The Prognostic Role of Perineural Invasion for Survival in Head and Neck Squamous Cell Carcinoma: A Systematic Review and Meta-Analysis

The aim of this study was to conduct a comprehensive review of the predictive significance of PNI in HNSCC survival outcomes. A systematic search was conducted across multiple databases, and all studies published in the last decade were screened (Research Registry ID: reviewregistry1853). The included studies were assessed using the Quality in Prognosis Studies tool. Survival outcome data were extracted, combined, and presented as hazard ratios (HR) with a 95% confidence interval (CI). Totally, 74 studies encompassing 27,559 patients were analyzed and revealed a cumulative occurrent rate of 30% for PNI in HNSCC. PNI+ HNSCC patients had a worse overall survival (HR: 1.91, 95% CI: 1.71-2.13), disease-specific survival (HR: 1.79, 95% CI: 1.55-2.07), disease-free survival (HR: 1.82, 95% CI: 1.69-1.96), local recurrence (HR: 2.54, 95% CI: 1.93-3.33), locoregional recurrence (HR: 2.27, 95% CI: 1.82-2.82), locoregional relapse free survival (HR: 1.77, 95% CI: 1.28-2.45), distant metastasis (HR: 1.82, 95% CI: 1.34-2.48), and distant metastasis-free survival (HR: 2.97, 95% CI: 1.82-4.85) compared to those PNI- patients. The available evidence unequivocally establishes PNI as a critical prognostic factor for worse survival in HNSCC patients.

Perineural Invasion Is a Significant Prognostic Factor in Oral Squamous Cell Carcinoma: A Systematic Review and Meta-Analysis

(1) Objectives: This systematic review and meta-analysis aimed to summarize current evidence regarding the prognostic role of perineural invasion (PNI) in patients with oral squamous cell carcinoma (OSCC). (2) Methods: We searched Cochrane Central, ProQuest, PubMed, Scopus, Science Direct, and Web of Science, using relevant keywords to identify eligible articles. Two independent reviewers conducted two-stage screening, data extraction, and quality assessment. The risk of bias was assessed using the Newcastle-Ottawa Scale (NOS) criteria. All analyses were performed using comprehensive meta-analysis (CMA; version 3.3.070) software. (3) Results: The study included 101 published articles encompassing 26,062 patients. The pooled analyses showed that PNI was associated with significantly worse overall survival (OS; HR = 1.45, 95% CI: 1.32-1.58; p < 0.001), worse disease-specific survival (DSS; HR = 1.87, 95% CI: 1.65-2.12; p < 0.001), and worse disease-free survival (DFS; HR = 1.87, 95% CI: 1.65-2.12; p < 0.001). Similarly, both local recurrence-free survival (LRFS) and regional recurrence-free survival (RRFS) were worse in patients with PNI (HR = 2.31, 95% CI: 1.72-3.10, p < 0.001; and HR = 2.04, 95% CI: 1.51-2.74, p < 0.001), respectively. The random-effect estimate of three studies demonstrated that the presence of PNI was associated with worse failure-free survival (FFS; HR = 2.59, 95% CI: 1.12-5.98, p < 0.001). (4) Conclusions: The current evidence suggests that PNI can be used as an independent predictor of the prognosis for patients with OSCC. The presence of PNI was associated with worse OS, DFS, DSS, FFS, and with recurrence. Asian patients and patients with extra-tumoral or peripheral PNI invasion were associated with worse prognosis.

