374 men of 50 years of age and older showed that 72% or (93/130) of prostate cancers detected by PSA and DRE were organ-confined indicating an early stage of cancer.…”

Editorial comment

“…The results for prostate volume obtained using transabdominal ultrasonography are as stated in the Results and discussion sections [3] . Unlike with standard TRUS, an accurate measurement of prostate volume for further analysis of volume was not possible because transabdominal scans of the prostate were used.…”