Computerized quantification and planimetry of prostatic capsular nerves in relation to adjacent prostate cancer foci

The Role of Perineural Invasion in Prostate Cancer and Its Prognostic Significance

Simple Summary

Prostate cancer is one of the most frequently diagnosed cancers in men worldwide. Perineural invasion (PNI), the movement of cancer cells along nerves, is a commonly observed approach to tumor spread and is important in both research and clinical practice of prostate cancer. However, despite many studies reporting on molecules and pathways involved in PNI, understanding its clinical relevance remains insufficient. In this review, we aim to summarize the current knowledge of mechanisms and prognostic significance of PNI in prostate cancer, which may provide new perspectives for future studies and improved treatment.

Abstract

Perineural invasion (PNI) is a common indication of tumor metastasis that can be detected in multiple malignancies, including prostate cancer. In the development of PNI, tumor cells closely interact with the nerve components in the tumor microenvironment and create the perineural niche, which provides a supportive surrounding for their survival and invasion and benefits the nerve cells. Various transcription factors, cytokines, chemokines, and their related signaling pathways have been reported to be important in the progress of PNI. Nevertheless, the current understanding of the molecular mechanism of PNI is still very limited. Clinically, PNI is commonly associated with adverse clinicopathological parameters and poor outcomes for prostate cancer patients. However, whether PNI could act as an independent prognostic predictor remains controversial among studies due to inconsistent research aim and endpoint, sample type, statistical methods, and, most importantly, the definition and inclusion criteria. In this review, we provide a summary and comparison of the prognostic significance of PNI in prostate cancer based on existing literature and propose that a more standardized description of PNI would be helpful for a better understanding of its clinical relevance.

Objective quantification of nerves in immunohistochemistry specimens of thyroid cancer utilising deep learning

Accurate quantification of nerves in cancer specimens is important to understand cancer behaviour. Typically, nerves are manually detected and counted in digitised images of thin tissue sections from excised tumours using immunohistochemistry. However the images are of a large size with nerves having substantial variation in morphology that renders accurate and objective quantification difficult using existing manual and automated counting techniques. Manual counting is precise, but time-consuming, susceptible to inconsistency and has a high rate of false negatives. Existing automated techniques using digitised tissue sections and colour filters are sensitive, however, have a high rate of false positives. In this paper we develop a new automated nerve detection approach, based on a deep learning model with an augmented classification structure. This approach involves pre-processing to extract the image patches for the deep learning model, followed by pixel-level nerve detection utilising the proposed deep learning model. Outcomes assessed were a) sensitivity of the model in detecting manually identified nerves (expert annotations), and b) the precision of additional model-detected nerves. The proposed deep learning model based approach results in a sensitivity of 89% and a precision of 75%. The code and pre-trained model are publicly available at https://github.com/IA92/Automated_Nerves_Quantification.

The study of nerves as a prognostic marker for cancer is becoming increasingly important. However, accurate quantification of nerves in cancer specimens is difficult to achieve due to limitations in the existing manual and automated quantification methods. Manual quantification is time-consuming and subject to bias, whilst automated quantification, in general, has a high rate of false detections that makes it somewhat unreliable. In this paper, we propose an automated nerve quantification approach based on a novel deep learning model structure for objective nerve quantification in immunohistochemistry specimens of thyroid cancer. We evaluate the performance of the proposed approach by comparing it with existing manual and automated quantification methods. We show that our proposed approach is superior to the existing manual and automated quantification methods. The proposed approach is shown to have a high precision as well as being able to detect a significant number of nerves not detected by the experts in manual counting.

Quantification of perineural invasion focus after radical prostatectomy could improve predictive power of recurrence

Perineural invasion (PNI) after radical prostatectomy (RP) is a common feature of prostate cancer (PCa) and has been associated with unfavorable tumor characteristics. However, its prognostic relevance is controversial. In this study, we evaluated the impact of both PNI status (PNI+ versus PNI-) and quantified number of PNI focus on the long-term prognosis of biochemical recurrence (BCR) after RP. After reevaluating PNI of a total of 721 patients with localized PCa who underwent RP at our institution between 2000 and 2002, we examined associations between PNI status or PNI focus number and clinicopathological factors including tumor stage, Gleason score, margin status, tumor location, preoperative prostate specific antigen, age, prostate weight as well as BCR outcome. PNI was present in 530 of 721 cases (73.5%) of the RP specimens and was associated with more aggressive disease. BCR occurred in 19.4% of all patients within a median follow-up period of 8.5 years. PNI+ status was associated with poor BCR prognosis in univariate analysis but lost in multivariate analysis. Based on the number of PNI focus, PNI was further divided into 2 distinct group: PNI+ a (≤3) and PNI+ b (>3). In a multivariate Cox regression model, PNI+ b (>3) was identified as an independent BCR prognostic factor. Quantification of PNI focus number beside the dichotomized status recording will not only provide more detailed information but also be a novel prognostic indicator for risk stratification. Further external validation will be needed for an optimal cut-off value of the PNI focus number. Our findings will help further research on the relevance of PNI in the pretreatment setting and support ongoing efforts to understand its role of cancer progression.

