Invasion characteristics of oral tongue cancer: frequency of reporting and effect on survival in a population-based study

Predicting survival in patients with buccal cancer: A study based on SEER database and external validation in China

OBJECTIVE

Buccal mucosa cancer (BMC) is one of the most common oral cancers and has poor prognosis. The study aimed to develop and validate nomograms for predicting the 1-, 3-, and 5-year overall survival (OS) and cancer-specific survival (CSS) of BMC patients.

METHODS

We collected and reviewed information on BMC patients diagnosed between 2004 and 2019 from the Surveillance Epidemiology and End Results database. Two nomograms were developed and validated to predict the OS and CSS based on predictors identified by univariate and multivariate Cox regression. An extra external validation was further performed using data from Sun Yat-sen Memorial Hospital (SYSMH).

RESULTS

A total of 3154 BMC patients included in this study were randomly assigned to training and validation groups in a 2:1 ratio. Independent prognostic predictors were identified, confirmed, and fitted into nomograms for OS and CSS, respectively. The C-indices are 0.767 (Training group OS), 0.801 (Training group CSS), 0.763 (Validation group OS), and 0.781 (Validation group OS), respectively. Moreover, the nomograms exhibited remarkable precision in forecasting and significant clinical significance, as evidenced by receiver operating characteristic (ROC) curves, calibration curves, and decision curve analyses (DCA). The final validation using our data from SYSMH also showed high accuracy and substantial clinical benefits within the nomograms. The C-indices are 0.849 (SYSMH group OS) and 0.916 (SYSMH group CSS). These indexes are better than tumor, node, and metastasis stage based on prediction results.

CONCLUSIONS

The nomograms developed with great performance predicted 1-, 3-, and 5-year OS and CSS of BMC patients. Use of the nomograms in clinical practices shall bring significant benefits to BMC patients.

Prognostic factors in surgically treated tongue squamous cell carcinoma in stage T1-2N0-1M0: A retrospective analysis

PURPOSE

The study aimed to retrospectively identify the prognostic factors of surgically treated primary tongue squamous cell carcinoma (TSCC) cases and assess the benefits of surgical neck lymph node dissection (LND) in early-stage cancer.

METHODS

Patients with primary TSCC with pT1-2N0-1M0 stage without distant metastasis who were treated with surgery during 2014-2016 at Xiangya Hospital, Central South University were included. Univariate and multivariate Cox models were constructed to explore prognostic factors of overall survival (OS), disease-free survival (DFS), and local recurrence-free survival (LRFS). Sub-group analysis was used to assess the effect of adjuvant therapy and the prognostic value of LND for the early-stage patients.

RESULTS

In total, 440 patients met the inclusion criteria. During the follow-up period, the 5-year OS, DFS, were 84.4% and 70.0%, respectively. Univariate analysis showed that TNM stage, lymphovascular invasion (LVI), and/or perineural invasion (PNI), pathological differentiation, etc. were significant predictors of OS and DFS. Multivariate analysis showed that TNM stage and the degree of pathological differentiation were independent prognostic factors for all outcomes. Besides, the number of cervical LND could independently predict both DFS and LRFS while LVI/PNI were associated with DFS. And high-quality neck LND (≥30) significantly improved DFS and LRFS for patients of pT1cN0M0 or stage I as compared to those without LND.

CONCLUSIONS

TNM stage and pathological differentiation were crucial prognostic factors for postoperative patients with TSCC. Notably, high-quality cervical LND was beneficial for the improvement of DFS and LRFS for patients of pT1cN0M0 or stage I.

Does lymphovascular invasion predict survival in oral cancer? A population-based analysis

OBJECTIVE

To evaluate lymphovascular invasion as an independent predictor for overall survival in patients with oral cavity squamous cell carcinoma.

STUDY DESIGN

Retrospective cohort study.

SETTING

Multi-center, population-based facilities reporting to the National Cancer Database registry.

METHODS

The database was accessed to collect data on patients with oral cavity squamous cell carcinoma. A multivariate cox proportional hazards model was used to analyze the association between presence of lymphovascular invasion and overall survival.

RESULTS

16,992 patients met inclusion criteria. 3,457 patients had lymphovascular invasion. The mean follow-up was 32 ± 19 months. Lymphovascular invasion predicted reduced 2-year overall survival (relative hazard 1.29, 95% CI: 1.20, 1.38, p < 0.001) and 5-year overall survival (relative hazard 1.30, 95% CI: 1.23, 1.39, p < 0.001). LVI reduced overall survival in patients with squamous cell carcinoma of the oral tongue (HR: 1.27, 95% CI: 1.17, 1.39, p < 0.001), floor of mouth (HR: 1.33, 95% CI: 1.17, 1.52, p < 0.001) and buccal mucosa (HR: 1.44, 95% CI: 1.15, 1.81, p = 0.001). Patients with lymphovascular invasion treated with surgery plus post-operative radiotherapy had significantly improved survival compared to those who underwent surgery alone (relative hazard 1.79, 95% CI: 1.58, 2.03, p < 0.001), and patients treated with surgery + post-operative chemoradiotherapy had improved survival compared to those treated with surgery alone (relative hazard 2.0, 95% CI: 2.26, 1.79, p < 0.001).

CONCLUSION

Lymphovascular invasion is an important independent risk factor for decreased overall survival in oral cavity squamous cell carcinoma involving the oral tongue, floor of mouth and buccal mucosa subsites.

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.

