Risk factors associated with positive surgical margins following radical prostatectomy for clinically localized prostate cancer: Can nerve-sparing surgery increase the risk?

Evaluation of Oncological Outcomes and Data Quality in Studies Assessing Nerve-sparing Versus Non-Nerve-sparing Radical Prostatectomy in Nonmetastatic Prostate Cancer: A Systematic Review

CONTEXT

Surgical techniques aimed at preserving the neurovascular bundles during radical prostatectomy (RP) have been proposed to improve functional outcomes. However, it remains unclear if nerve-sparing (NS) surgery adversely affects oncological metrics.

OBJECTIVE

To explore the oncological safety of NS versus non-NS (NNS) surgery and to identify factors affecting the oncological outcomes of NS surgery.

EVIDENCE ACQUISITION

Relevant databases were searched for English language articles published between January 1, 1990 and May 8, 2020. Comparative studies for patients with nonmetastatic prostate cancer (PCa) treated with primary RP were included. NS and NNS techniques were compared. The main outcomes were side-specific positive surgical margins (ssPSM) and biochemical recurrence (BCR). Risk of bias (RoB) and confounding assessments were performed.

EVIDENCE SYNTHESIS

Out of 1573 articles identified, 18 studies recruiting a total of 21 654 patients were included. The overall RoB and confounding were high across all domains. The most common selection criteria for NS RP identified were characteristic of low-risk disease, including low core-biopsy involvement. Seven studies evaluated the link with ssPSM and showed an increase in ssPSM after adjustment for side-specific confounders, with the relative risk for NS RP ranging from 1.50 to 1.53. Thirteen papers assessing BCR showed no difference in outcomes with at least 12 mo of follow-up. Lack of data prevented any subgroup analysis for potentially important variables. The definitions of NS were heterogeneous and poorly described in most studies.

CONCLUSIONS

Current data revealed an association between NS surgery and an increase in the risk of ssPSM. This did not translate into a negative impact on BCR, although follow-up was short and many men harbored low-risk PCa. There are significant knowledge gaps in terms of how various patient, disease, and surgical factors affect outcomes. Adequately powered and well-designed prospective trials and cohort studies accounting for these issues with long-term follow-up are recommended.

PATIENT SUMMARY

Neurovascular bundles (NVBs) are structures containing nerves and blood vessels. The NVBs close to the prostate are responsible for erections. We reviewed the literature to determine if a technique to preserve the NVBs during removal of the prostate causes worse cancer outcomes. We found that NVB preservation was poorly defined but, if applied, was associated with a higher risk of cancer at the margins of the tissue removed, even in patients with low-risk prostate cancer. The long-term importance of this finding for patients is unclear. More data are needed to provide recommendations.

Obesity leads to a higher rate of positive surgical margins in the context of robot-assisted radical prostatectomy. Results of a prospective multicenter study

Introduction

Current results concerning the effect of body mass index (BMI) on positive surgical margins (PSMs) after robot-assisted radical prostatectomy (RARP) in patients with localized prostate cancer are inconsistent. Therefore, the aim of this study was to further analyse the association between BMI and PSMs after RARP.

Material and methods

Between March 2017 and December 2017 a multicentre, prospective, randomised, single-blind series with a blinded outcome assessment of 232 RARP patients was performed. Multivariate logistical regression models were used to analyse the independent effect of obesity, with body-mass-index (BMI) dichotomised at 30 kg/m² (model-1) and at 90^th percentile (model-2), on PSMs.

Results

Median BMI was 27.2 kg/m², PSMs were found in 15.5% (n = 36). In multivariate model-1, obesity did not have a significant effect on PSMs (OR 2.34, p = 0.061). However, if BMI was dichotomized at the 90^th percentile (BMI ≥33.7 kg/m²), patients with a higher BMI showed PSMs four-times more frequently (OR 3.99, p = 0.013). In both models, preoperative prostate-specific antigen (PSA) levels and pathological tumour stage had a significant effect on PSMs. There was no significant correlation between BMI and the extent of PSMs, nor a significant difference between the BMI groups and the localisation of PSMs. There was a higher percentage of posteriolateral PSM localisation in obese patients compared to patients with a BMI of less than 30 kg/m² (58.3% and 25.3% of the localisations were posterolateral in obese and non-obese patients, respectively), however this effect was not statistically significant (p = 0.175).

Conclusions

In addition to a longer operation time and about twice as many complications, patients with a BMI of ≥33.7 kg/m² had a higher PSM rate after RARP. Differences in localization of PSMs in relation to obesity should be evaluated in future research.

"Real-time" Assessment of Surgical Margins During Radical Prostatectomy: State-of-the-Art

Histopathologic examination of the pathologic specimens using hematoxylin & eosin stains represents the backbone of the modern pathology. It is time-consuming; thus, "real-time" assessment of prostatic and periprostatic tissue has gained special interest in the diagnosis and management of prostate cancer. The current study focuses on the review of the different available techniques for "real-time" evaluation of surgical margins during radical prostatectomy (RP). We performed a comprehensive search of the Medline database to identify all the articles discussing "real-time" or intraoperative assessment of surgical margins during RP. Several filters were applied to the search to include only English articles performed on human subjects and published between January 2000 and March 2019. The search revealed several options for pathologic assessment of surgical margins including intraoperative frozen sections, confocal laser endomicroscopy, optical spectroscopy, photodynamic diagnosis, optical coherence tomography, multiphoton microscopy, structured illumination microscopy, 3D augmented reality, and ex vivo fluorescence confocal microscope. Frozen section represents the gold standard technique for real-time pathologic examinations of surgical margins during RP; however, several other options showed promising results in the initial clinical trials, and considering the rapid development in the field of molecular and cellular imaging, some of these options may serve as an alternative to frozen section.