Innervation of papillary thyroid cancer and its association with extra-thyroidal invasion

Nerves are emerging regulators of cancer progression and in several malignancies innervation of the tumour microenvironment is associated with tumour aggressiveness. However, the innervation of thyroid cancer is unclear. Here, we investigated the presence of nerves in thyroid cancers and the potential associations with clinicopathological parameters. Nerves were detected by immunohistochemistry using the pan-neuronal marker PGP9.5 in whole-slide sections of papillary thyroid cancer (PTC) (n = 75), compared to follicular thyroid cancer (FTC) (n = 13), and benign thyroid tissues (n = 26). Nerves were detected in most normal thyroid tissues and thyroid cancers, but nerve density was increased in PTC (12 nerves/cm² [IQR 7–21]) compared to benign thyroid (6 nerves/cm² [IQR: 3–10]) (p = 0.001). In contrast, no increase in nerve density was observed in FTC. In multivariate analysis, nerve density correlated positively with extrathyroidal invasion (p < 0.001), and inversely with tumour size (p < 0.001). The majority of nerves were adrenergic, although cholinergic and peptidergic innervation was detected. Perineural invasion was present in 35% of PTC, and was independently associated with extrathyroidal invasion (p = 0.008). This is the first report of infiltration of nerves into the tumour microenvironment of thyroid cancer and its association with tumour aggressiveness. The role of nerves in thyroid cancer pathogenesis should be further investigated.

Tumour innervation and neurosignalling in prostate cancer

Prostate cancer progression has been shown to be dependent on the development of autonomic nerves into the tumour microenvironment. Sympathetic nerves activate adrenergic neurosignalling that is necessary in early stages of tumour progression and for initiating an angiogenic switch, whereas parasympathetic nerves activate cholinergic neurosignalling resulting in tumour dissemination and metastasis. The innervation of prostate cancer seems to be initiated by neurotrophic growth factors, such as the precursor to nerve growth factor secreted by tumour cells, and the contribution of brain-derived neural progenitor cells has also been reported. Current experimental, epidemiological and clinical evidence shows the stimulatory effect of tumour innervation and neurosignalling in prostate cancer. Using nerves and neurosignalling could have value in the management of prostate cancer by predicting aggressive disease, treating localized disease through denervation and relieving cancer-associated pain in bone metastases.

Impact of biopsy perineural invasion on the outcomes of patients who underwent radical prostatectomy: a systematic review and meta-analysis

Objectives: To investigate the association between biopsy perineural invasion (PNI) and oncological outcomes of prostate cancer (PCa) after radical prostatectomy (RP).Materials and methods: A systematic literature search was performed using PubMed, EMBASE and Web of Science up to December 2018 to identify the eligible studies that included localized PCa patients who underwent biopsy and subsequently RP as well as follow-up information. Meta-analyses were conducted using available hazard ratios (HRs) of biopsy PNI from both univariate and multivariate analyses.Results: Eighteen studies including 14,855 patients with treatment follow-up information were included in the current systematic review. The rate of biopsy PNI varied between 7.0% and 33.0%. Seven out of the 18 studies that demonstrated biopsy PNI were associated with adverse pathologic features. Thirteen out of the 18 studies showed biopsy PNI correlated significantly with higher rates of biochemical recurrence (BCR)/cancer progression status or worse prognostic outcomes. With pooled data based on four studies with available univariate analysis results and four studies with multivariate analysis, statistically significant associations were found between biopsy PNI and BCR with univariate analysis (HR = 2.05; 95% CI = 1.57-2.68; p < 0.001) and with multivariate analysis (HR = 1.57; 95% CI = 1.28-1.93; p < 0.001).Conclusion: Evidence from the included observational studies indicated that biopsy PNI was not only correlated with adverse pathologic characteristics but also with worse BCR prognosis of local PCa after RP. The status of biopsy PNI could serve as a promising risk-stratification factor to help the decision-making process, considering active surveillance (AS) or further treatment for PCa patients.

