Efficacy of lower cut off value of serum prostate specific antigen in diagnosis of prostate cancer

Abstract

Indications of prostate biopsy are high serum prostate specific antigen (PSA) value and or abnormal digital rectal examination (DRE) findings. Although serum PSA value of 4 ng/ml is the most commonly used threshold for recommending prostate biopsy, significant proportion of men harbor prostate cancer even when their serum PSA values are less than 4.0 ng/ml. Therefore present study was designed to determine the performance status of serum PSA in lower cut-off values. This hospital based prospective study was conducted in the Department of Urology of Bangabandhu Sheikh Mujib Medical University (BSMMU) and Comfort Nursing Home Pvt. Ltd, Dhaka from July 2009 to October 2010. Two hundred six male patients aged over 50 years having lower urinary tract symptoms (LUTS) and serum PSA more than 2.5 ng/ml were prepared for prostate biopsy. Trans rectal ultrasound (TRUS) guided biopsy was done. The test statistics used to analyze the data were descriptive statistics, sensitivity, specificity, positive and negative predictive value, ROC curve. For all analytical tests, the level of significance was set at 0.05 and p<0.05 was considered significant. In 2.5-4 serum PSA range, 28.26% (13 out of 46) of all malignancy were found, which would be missed if we take cut off value 4. At 2.5 PSA cut-off, Sensitivity 91.3%, Specificity 14.37%, PPV 23.46%, NPV 85.18%, Efficacy 31.55%. At 4 PSA cut-off value, Sensitivity 71.73%, Specificity 46.25%, PPV 27.73%, NPV 85.05%, Efficacy 51.94%. So it can be concluded that, for early diagnosis of prostate cancer cut-off value of serum PSA of 2.5 ng/ml can be recommended as an indication for prostate biopsy. DOI: http://dx.doi.org/10.3329/bmrcb.v38i3.14333 Bangladesh Med Res Counc Bull 2012; 38(3): 90-93 (December)