In the present study, PSM was a significant pathological factor associated with poorer oncological outcomes, and %positive cores was an independent value predictive of PSM (multivariate p = 0.001) showing a prognostic significance (p = 0.023) in patients with prostate cancer clinically diagnosed as localized or locally advanced disease. These results suggest that %positive cores based on extended biopsies may be useful for predicting oncological outcomes. %positive cores theoretically reflects the tumor volume , and thus is a feasible index for predicting PSM. In addition, patients with multiple positive cores in the prostatic base had poorer oncological outcomes, and they more frequently had proximal/bladder-side PSM than those with a single or no positive core in the prostatic base (48.1 vs. 6.5%, respectively, p < 0.001). Several previous studies have reported that proximal-side PSM is an adverse prognostic factor , and it has also been shown that positive cores in the prostatic base are associated with a higher rate of proximal PSM , but the relevant previous studies did not perform survival analyses. The present study additionally suggested that multiple positive cores in the prostatic base with extended biopsy protocol possibly have a prognostic significance, although further studies are required to draw a conclusion.
Previous studies have reported the frequency of PNI in radical prostatectomy specimens to be between 32 and 79%. [19–21], and it was about 50% in the present study (Table 3). A few studies reported that the presence of PNI is associated with poor oncological outcomes , and our study also supported the prognostic value of PNI. The current study also suggested that biopsy Gleason score was an independent value predictive of PNI. It has been shown that PNI of prostate cancer is relevant to a tumor’s invasive capacity , while Gleason score is also involved in invasiveness of prostate cancer in relation to the expression of matrix metalloproteinases [25, 26]. A study regarding the diagnostic value of PNI in extended biopsy cores is currently underway.
Recent advances in staging modalities and surgical indications have been associated with the low prevalence of SVI in surgical outcomes, and it has been reported that the recent low prevalence of SVI makes the validation of prognostic models/nomogram difficult . SVI did not have a prognostic significance in the present study most probably due to the small number of those with SVI; the survival curves categorized with and without SVI seemingly separated (Figure 2). Additionally, the 5 patients excluded from survival analyses because of immediate inception of adjuvant androgen deprivation therapy showed SVI, and their exclusion probably contributed to the absence of statistical significance for SVI. There has been no study examining associations between these pathological conditions and the results of precisely profiled extended biopsy. When mapping/diagramming positive cores, extended biopsy may be of value to predict SVI in patients with prostate cancer clinically diagnosed as localized disease. Interestingly, the number/percentage of positive cores calculated for the standard sextant sites or laterally-directed sextant cores did not reflect SVI, whereas positive TZ and multiple positive cores in the prostatic middle were independently associated with SVI. However, positive-predictive value of TZ biopsy assessed with tumor localization in the prostatectomy specimen was 0.86, suggesting contaminations of cancer arising from the peripheral zone. Patients with a positive TZ biopsy or multiple positive cores in prostatic middle biopsy had a larger tumor size in prostatectomy specimens. With the current 14-core biopsy protocol, parameters such as positive TZ and multiple positive cores in the prostatic middle possibly reflect the tumor size, and thus are associated with SVI. To validate the significance of these observations, studies comparing various biopsy protocols are needed.
In the present study with the mentioned extended biopsy protocol, positive TZ and multiple positive cores in the prostatic middle were independently correlated with SVI (p = 0.020 and p = 0.023, respectively). Also, %positive cores was an independent factor predictive of PSM (p = 0.001), and biopsy Gleason score was independently correlated with PNI (p = 0.001). Thus, clinical factors predictive of pathological outcomes varied among SVI, PSM, and PNI; these results suggest that prevailing staging nomograms or risk-assessment scoring systems combining multiple values such as Gleason score and %positive cores are practically possible based on the pathological approach employing extended biopsy protocols [1–3]. Additionally, artificial intelligence techniques such as artificial neural networks incorporating mentioned informations obtained from extended biopsies potentially support decision-making in prostate cancer treatment .
In this study, one patient (0.8%) had pT0 disease, and the frequency was similar to those in previous reports . The present study had several limitations. The study was retrospectively designed, and the relatively small number of patients may have led to a limited statistical power. Also, the small number of locally advanced disease cases is a limitation of this type of study; surgical indication probably affected the background of the study group, as discussed elsewhere. Further follow-up studies are warranted to confirm the significance of the observations on oncological outcomes in men with localized prostate cancer.