TRUS Biopsy Yield in Indian Population: A Retrospective Analysis

Abstract

Introduction: The reported cancer detection rate of TransRectal Ultrasonography (TRUS) biopsies (TRUS biopsy yield) has been around 30 percent in western countries. However it is much lower in Asian countries, including India. Hence a larger proportion of patients in India undergo unnecessary biopsies. Aims: To find out the cancer detection rate of TRUS biopsy (TRUS biopsy yield) in contemporary Indian population. Also, to study the positive predictive values at different serum ProstateSpecific Antigen (PSA)/PSA Density (PSAD) cut off levels and suspicious Digital Rectal Examination (DRE) findings. Materials and Methods: This retrospective study was carried out in a tertiary care institute. All symptomatic patients who underwent TRUS guided biopsy for indication of raised serum PSA level (>4 ng/ml) or suspicious DRE findings (nodule, irregularity, hard consistency, immobile rectal mucosa) from January 2012 to December 2014 were included. For serum PSA range (4-10) ng/ml, TRUS guided biopsy was done in patients with percent free/total PSA < 25. Statistical analysis used were Chi-square test, Mann-Whitney U-test, Spearman’s rank correlation analysis and Receiver-Operating Characteristic (ROC) curve. Results: Out of the 235 patients included, 60 patients had malignancy (overall cancer detection rate= 25.53%). The cancer detection rate for PSA ranges of (4-10) and (10-20) ng/ ml was as low as 5.95% and 13.16% respectively. Patients with malignant disease had significantly smaller prostate gland size than patients with benign disease (53.89 vs 63.06; p-value <0.05). On the other hand, cancer detection rate was 100% for PSA greater than 50ng/ml. The cancer detection rates were only upto 10% for PSA density ranges upto 0.25 ng/ml/cm3 . The Area Under the Curve (AUC) for PSA and PSAD was 0.876 and 0.884 respectively. Only one patient (0.43%) had post-biopsy complication (acute bacterial prostatitis) requiring hospital admission. Conclusion: The current serum PSA and PSAD cut offs of 4 ng/ ml and 0.15 ng/ml/cm3 need to be raised for Indian population to increase its positive predictive value. Prospective study validation of this finding is lacking.

Keywords

• cancer detection rate
• prostate cancer
• psa cut off
• psa density cut off
• psa density
• serum psa