Nelson Neal Stone

Purpose: To investigate a novel prostate biopsy device capable of taking specimens between 1.5 and 5.5 cm in length and to determine the distances from apex to base in men undergoing transperineal biopsy. Materials and Methods: An actuator was developed capable of firing an 18-gauge true-cut biopsy needle with a specimen notch of 5.5 cm adjustable at 1 mm between 1.5 and 5.5 cm. The length of specimens retrieved vs the notch length was determined using fresh porcine kidneys and compared with a Bard device. The distance from prostate apex to base was determined in men undergoing transperineal biopsy using a proprietary software program. The program determined apex to base lengths throughout the gland. The number of needles required to span the prostate between ≤ 2.0 cm to > 5.0 cm was also determined. Results: The variable length device outperformed the Bard device at different lengths collecting an average of 88% vs 82% of the notch length (n = 576, P < .001). The mean biopsy needle length required for an average prostate volume of 48.2 cc was 3.4 cm. 79.6% of the biopsies taken with the Bard device would not have reached that distance. The new needle collected 5.8 mm ³ of tissue vs 3.8 mm ³ (1.5 times more) for the Bard device. Conclusions: The variable length biopsy device can sample the prostate to 5.5 cm in length with an average of 88% of the specimen collected. Eighty percent of men would need a biopsy needle longer than what is typically used in clinical practice.

Objectives: The objective of this study is to propose a novel method of determining the nadir PSA (nPSA) for men with prostate cancer treated by partial gland ablation (PGA).Materials and Methods: Two cohorts of men were analyzed to develop a formula for the nPSA in men undergoing PGA. First, 123 men with a suspicion of prostate cancer underwent transperineal mapping biopsy (TPMB) and found to have benign pathology. Their prostate‐specific antigen (PSA) was compared to the prostate volume using curve estimation regression analysis. Second, the contribution of PSA from an ablated region was determined by using a surrogate of 545 men who had whole‐gland brachytherapy followed by prostate biopsy. Biopsy results were compared to radiation dose (calculated as the biological equivalent dose) levels in men who were free from biochemical failure. The nPSA was then calculated by using the PSA density (PSAD) for the untreated volume plus the PSA from the post‐brachytherapy patients.Results: The PSAD with the highest R² (0.80, p < 0.001) for the 123 men who had TPMB and a negative biopsy was 0.12 ng/mL². In the brachytherapy patients, five 20 Gy dose groups were analyzed from ≤140 to ≥220 Gy, which demonstrated a progressive decrease in the positive biopsy rate to 1.5% at the highest dose (p = 0.036). PSA was 2.Conclusion: A method for determining the nPSA following PGA using brachytherapy was developed. The formula relies on complete ablation of the treated volume, which resulted in no PSA contribution from that component. Other forms of ablative energy should yield similar results. Further clinical validation of this concept is warranted.