Prognostic impact of lymphovascular and perineural invasion in squamous cell carcinoma of the tongue

This study aimed to investigate the prognostic impact of lymphovascular and perineural invasions in patients with squamous cell carcinoma of the tongue who received surgery-based treatment at our institution between January 2013 and December 2020. Patients were divided into four groups based on the presence of perineural (P-/P +) and lymphovascular invasions (V-/V +): P-V-, P-V + , P + V-, and P + V + . Log-rank and Cox proportional hazard models were used to evaluate the association between perineural /lymphovascular invasion and overall survival (OS). Altogether, 127 patients were included, and 95 (74.8%), 8 (6.3%), 18 (14.2%), and 6 (4.7%) cases were classified as P-V-, P-V + , P + V-, and P + V + , respectively. Pathologic N stage (pN stage), tumor stage, histological grade, lymphovascular invasion, perineural invasion, and postoperative radiotherapy were significantly associated with OS (p < 0.05). OS was significantly different among the four groups (p < 0.05). Significant between-group differences in OS were detected for node-positive (p < 0.05) and stage III-IV (p < 0.05) cases. OS was the worst in the P + V + group. Lymphovascular and perineural invasions are independent negative prognostic factors for squamous cell carcinoma of the tongue. Patients with lymphovascular and/or perineural invasion may have significantly poorer overall survival than those without neurovascular involvement.

Pattern and localization of perineural invasion predict poor survival in oral tongue carcinoma

BACKGROUND

Survival rate for oral tongue squamous cell carcinoma (OTSCC) is still poor and, despite Tumor-Node-Metastasis staging system has been recently updated, patients included under the same stage still show difference in prognosis. Perineural invasion (PNI) emerged to be an indicator of tumor aggressive behavior and unfortunate events. In this study, we investigate the clinic and prognostic value of PNI in a cohort of OTSCC patients.

METHODS

About 200 patients with OTSCC were retrospectively evaluated the presence of PNI. PNI was furtherly descripted as uni-/multifocal and as intra-/peritumoral. Disease-Specific and Relapse-Free Survival (DSS; RFS) were estimated; moreover, we included PNI in the current AJCC 8th Staging System, improving the prognostication model.

RESULTS

Perineural invasion was found in 40.5% of patients. Intratumoral PNI predicted patients at high risk of being diagnosed with lymph-node metastasis. Tumors with positive PNI reported a worse DSS (Hazard Ratio=1.878, p-value = 0.008). Moreover, patients exhibiting both multifocal intra- and peritumoral PNI reported poorest DSS (Hazard Ratio = 2.409, p-value = 0.010). Patients were reclassified in a new staging system in case of multifocal PNI, providing better stratification capacity.

CONCLUSIONS

Perineural invasion might serve as an additional prognostic factor in OTSCC, and by integrating PNI in the staging system, further improvements in prognostication might be reached.

[Staging cancers of the oral cavity according to the 8th edition of AJCC TNM system: Issues and recommendations]

Stage of cancer at the time of the diagnosis is a key factor for the prognosis and the determination of appropriate treatment. Several cancer staging systems are used worldwide. The most useful staging system is the tumor, node and metastasis (TNM) staging system develop by the American Joint Committee on Cancer (AJCC) in collaboration with the Union for International Cancer Control (UICC) referred to as the AJCC TNM staging system. The AJCC TNM system classifies cancers by the size and extend of the primary tumor (T), involvement of regional lymph nodes (N) and the presence of distant metastases (M). AJCC and UICC periodically modify the AJCC TNM staging system according to newly acquired clinical, pathological and biological data improving understanding of cancer physiopathology. The 8th edition of AJCC TNM system is effective for cancer patients diagnosed on or after January 1, 2018. Here, we report the issues of the staging cancers of the oral cavity according to the 8th edition of AJCC TNM system. We focus on 2 new concepts defined in the 8th edition of AJCC TNM system: depth of invasion (DOI) and extranodal extension (ENE).

Subcategorization of Perineural Invasion and Its Impact on Survival in Patients with Oral Squamous Cell Carcinoma

BACKGROUND

Perineural invasion (PNI) is  recognized as a poor prognostic factor in oral squamous cell carcinoma (OSCC). However, the prognostic significance of further histologic  subcategorization of PNI is inconclusive. In this study, we determined the prognostic relevance of histologic subcategories of PNI and their correlation with the presence of other clinical and pathological parameters METHODS: This is a retrospective study of 207 homogeneously treated OSCC patients with histologically documented PNI from a single center. Univariate and multivariate survival outcomes, namely, local recurrence-free survival (LRFS), disease-free survival (DFS), and overall survival (OS) of patients with various subcategories of PNI,namely- number of foci, size of the involved nerve, extratumoral or intratumoral extent, and intraneural or perineural location-were determined.