Tumor Neurobiology and the War of Nerves in Cancer

Nerves are emerging regulators of cancer progression. Cancer cells induce the outgrowth of nerves in the tumor microenvironment through the release of neurotrophic factors, and in return nerves liberate neurotransmitters that activate cancer growth and dissemination. Although sympathetic nerves drive tumor angiogenesis via the liberation of noradrenaline, sensory and parasympathetic nerves stimulate cancer stem cells. Interestingly, recent evidence indicates that parasympathetic nerves can eventually inhibit tumor progression, suggesting a yin-yang type of regulation of cancer by nerves. From a broader perspective, the question of a higher level of control of cancer development by the central nervous system should be raised. SIGNIFICANCE: Nerves are emerging regulators of cancer initiation, progression, and metastasis. Here, we review the evidence to date and explore the basic and clinical ramifications of these findings.

Quantitative perineural invasion is a prognostic marker in prostate cancer

This study aimed to investigate the prognostic value of a quantitative, detailed, yet practical analysis of perineural invasion in radical prostatectomy specimens in a high-risk prostate cancer cohort. A total of 114 patients with prostate cancer who underwent radical prostatectomy between 2000 and 2013 were analysed. Using S100 protein immunohistochemistry assisted in the detection of nerves. In the area of closest proximity of the tumour to the dorso-lateral margins, nerves were counted and the infiltration of nerves was categorised (0-3). Category 0 was nerves without immediate tumour-cell-contact. All nerves being fully surrounded by tumour (classical perineural carcinosis) were categorised group 3. Two further categories discriminated between nerves that were touched either by carcinoma cells below 50% of the circumference (category 1) or above (category 2). Perineural carcinosis (Pn1) was seen in 61.4% of cases and correlated positively with ISUP grades, pT categories and presence of intraductal carcinoma but failed significance on Kaplan-Meier analysis. A more quantitative analysis of percentual perineural involvement did demonstrate significant survival differences: cases with less than one Pn1-positive nerve in 5 high power fields had longer survival times. Incomplete perineural involvement (category 1-2) did not have a prognostic value, endorsing the current definition of perineural carcinosis as full circumferential encasement of a nerve by tumour cells. A quantitative analysis of the percentage of nerves positive for perineural invasion has a higher prognostic value than the classical dichotomous statement on the mere presence of perineural invasion.

Diminished long-term recovery of peak flow rate (PFR) after robotic prostatectomy in men with baseline PFR <10 mL/s and incidental association with high-risk prostate cancer

OBJECTIVE

The aim of this study was to evaluate the effects of robot-assisted radical prostatectomy (RARP) on uroflowmetry (UF) parameters among men with baseline peak flow rates (PFR) <10 mL/s.

METHODS

A single-surgeon RARP database of 1082 men who underwent prospective UF testing was analyzed. Men filled out International Prostate Symptom Score questionnaires and underwent uroflowmetry and post-void bladder ultrasound before surgery and at each follow-up visit. Patients were divided into 2 groups based on preoperative PFR: those with PFR <10 mL/s (n = 158) and those with PFR ≥10 mL/s (n = 924). Univariate and multivariate regression models tested the association of preoperative characteristics in predicting postoperative PFR improvement. Within the PFR <10 mL/s group, preoperative variables were analyzed to predict pathologic outcomes.

RESULTS

Three months after RARP, men with baseline PFR <10 mL/s had a 3-fold improvement in PFR (from mean of 7.0 to 24.2 mL/s), whereas in men with PFR ≥10 mL/s there was a 50% improvement (from mean of 19.7 to 28.9 mL/s; P < .001). Improvement in PFR remained stable for >5 years, but mean postoperative PFR was 20% lower in men with baseline PFR <10 mL/s. Preoperative prostate-specific antigen (odds ratio [OR] 0.75; 95% confidence interval [CI] 0.59-0.95) and PFR (OR 0.52; 95% CI 0.34-0.80) were independent predictors of the percentage improvement in men with baseline PFR <10 mL/s. Preoperative PFR ≤7 mL/s was an independent predictor of Gleason score ≥8 (P = .016), seminal vesicle invasion (P = .010), and lymph node invasion (0.029).

CONCLUSIONS

After RARP, PFR improved significantly, with the improvement persisting over long-term follow-up. However, men with baseline PFR <10 mL/s had a 20% lower postoperative PFR over 5 years, suggesting permanent damage to the bladder and the need for early treatment to maintain bladder health. There appears to be an association between baseline PFR ≤7 mL/s and adverse pathologic features.

The impact of multifocal perineural invasion on biochemical recurrence and timing of adjuvant androgen-deprivation therapy in high-risk prostate cancer following radical prostatectomy

BACKGROUND

Perineural invasion (PNI) is a distinct pathologic entity and a recognized source of tumor spread. However, the role of PNI in high-risk prostate cancer (PCa) has not been explored. The aims of the study were to investigate the impact of PNI on biochemical recurrence (BCR) and optimal timing of adjuvant androgen-deprivation therapy (ADT) after radical prostatectomy (RP).

