Biproximate ellipsoid formula with transrectal ultrasound: a superior method for PSA density in gray zone prostate cancer detection.

[PURPOSE] This study aimed to enhance prostate cancer (PCa) detection in patients with prostate-specific antigen (PSA) levels within the "gray zone" (4-10 ng/mL) by comparing PSA density (PSAD) calculations derived from the traditional ellipsoid formula (TEF) and the biproximate ellipsoid formula (BPEF).

[MATERIALS AND METHODS] A total of 99 patients were enrolled. All participants underwent transrectal ultrasound (TRUS) for prostate volume estimation, followed by PSAD calculation using both the BPEF and TEF methods. The BPEF method, which incorporates well-defined anatomical landmarks, was assessed for its accuracy in prostate volume measurement and diagnostic performance for PCa compared to TEF. Inter- and intra-observer consistency were also evaluated for both approaches.

[RESULTS] Both BPEF and TEF reliably measured prostate volume, however, BPEF demonstrated superior accuracy and higher consistency in inter- and intra-observer assessments. PSAD calculated using BPEF (BPEF-PSAD) exhibited significantly greater diagnostic performance than TEF-PSAD, with an area under the curve (AUC) of 0.84. At the optimal diagnostic threshold of 0.15 ng/mL/cm³, BPEF-PSAD achieved a sensitivity of 88.89% and a specificity of 74.60%, enhancing the discrimination between PCa and benign prostatic hyperplasia (BPH). Multivariate logistic regression analysis identified BPEF-PSAD as an independent predictor of PCa.

[CONCLUSIONS] The study concluded that the BPEF method, when combined with TRUS, improves the accuracy of PSA density measurements, potentially reducing unnecessary biopsies in patients with intermediate PSA levels, particularly in cases where MRI is unavailable or contraindicated.