RESULTS

Within the histologic subcategories of PNI, tongue primary and presence of lymph node metastasis correlated significantly with the number of nerves involved with PNI. Larger size of involved nerve correlated with advanced tumor stage. Number of foci, extent, and location of PNI were not prognostically significant except size of the involved nerve which showed an inverse correlation with disease outcome as involvement of larger nerves displayed better outcomes in terms of DFS and LRFS but not of OS on multivariate analysis. Addition of adjuvant chemotherapy to radiotherapy emerged as a significant predictor of improved LRFS, DFS, and OS.

CONCLUSIONS

Histologic subcategorization of PNI did not have prognostic relevance in our study. Involvement of even small nerves was associated with poor prognosis. Addition of chemoradiation was seen to improve prognosis.

Spatial and Transcriptomic Analysis of Perineural Invasion in Oral Cancer

PURPOSE

Perineural invasion (PNI), a common occurrence in oral squamous cell carcinomas, is associated with poor survival. Consequently, these tumors are treated aggressively. However, diagnostic criteria of PNI vary and its role as an independent predictor of prognosis has not been established. To address these knowledge gaps, we investigated spatial and transcriptomic profiles of PNI-positive and PNI-negative nerves.

EXPERIMENTAL DESIGN

Tissue sections from 142 patients were stained with S100 and cytokeratin antibodies. Nerves were identified in two distinct areas: tumor bulk and margin. Nerve diameter and nerve-to-tumor distance were assessed; survival analyses were performed. Spatial transcriptomic analysis of nerves at varying distances from tumor was performed with NanoString GeoMx Digital Spatial Profiler Transcriptomic Atlas.

RESULTS

PNI is an independent predictor of poor prognosis among patients with metastasis-free lymph nodes. Patients with close nerve-tumor distance have poor outcomes even if diagnosed as PNI negative using current criteria. Patients with large nerve(s) in the tumor bulk survive poorly, suggesting that even PNI-negative nerves facilitate tumor progression. Diagnostic criteria were supported by spatial transcriptomic analyses of >18,000 genes; nerves in proximity to cancer exhibit stress and growth response changes that diminish with increasing nerve-tumor distance. These findings were validated in vitro and in human tissue.

CONCLUSIONS

This is the first study in human cancer with high-throughput gene expression analysis in nerves with striking correlations between transcriptomic profile and clinical outcomes. Our work illuminates nerve-cancer interactions suggesting that cancer-induced injury modulates neuritogenesis, and supports reclassification of PNI based on nerve-tumor distance rather than current subjective criteria.

Worst Pattern of Perineural Invasion Redefines the Spatial Localization of Nerves in Oral Squamous Cell Carcinoma

