Trans rectal ultra sound guided prostate biopsies: a single centre experience in Sri Lanka

Abstract

Background Trans rectal ultrasound guided prostate biopsy (TRUS) was introduced to Sri Lanka in 2002.

Objectives 1. To study clinicopathological features of males subjected to TRUS biopsy 2. To compare estimation of tumour burden by two methods in carcinoma prostate (CaP).

Methods 749 symptomatic males subjected to TRUS biopsy over 64 months at a single centre. Information was retrieved from case records. Tumour burden in CaP was calculated as: 1. Calculated tumour burden (CTB) - total percentage tumour in each core/total number of cores 2. Percentage positive biopsy cores (PPBC) - number of positive cores / total number of cores X 100. SPSS 15.0, student's t test and Spearman's rank correlation coefficients were used for statistical analysis.

Results 35.2% had CaP, microacinar in type. 34.88% were poorly differentiated. CaP was frequent among older patients (P < 0.00001). The prostate volume in CaP was significantly lower than in the benign group (P < 0.05). Prostate specific antigen (PSA) level was significantly higher in CaP (P < 0.00001). A 99.6% sensitivity and 4.7% specificity was observed at PSA of 4ng/ml for detecting CaP. Specificity was 98% at 25.5ng/ml, with a sensitivity of 44.4%. CTB and PPBC had similar correlations with biochemical/histological parameters of CaP and were strongly correlated (0.786).

Interpretation Males with CaP were older, had higher PSA levels and smaller prostates. A cut off level of PSA >4ng/ml could be used for directing symptomatic patients for TRUS biopsy to detect CaP, keeping in mind that specificity is 98% only at 25.5ng/ml. Both CTB and PPBC could be used to calculate tumour burden in TRUS with CaP.