Role of Serum Total PSA (Prostate Specific Antigen) and Free to Total PSA Ratio in the Diagnosis of Carcinoma Prostate.
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Date
2011
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Abstract
The objective of the study was to evaluate and compare the role of total and free/total ratio
of serum prostate specific antigen level in diagnosing carcinoma prostate. A cross sectional
study was conducted at the Department of Biochemistry, Dhaka Medical College (DMC)
with collaboration of the Department of Urology, Dhaka Medical College Hospital
(DMCH), Dhaka from July 2008 to June 2009. This study was carried out on 60 patients
above 50 years of age who attended the Department of Urology, Dhaka Medical College
Hospital, complaining of irritative or obstructive lower urinary tract symptoms (LUTS)
suspected as clinically benign prostatic hyperplasia (BPH) or cancer prostate. It was aimed
to assess the role of total and free/total ratio of serum PSA in diagnosis of BPH and
carcinoma prostate with reference to histological diagnosis. All the cases were evaluated by
history, physical examination including digital rectal examination, serum prostate specific
antigen level, transabdominal/ trans-rectal ultra- sonogram. From all patients, blood sample
were collected before digital rectal examination or any per urethral manipulation. Final
diagnosis was obtained by histo-pathological examination, specimen being obtained by perrectal
biopsy with biopsy-gun. Histopathological examination detected prostate cancer in 20
out of 60 patient and 17 of these Cap 20 have a total PSA 4 ng/ml and only 3 have total
PSA 4 ng/ml. 18 of these 20 have free to total ratio 0.16 and 02 have f/t ratio 0.16.
Among 60 patients, 40 patients were detected BPH on histopathological diagnosis. 20 of
these BPH patient have tPSA 4 ng/ml and 20 of BPH have tPSA 4 ng/ml. 38 of 40 BPH
patient have f/t ratio>0.16 and 2 of 40 patient are f/t ratio 0.16. Receiver operating
characteristic analysis indicated a threshold f/t ratio 0.16 was optimum discriminatory
level. The sensitivity of total serum PSA (at cut off value of>4 ng/ml) in correctly
differentiating prostatic carcinoma of those who have the condition is 85%, while the
specificity of the test in correctly detecting those who do not have the disease is 50%. The
PPV is 45.9%, NPV is 87% and accuracy is 61.7%. The sensitivity of free/total serum
PSA (at cut off value of 0.16 ng/ml) in correctly differentiating prostatic carcinoma from
BPH is 90%, while the specificity of the test in correctly detecting those who do not have
prostatic carcinoma is 95%. The PPV of the test is 90% and the NPV of the test is 95%.
The overall accuracy of the test is 93.3%. This study showed significant difference of total
and free/total ratio of serum prostate specific antigen (PSA) in differentiating benign
prostatic hyperplasia (BPH) from carcinoma prostate. Receiver operating characteristic
curves showed advantage for the f/t PSA ratio when compared with total PSA in detecting
prostate cancer. From the study it may be concluded that total and f/t ratio of prostate
specific antigen (PSA) is a useful marker in diagnosis of carcinoma prostate. Free/total ratio
is more accurate than total PSA.
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Keywords
Benign Prostatic Hyperplasia (BPH), Carcinoma Prostate (CaP), Prostate Specific Antigen (PSA), Free to total ratio of PSA (f/t ratio)
Citation
Ferdousi S, Alim M A, Ferdous Z, Khatun A, Sultana N, Shahnaz A, Hossain M S. Role of Serum Total PSA (Prostate Specific Antigen) and Free to Total PSA Ratio in the Diagnosis of Carcinoma Prostate. Bangladesh Journal of Medical Biochemistry. 2011; 4(1): 21-26.