METHODS

A total of 265 prostatectomies, median follow-up 45 months, were assessed for the presence and intensity of PNI (unifocal and multifocal) in RP specimens. Kaplan-Meier curves were used to estimate BCR probabilities. Cox proportional hazard models were used to address predictors of BCR. Harrell's C-index was conducted to further validate prognostic value of multi-PNI.

RESULTS

A total of 123 patients (46.4%) were PNI positive, among which, 91 (74%) and 32 (26%) had unifocal PNI (uni-PNI) and multifocal PNI (multi-PNI), respectively. The presence of multi-PNI was strongly associated with increasing incidence of BCR (HR = 3.87, 95%CI: 1.66-9.01, P = 0.002). Patients with uni-PNI had a similar BCR rate to those without PNI after adjuvant ADT. For men with multi-PNI, immediate ADT was superior to delayed ADT in decreasing biochemical failure.

CONCLUSIONS

Our findings suggest that detection of multi-PNI in high-risk RP specimens could be a prognosticator for early biochemical relapse post-surgery. Initiation of adjuvant therapy may be appropriate in patients with multi-PNI as soon as possible after surgery.

Perineural Invasion and Risk of Lethal Prostate Cancer

Background: Prostate cancer has a propensity to invade and grow along nerves, a phenomenon called perineural invasion (PNI). Recent studies suggest that the presence of PNI in prostate cancer has been associated with cancer aggressiveness.Methods: We investigated the association between PNI and lethal prostate cancer in untreated and treated prostate cancer cohorts: the Swedish Watchful Waiting Cohort of 615 men who underwent watchful waiting, and the U.S. Health Professionals Follow-Up Study of 849 men treated with radical prostatectomy. One pathologist performed a standardized histopathologic review assessing PNI and Gleason grade. Patients were followed from diagnosis until metastasis or death.Results: The prevalence of PNI was 7% and 44% in the untreated and treated cohorts, respectively. PNI was more common in high Gleason grade tumors in both cohorts. PNI was associated with enhanced tumor angiogenesis, but not tumor proliferation or apoptosis. In the Swedish study, PNI was associated with lethal prostate cancer [OR 7.4; 95% confidence interval (CI), 3.6-16.6; P < 0.001]. A positive, although not statistically significant, association persisted after adjustment for age, Gleason grade, and tumor volume (OR 1.9; 95% CI, 0.8-5.1; P = 0.17). In the U.S. study, PNI predicted lethal prostate cancer independent of clinical factors (HR 1.8; 95% CI, 1.0, 3.3; P =0.04).Conclusions: These data support the hypothesis that perineural invasion creates a microenvironment that promotes cancer aggressiveness.Impact: Our findings suggest that PNI should be a standardized component of histopathologic review, and highlights a mechanism underlying prostate cancer metastasis. Cancer Epidemiol Biomarkers Prev; 26(5); 719-26. ©2017 AACR.

Urinary nerve growth factor as an oncologic biomarker for prostate cancer aggressiveness

OBJECTIVES

We investigated urinary nerve growth factor (NGF) as a novel urinary biomarker for high-grade prostate cancer (PCa).

METHODS AND MATERIALS

After institutional review board approval for a prospective pilot study, we enrolled men at the preoperative visit before robotic-assisted radical prostatectomy. Demographics, urinary flow parameters, and urine samples were collected. Urinary NGF and urinary creatinine were obtained in the translational science laboratory. Pathologic and postoperative demographics were collected after surgery. NGF is the primary outcome variable (dependent variable). The pathologic Gleason score (ordinal variable ≤6, 7, and ≤8) served as an independent grouping variable. Multivariate analysis using a general linear model was conducted to investigate associations between independent variables and NGF (dependent variable) after adjusting for urinary concentration and volume.

RESULTS

We enrolled and analyzed urine samples and pathologic data from 115 subjects. Patient pathology included 24% (n = 28) Gleason score 6 or less, 68% (n = 78) Gleason score 7, and 8% (n = 9) Gleason score 8 or greater. Perineural invasion was more prevalent in higher-grade disease (P<0.001). The median NGF level was 24.1 pg/ml (range: 0.16-270.5 pg/ml) and was transformed to the log base 10 scale. Total bladder volume, urinary creatinine level, prostate-specific antigen level, and diabetes were correlated with the Log NGF. In a general linear model, adjusting for bladder volume and urinary creatinine, increasing Log10 NGF was associated with higher Gleason score (Gleason category ≤6, 7, and ≥8; P = 0.003).

CONCLUSIONS

Urinary NGF may be a biomarker for higher-grade PCa. Our pilot study suggests further investigation is warranted to determine whether urinary NGF could provide unique additional information in patients with PCa.