The highest incidence of PCa is reported in Australia/New Zealand, Northern & Western Europe and North America (79.8-111.6 per 1,00,000 population)3. In Africa (10.6–61.7 per 1,00,000 population), the southern African nations have higher incidence of PCa than north African nations, with highest incidence reported in Nigeria3. Among Asian countries (4.5–10.5 per 1,00,000 population), the incidence varies with lowest rates being in Iran and highest rates in Philippines3, with India falling in-between the two extremes4. The incidence of PCa in India has been reported to be ranging between 2 and 11.1 per 1,00,000 population in various population-based cancer registries all over India5.
Our study shows low positive predictive value for PCa in the grey zone range (4–10) ng/mL of serum PSA. Our study proves that patients can be counselled and reassured regarding higher probability of benign outcome at serum PSA range (4–10) ng/mL.
Major studies conducted in India analysed the PSA levels between grey zone and PSA levels above 10 ng/mL. Agnihotri et al., had an overall cancer detection rate of 34.6% and for serum PSA ranges of (4–10) was 15.2% irrespective of DRE findings6. They had suggested raising the serum PSA cut off in symptomatic men with negative DRE for TRUS biopsy in India to 5.4 ng/mL to avoid 10% unnecessary biopsies. Agarwal et al., had a overall cancer detection rate of 34.6 % with 28.3 % detection rate in the grey zone levels. They suggested an increased sensitivity and specificity of biopsy yield for a cut off of 6 ng/mL7. Chavan et al., had an overall cancer detection rate of 8.7% with 2.3% detection rate in the grey zone levels. Furthermore, they suggested raising the cut-off level to 20 ng/mL in Indian population for biopsy9. These reports reflect the low cancer detection rates of TRUS biopsy in grey zone PSA levels in Indian population which correlates with our study. In our study we have further stratified the grey zone levels into 4 categories and analysed each category statistically.
Many studies from other countries all over Asia have reported wide variations in the TRUS biopsy yield. Yu et al., from Taiwan a cancer detection rate of 14.6% in patients with serum PSA between (4.1–20) ng/mL 9. Narayanaswamy et al., from Kuwait reported lower yield for serum PSA ranges of (4–10) and (10–20) ng/mL 10.
A large retrospective study from China by Na R et al., reported lower yield for patients with serum PSA less than 10 ng/mL and (10–20) ng/mL despite overall high yield11. Two studies from Singapore by Lee et al., and Teo et al., confirmed the lower yield for serum PSA below 10 ng/mL which was less than 21% 12,13. In contrast to other Asian studies, the study by Lee et al., reported higher yield of 38.4% for serum PSA range of (10–20) ng/mL 12. Another large study by Teoh et al., from Hong Kong reported lower yield for symptomatic men with normal DRE with serum PSA below 20 ng/mL (22%)14. Two studies from Japan by Miyoshi et al., and Imazu et al., were the only studies from Asia showing much higher TRUS biopsy yield in contrast to all other Asian studies 15,16.
The European studies showed much higher yield of TRUS biopsy as compared to Asian studies. Two studies from North America showed high TRUS biopsy yield more than 35%. The largest study was reported by Orozco et al., from the Unites States, showing higher overall yield despite performing 6-core biopsies17.
Hence, other than few exceptions, Asian population (including India) have a lower TRUS biopsy yield as compared to other continents, especially for serum PSA values less than 20 ng/mL. Our study has confirmed the above findings. Hence the traditional serum PSA cut off of 4 ng/mL followed in western countries gives lower TRUS biopsy yield for Indian population. The current cut offs for PSA have high sensitivity and low specificity. Hence adjusting or raising the serum PSA cut offs for Indian population can increase the TRUS biopsy yield without increasing the false negative rate, thus avoiding unnecessary biopsies. Our study has a very low rate of post-biopsy complications requiring admission indicating that the procedure is safe if performed with accurate technique under antibiotic cover.