Is the diagnostic yield of prostate needle biopsies affected by prostate volume?

Objectives: To determine the effect of prostate volume on the diagnostic yield of prostate biopsies. Materials and methods: 155 consecutive patients underwent 12-core transrectal ultrasound guided needle biopsies. Data were collected prospectively on age, serum PSA, digital rectal examination (DRE), previous prostate biopsies, prostate volume and pathologic result. Univariate and multivariate logistic regressions were undertaken to determine the effect of prostate volume on the risk for a positive biopsy. Results: 45 patients (29%) were diagnosed with cancer. The median patient age was 63 (range 48-82) years, the median PSA level was 6.7 ng/ml (0.5-156 ng/ml), and the median prostate volume was 57 ml (16-273 ml). 42 patients (27%) had an abnormal DRE and 51 (33%) had undergone previous prostate biopsies. Positive biopsy rates were 39%, 33%, and 14% for prostate volume below 46 ml, between 45 and 73 ml, and above 72 ml, respectively. Univariate analysis showed that age, serum PSA, DRE and prostate volume were all associated with a positive biopsy. Multivariate analysis adjusted for age, PSA and DRE showed a significant risk increase for a positive biopsy in smaller prostates. (OR = 5.6 95% CI 1.75-17.89; and 8.86 95% CI 2.72-28.82, for prostate volume between 45 and 72 ml and below 45 ml, respectively). Conclusion: The diagnostic yield of prostate biopsies is significantly lower in large prostates. As the result the standard 12-core biopsy may be insufficient for the diagnosis of cancer in large prostates.