As a key histopathological characteristic of tumor invasion, perineural invasion (PNI) assists tumor dissemination, whereas the current definition of PNI by dichotomy is not accurate and the prognostic value of PNI has not reached consensus. To define PNI status in each patient when mixed types of PNI occurred simultaneously, we here further subclassified the traditional PNI in 183 patients with oral squamous cell carcinoma (OSCC). The spatial localization of nerves in OSCC microenvironment was thoroughly evaluated and successfully concluded into four types of PNI: 0, tumor cells away from nerves; 1, tumor cells encircling nerves less than 33%; 2, tumor cells encircling nerves at least 33%; and 3, tumor cells infiltrating into nerve sheathes. Sequentially, patients were stratified by single and mixed types of PNI. Traditionally, types 0 and 1 were defined as PNI^-, while types 2 and 3 were PNI⁺, which predicted shorter survival time. When multiple types of PNI existed within one tumor, patients with higher score of PNI types tended to have a relatively worse prognosis. Therefore, to define the status of PNI more precisely, the new variable worst pattern of PNI (WPNI) was proposed, which was taken as the highest score of PNI types present in each patient no matter how focal. Results showed that patients with WPNI 1 had longest survival time, and WPNI 2 correlated with better overall survival (p = 0.02), local-regional recurrence-free survival (p = 0.03), and distant metastasis-free survival (p = 0.046) than WPNI 3. Multivariate Cox analysis confirmed that only WPNI 3 could independently predict patients' prognosis, which could be explained by a more damaged immune response in WPNI 3 patients with less CD3⁺CD8⁺ T cells and CD19⁺ B cells. Conclusively, WPNI by trichotomy provide more meticulous and precise pathological information for tumor-nerve interactions in OSCC patients.

Molecular and Cellular Mechanisms of Perineural Invasion in Oral Squamous Cell Carcinoma: Potential Targets for Therapeutic Intervention

Simple Summary

Squamous cell carcinoma is the most common type of oral cavity cancer. It can spread along and invade nerves in a process called perineural invasion. Perineural invasion can increase the chances of tumor recurrence and reduce survival in patients with oral cancer. Understanding how oral cancer interacts with nerves to facilitate perineural invasion is an important area of research. Targeting key events that contribute to perineural invasion in oral cavity cancer may reduce tumor recurrence and improve survival. In this review, we describe the impact of perineural invasion in oral cancer and the mechanisms that contribute to perineural invasion. Highlighting the key events of perineural invasion is important for the identification and testing of novel therapies for oral cancer with perineural invasion.

Abstract

The most common oral cavity cancer is squamous cell carcinoma (SCC), of which perineural invasion (PNI) is a significant prognostic factor associated with decreased survival and an increased rate of locoregional recurrence. In the classical theory of PNI, cancer was believed to invade nerves directly through the path of least resistance in the perineural space; however, more recent evidence suggests that PNI requires reciprocal signaling interactions between tumor cells and nerve components, particularly Schwann cells. Specifically, head and neck SCC can express neurotrophins and neurotrophin receptors that may contribute to cancer migration towards nerves, PNI, and neuritogenesis towards cancer. Through reciprocal signaling, recent studies also suggest that Schwann cells may play an important role in promoting PNI by migrating toward cancer cells, intercalating, and dispersing cancer, and facilitating cancer migration toward nerves. The interactions of neurotrophins with their high affinity receptors is a new area of interest in the development of pharmaceutical therapies for many types of cancer. In this comprehensive review, we discuss diagnosis and treatment of oral cavity SCC, how PNI affects locoregional recurrence and survival, and the impact of adjuvant therapies on tumors with PNI. We also describe the molecular and cellular mechanisms associated with PNI, including the expression of neurotrophins and their receptors, and highlight potential targets for therapeutic intervention for PNI in oral SCC.

The neuropeptide calcitonin gene-related peptide links perineural invasion with lymph node metastasis in oral squamous cell carcinoma

Objective

Although perineural invasion (PNI) is well-known to be correlated with and able to predict lymph node metastasis (LNM) in oral squamous cell carcinoma (OSCC), the clinical and molecular correlation between PNI and LNM has not been elucidated, and preoperative biomarkers for LNM prediction in OSCC are urgently needed.

Materials and methods

The correlation between PNI and LNM was retrospectively evaluated using a cohort of 218 patients diagnosed with OSCC. Candidate neuropeptides were screened based on TCGA database and verified via immunohistochemistry and Western blot analyses. ELISA was used to detect calcitonin gene-related peptide (CGRP) in patient plasma. In vitro assays were used to explore the effects of CGRP on OSCC cells.

