2011, Number 5
Specificity of PCA3 determination in urine for prostate cancer detection in Mexican patients
Saavedra-Briones DV, Rodríguez-Dorantes M, Morales-Montor JG, Salido-Guadarrama I, Merayo-Chalico CE, Hernández-Castellanos Víctor A, Sánchez-Turati Gustavo J, Santana-Ríos Z, Urdiales-Ortiz A, Fulda-Graue S, Ahumada-Tamayo S, Fernández-Noyola G, Martínez JA, Cantellano-Orozco M, Pacheco-Gahbler C
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Language: Spanish
References: 17
Page: 268-273
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ABSTRACT
Background: Prostate cancer holds first place as cause of death from neoplasms, ahead of cancer of the trachea, bronchial tubes, and lung. Specificity of prostate specific antigen and rectal examination varies from 24-37%. First biopsy is negative in over 75% of men with prostate specific antigen values ranging from 2.5-10 ng/mL or with suspicious rectal examination. Thus biopsy positive predictive value is very low. PCA3 gene determination in urine has shown 72% specificity and 58% sensitivity.Objective: To establish clinical usefulness through measuring the specificity of PCA3 determination in urine for prostate cancer diagnosis in biopsy of Mexican patients at the Hospital General “Dr. Manuel Gea González”.
Methods: A total of one hundred and fifty-seven patients with serum prostate specific antigen above 4 ng/mL or abnormal rectal examination were included in the study. The first 20-30 mL of urine were collected after prostate massage prior to transrectal ultrasound-guided biopsy. Twelve cores were taken from each patient. Samples were deposited in tubes containing 20 mL of nucleic acid stabilizing solution. PCA3 rate was calculated with relative expression of PCA3 mRNA. PCA3 performance was evaluated in terms of sensitivity and specificity when comparing results with biopsy results.
Results: Of the one hundred and fifty-seven patients, thirty-nine of them (25%) had biopsies that were positive for cancer, and three patients had undetermined or negative PCA3. Gleason score was 3+3 in nineteen patients (49%), 4+3 in one patient (2.5%), 3+5 in one patient (2.5%), 4+3 in three patients (8%), 4+4 in ten patients (26%), 5+4 in one patient (2.5%), and 5+5 in one patient (2.5%). Area under the curve in the receiver operating characteristic curve for PCA3 was 0.72 ( 95% CI 0.59-0.85) with a P=0.005. Total serum prostate specific antigen showed an area under the curve of 0.69 (95% CI 0.52-0.86). Receiver operating characteristic curve was used to determine sensitivity and specificity of the test for PCA3 with different cut-off points. Using 26 as cut-off point, the test showed 68% sensitivity and 74% specificity. Positive predictive value for PCA3 was 45% and negative predictive value was 94%.
Conclusions: Specificity and negative predictive value for the PCA3 test showed it can be useful as a tumor marker in urine, increasing precision in prostate cancer diagnosis.
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