Introduction

Active surveillance (AS) is now an accepted strategy for men with low-risk prostate cancer (PCa). A critical factor for successful AS is the best possible patient selection. However, a recent large retrospective study indicates that currently available AS criteria are limited by a high rate of misclassification. We recently collaborated with a biopsy needle manufacturer, TSK Laboratory, to develop a novel 18-G biopsy instrument based on an existing instrument (PRIMECUT® II), by extending the side-notch length from 19 to 25 mm and the stroke length from 22 to 28 mm, to take a longer tissue core and to reach the anterior portion of the prostate. In this study, we evaluated utility of the novel biopsy instrument in the selection of patients for AS._x000D_

Methods

A total of 167 PCa patients diagnosed with the long-notch needle (n=62; long-notch group) or normal-notch needle (n=105; normal-notch group), who subsequently underwent prostatectomy, were retrospectively analyzed. All patients were diagnosed with 12 transrectal ultrasound-guided standard cores. The sampled core length, correlation between total tumor length in biopsy specimens, and total tumor volume in prostatectomy specimens were compared between the two groups. Gleason score (GS) upgrading was also compared. Prostatectomy specimens of patients who met the criteria of the PRIAS study were compared for the two groups._x000D_

Results

The mean length of tissue taken with the long-notch needle was significantly longer than that taken with the normal-notch needle (16.3 vs. 22.4 mm, p<0.001). The correlation coefficient between total tumor length in biopsy specimens and total tumor volume in prostatectomy specimens of the long-notch group was higher (r=0.701) than that in the normal-notch group (r=0.611). GS upgrading in the long-notch group was significantly lower than that in the normal-notch group (25.8 vs. 41.0%, p=0.0479) Only 1 patient with tumor volume >0.5 cc and GS 4+3 or more was included among the 5 who met the criteria of the PRIAS study in the long-notch group, while 6 patients were included among the 10 who met the criteria in the normal-notch group._x000D_

Conclusions

We developed a novel biopsy instrument with a 25 mm side-notch for longer tissue samples, increased correlation between tumor volume in biopsy and prostatectomy specimens, and decreased GS upgrading. These results suggested the utility of the long-notch needle in the selection of patients for AS.

Funding

none