Results

OSCC patients with PNI had a higher incidence of LNM (69.86% vs. 26.2%, P < 0.0001, n = 218). CGRP expression was upregulated in the PNI niche and in metastatic lymph nodes, and was correlated with poor overall survival of OSCC patients. Preoperative plasma CGRP levels were higher in OSCC patients (n = 70) compared to healthy donors (n = 60) (48.59 vs. 14.58 pg/ml, P < 0.0001), and were correlated with LNM (P < 0.0001) and PNI (P = 0.0002). Preoperative plasma CGRP levels alone yielded an AUC value of 0.8088 to predict LNM, and CGRP levels combined with preoperative T stage reached an AUC value of 0.8590. CGRP promoted proliferation and migration abilities of OSCC cells, which could be antagonized by either pharmacological or genetic blockade of the CGRP receptor.

Conclusions

The neuropeptide CGRP links PNI and LNM in OSCC, and preoperative plasma CGRP levels can be used to predict LNM in OSCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08998-9.

The Impact of Histopathological Features on the Prognosis of Oral Squamous Cell Carcinoma: A Comprehensive Review and Meta-Analysis

OBJECTIVE

Over many decades, studies on histopathological features have not only presented high-level evidence of contribution for treatment directions and prognosis of oral squamous cell carcinoma (OSCC) but also provided inconsistencies, making clinical application difficult. The 8th TNM staging system of OSCC has acknowledged the importance of some histopathological features, by incorporating depth of invasion (DOI) to T category and extranodal extension (ENE) to N category. The aim of this systematic review with meta-analysis is to determine the most clinically relevant histopathological features for risk assessment and treatment planning of OSCC and to elucidate gaps in the literature.

METHODS

A systematic review was conducted using PRISMA guidelines, and the eligibility criteria were based on population, exposure, comparison, outcome, and study type (PECOS). PubMed, Cochrane, Scopus, and Web of Science were searched for articles exploring the impact of histopathological features on OSCC outcomes with Cox multivariate analysis. Pooled data were subjected to an inverse variance method with random effects or fixed effect model, and the risk of bias was evaluated using quality in prognosis studies (QUIPS). Quality of evidence was assessed with the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria.

RESULTS

The study included 172 articles published from 1999 to 2021. Meta-analyses confirmed the prognostic potential of DOI, ENE, perineural invasion, lymphovascular invasion, and involvement of the surgical margins and brought promising results for the association of bone invasion, tumor thickness, and pattern of invasion with increased risk for poor survival. Although with a small number of studies, the results also revealed a clinical significance of tumor budding and tumor-stroma ratio on predicted survival of patients with OSCC. Most of the studies were considered with low or moderate risk of bias, and the certainty in evidence varied from very low to high.

CONCLUSION

Our results confirm the potential prognostic usefulness of many histopathological features and highlight the promising results of others; however, further studies are advised to apply consistent designs, filling in the literature gaps to the pertinence of histopathological markers for OSCC prognosis.

SYSTEMATIC REVIEW REGISTRATION

International Prospective Register of Systematic Reviews (PROSPERO), identifier CRD42020219630.

Lymphovascular invasion as a prognostic tool for oral squamous cell carcinoma: a comprehensive review

Oral cancer is the most common malignancy of the head and neck region, characterized by a poor prognosis. Novel prognostic markers are needed to better stratify these patients. Lymphovascular invasion (LVI) has been included in the eighth edition of the AJCC Cancer Staging Manual as an additional prognostic factor, but its influence on the recurrence risk and lymph node metastasis is relatively understudied. This is a comprehensive review of the literature on the clinical and prognostic role of LVI in oral cancer. A relevant search of the PubMed, Scopus, and Web of Science databases yielded 29 articles that satisfied the inclusion criteria. Findings indicated that LVI is an independent negative prognostic factor in oral cancer patients and appears to be associated with cervical lymph node metastasis and loco-regional recurrence. Notably, in oral tongue cancer, survival outcomes progressively worsen when LVI is associated with other adverse pathological features, especially in the early stages. Therefore, these patients could benefit from elective neck dissection and/or adjuvant therapy. The high variability of LVI prevalence hinders the comparison of literature results. Several methodological limitations were found to be present in the collected articles, including the lack of a rigorous definition for LVI, the difficult detection in routine histological section, the presence of potential confounders, the retrospective nature, and an inadequate sample size in most studies. Therefore, it is necessary to conduct prognostic studies using standardized methods to define and quantify LVI.