Level of invasion into fibromuscular band is an independent factor for positive surgical margin and biochemical recurrence in men with organ confined prostate cancer

Background

This study aimed investigate the effect of the level of invasion into fibromuscular band (FMB) of prostate on the positive surgical margin (PSM) and biochemical recurrence (BCR) after radical prostatectomy (RP) in patients with organ-confined (pT2) prostate cancer.

Methods

The clinical and pathological data of 461 consecutive patients with pT2 prostate cancer were evaluated regarding the level of invasion into FMB. The relationship between levels of invasion into FMB and PSM / BCR was assessed.

Results

The rate of PSM at an FMB level of at 2 was 18.8%, which was significantly greater than the rates at levels 0 (5.4%) and 1 (7.8%). The level of FMB (p = 0.007) and percentage of tumor volume (p = 0.012) were identified as independent factors predictive of a positive surgical margin in a multivariate analysis. The 5-year BCR-free survival rates for a level 0–1 FMB with negative surgical margin, level 0–1 FMB with positive surgical margin, level 2 FMB with negative surgical margin, and level 2 FMB with positive surgical margin were 96.6%, 86.4%, 85.6%, and 72.9%, respectively (p <  0.001). A level 2 FMB (p = 0.050), positive surgical margin (p = 0.001), and surgical Gleason score (p = 0.001) were identified as independent predictors of a BCR of pT2 prostate cancer.

Conclusions

Among patients with negative surgical margins, the surgical Gleason score and level of FMB independently affected the incidence of a BCR of pT2 prostate cancer. The level of FMB was an independent predictor of both a positive surgical margin and a BCR of pT2 disease. Accordingly, the level of FMB might help to further stratify the prognosis of patients with pT2 disease.

Ex vivo peripheral nerve detection of rats by spontaneous Raman spectroscopy

Nerve-sparing surgery is increasingly being applied to avoid functional deficits of the limbs and organs following surgery. Peripheral nerves that should be preserved are, however, sometimes misidentified due to similarity of shape and color to non-nerve tissues. To avoid misidentification of peripheral nerves, development of an in situ nerve detection method is desired. In this study, we report the label-free detection of ex vivo peripheral nerves of Wistar rats by using Raman spectroscopy. We obtained Raman spectra of peripheral nerves (myelinated and unmyelinated nerves) and their adjacent tissues of Wistar rats without any treatment such as fixation and/or staining. For the identification of tissue species and further analysis of spectral features, we proposed a principal component regression-based discriminant analysis with representative Raman spectra of peripheral nerves and their adjacent tissues. Our prediction model selectively detected myelinated nerves and unmyelinated nerves of Wistar rats with respective sensitivities of 95.5% and 88.3% and specificities of 99.4% and 93.5%. Furthermore, important spectral features for the identification of tissue species were revealed by detailed analysis of principal components of representative Raman spectra of tissues. Our proposed approach may provide a unique and powerful tool for peripheral nerve detection for nerve-sparing surgery in the future.

Safe-R: a novel score, accounting for oncological safe nerve-sparing at radical prostatectomy for localized prostate cancer

OBJECTIVES

The objectives of the study were to describe a novel score (safe-R), combining information on surgical margin status (SM) and extend of nerve-sparing (NS) applicable for all patients undergoing radical prostatectomy (RP), and to test the impact of our frozen-section navigated nerve-sparing approach (NeuroSAFE) on safe-R score.

METHODS

We retrospectively analyzed 9,635 RPs performed at our center between 2002 and 2011. Of these, 47 % were conducted with NeuroSAFE. Proportions of NS and SM status were assessed. Subsequently, a score for oncological safe NS (safe-R) was developed; Safe-R was categorized as 3 (for negative SM and bilateral NS), 2 (for negative SM and unilateral NS), 1 (for negative SM without NS), and 0 (for patients with positive SM), respectively. The impact of NeuroSAFE on safe-R was analyzed by chi-square test and confirmed by multinomial logistic regression, adjusting for preoperative risk factors.

RESULTS

Applying NeuroSAFE resulted in enhanced safe-R score, indicating lower rates of positive SM and higher rates of NS, across all risk categories (all p < 0.001). For example in high-risk patients, NeuroSAFE resulted in lower proportions of safe-R 0 (27.6 vs. 33.6 %) and higher proportions of safe-R 3 (32.4 vs. 17.1 %, p < 0.001). Linkage between the NeuroSAFE approach and safe-R was confirmed after multinomial logistic adjustment for preoperative risk factors. All results were confirmed in a propensity-matched cohort (matched for preoperative risk factors and year of surgery, data not shown).

CONCLUSION

Safe-R represents a novel tool to assess and report on oncological safe nerve-sparing in RP. NeuroSAFE is associated with enhanced safe-R scores.