Impact of lymphovascular invasion in oral squamous cell carcinoma: A meta-analysis

OBJECTIVE

Lymphovascular invasion (LVI) has been reported as a predictor of prognosis in multiple cancers. The aim of this meta-analysis was to investigate the potential value of LVI as a prognostic predictor of oral squamous cell carcinoma (OSCC).

STUDY DESIGN

To identify relevant studies, PubMed, Embase, Web of Science, and Cochrane Library database were searched from inception to October 2020. All studies exploring the association of LVI with overall survival (OS), disease-specific survival (DSS), or disease-free survival (DFS) and lymph node metastasis (LNM) were identified.

RESULT

Pooled odds ratios for LNM and hazard ratios for survival were calculated using fixed effects or random effects models. Thirty-six studies involving 17,109 patients with OSCC were included and further analyzed. The results showed that positive LVI was significantly associated with LNM and worse survival in patients with OSCC. Moreover, positive LVI was correlated with LNM in patients with early stage OSCC.

CONCLUSIONS

These findings indicate that LVI may serve as a prognostic predictor for the metastasis and prognosis of OSCC and could be considered a routine pathologic examination in clinical work.

Histological features and survival in young patients with HPV-negative oral squamous cell carcinoma

OBJECTIVES

The frequency of oral squamous cell carcinoma in young adults has increased in the last decades, and there are conflicting results in literature about its prognosis in young subjects. The aim of this study was to analyse the clinical and pathological features of oral squamous cell carcinoma in a cohort of young adults in order to investigate the presence of new independent prognostic markers.

MATERIALS AND METHODS

Only HPV-negative young patients (under 40-year-old) affected by oral squamous cell carcinoma were considered in this study. Clinical and pathological data were collected. Patients were re-staged according to the 8th edition of AJCC.

RESULTS

Overall, 66 patients were considered in this study. Perineural invasion significant correlated with both 7th and 8th edition of AJCC, and lymphovascular invasion (p-value < .05). The multivariate survival analysis showed that patients with perineural invasion had a significant worse prognosis (HR = 6.384 95% C.I. 1.304-31.252; p-value = .022).

CONCLUSIONS

Perineural invasion emerged as an independent prognostic factor for disease-specific survival in young patients with oral squamous cell carcinoma. Furthermore, the evaluation of this parameter is simple, inexpensive and can be used to augment the risk stratification of oral cancer based on the 8th edition of AJCC.

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.

Multifocal perineural invasion is a better prognosticator than depth of invasion in oral squamous cell carcinoma

OBJECTIVES

Prognostic significance of perineural invasion (PNI) in oral squamous cell carcinoma (OSCC) characterized as unifocal and multifocal was compared to depth of invasion (DOI) and extranodal extension (ENE).

MATERIALS AND METHODS

Univariable and multivariable analyses of 861 consecutive patients with OSCC undergoing treatment between 1995 and 2018 were performed, with local failure (LF) and disease-specific mortality (DSS) as the primary endpoints.

RESULTS

After adjusting for other adverse histopathological factors and adjuvant therapy, multifocal PNI was associated with a greater risk of LF (P = .01) and DSS (P = 0.02) compared to DOI. The effect of multifocal PNI was comparable to the effect of nodal metastases without ENE (P = 0.02). LF and DSS were not improved by the administration of adjuvant radiotherapy within unifocal or multifocal PNI groups.

CONCLUSION

Multifocal PNI is associated with a greater risk of death in OSCC than DOI. Its effect is comparable to that of nodal metastases (without ENE).