Peri-Neural Invasion Is an Important Prognostic Factor of T2N0 Oral Cancer

Background and objectives: Among patients with pathologically proven T2N0 oral squamous cell carcinoma (OSCC), a notable amount of patients still die from tumor recurrence although they have radical surgery for early stage cancers. In literature, the prognostic indicators of this specific disease entity were rarely reported. This study aims at analyzing the prognostic factors of T2N0 OSCC patients and discussing possible managements to improve the survival.

MATERIALS AND METHODS

From January 2012 to December 2017, the data of 166 pathologically proven T2N0 oral cancer patients proved by radical surgery were retrospectively collected. The clinical and pathologic factors including age, gender, tumor differentiation grade, perineural invasion (PNI), angiolymphatic invasion (ALI), margin status, and adjuvant therapy were analyzed by univariate and multivariate analysis to determine their association with disease-specific survival (DSS), and disease-free survival (DFS), which were calculated by Kaplan-Meier method.

RESULTS

After median follow up time of 43.5 months, overall 3-year rates of DSS and DFS were 86.1% and 80.1% respectively for our 166 patients. Univariate analysis showed that the 3-year DSS of 90.8% for PNI negative patients was significantly better than DSS of 57.0% for PNI positive patients (p = 0.0006). The 3-year DFS of 84.2% for PNI negative patients was also significantly better than DFS of 54.6% for PNI positive patients (p = 0.001). Further multivariate analysis revealed PNI was the only independent prognostic factor associated with both DSS (Hazard Ratio (HR) = 5.02; 95% Confidence Interval (CI) = 1.99-12.6; p = 0.001), and DFS (HR = 3.92; 95% CI = 1.65-9.32; p = 0.002). Nearly 10% (16) of the 166 patients had adverse pathologic feature of PNI only. In the 11 patients without adjuvant therapy, 5 patients died from OSCC. No patients had recurrence or mortality after they received adjuvant therapy with chemotherapy ± radiotherapy.

CONCLUSION

PNI was an independent prognostic factor for T2N0 oral cancer patients. Adjuvant chemotherapy and radiotherapy may benefit the survival of this specific disease entity, but further investigations are needed to elucidate the optimal regimen.

Prognostic Value of Perineural Invasion in Oral Tongue Squamous Cell Carcinoma: A Systematic Review and Meta-Analysis

OBJECTIVES

A significant number of recently published research has outlined the contribution of perineural invasion (PNI) to clinical outcomes in oral tongue squamous cell carcinoma (OTSCC), but some results remain conflicting. This study aimed to determine whether patients with OTSCC with PNI have a worse prognosis than those without PNI.

MATERIALS AND METHODS

PubMed, Embase, and the Cochrane Library were queried for potentially eligible articles published up to December 2020. The primary outcomes were the hazard ratio (HR) for locoregional recurrence, overall survival (OS), disease-free survival (DFS), and cancer-specific survival (CSS). The random-effect model was used in all analyses.

RESULTS

Seventeen studies (4445 patients) were included. Using adjusted HRs, the presence of PNI was associated with a higher risk of locoregional recurrence (HR=1.73, 95%CI: 1.07-2.79, P=0.025, I2 = 33.1%, Pheterogeneity=0.224), worse OS (HR=1.94, 95%CI: 1.39-2.72, P<0.001, I2 = 0.0%, Pheterogeneity=0.838), worse DFS (HR=2.13, 95%CI: 1.53-2.96, P<0.001, I2 = 48.4%, Pheterogeneity=0.071), and worse CSS (HR=1.93, 95%CI: 1.40-2.65, P<0.001, I2 = 25.5%, Pheterogeneity=0.251). PNI had an impact on locoregional recurrence in early-stage OTSCC but not in all stages, and on OS, DFS, and CSS in all-stage and early-stage OTSCC. The sensitivity analyses showed that the results were robust.

CONCLUSION

The presence of PNI significantly affects the locoregional recurrence and survival outcomes among patients with OTSCC.

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.

Elective Neck Dissection, but Not Adjuvant Radiation Therapy, Improves Survival in Stage I and II Oral Tongue Cancer with Depth of Invasion >4 mm

Purpose/objective(s)

In early-stage, node negative oral tongue cancer, there is limited data supporting tumor depth of invasion (DOI) as an indication for post-operative radiotherapy (PORT) to the primary site. The primary aim of this study is to examine the effect of tumor DOI and PORT on overall survival (OS).

Materials and methods

The National Cancer Database (NCDB) was used to query patients with AJCC stage I and II oral tongue cancer (2006-2013). Patients were stratified by receipt of PORT, elective neck dissection (ND), and DOI (≤4 mm or >4 mm). Kaplan-Meier analysis was performed to compare OS (using the log-rank test) between PORT versus no-PORT. Multivariable Cox proportional hazards regression model performed to evaluate the independent effect of PORT and neck dissection on OS.

Results

Among 939 patients, 69.3% were clinical stage I, 67.4% received ND, 23.4% had DOI >4 mm, and 10.4% received PORT. The addition of PORT did not improve OS with tumor DOI ≤4 mm (p = 0.634) or >4 mm (p = 0.816). The addition of elective neck dissection improved OS for DOI >4 mm (p = 0.010), but not for ≤4 mm (p = 0.128). On multivariable analysis, ND improved OS if DOI >4 mm (HR, 0.37; 95% CI, 0.17-0.81 [p = .012]), when also controlling for age, sex, PORT status, clinical stage, and pathological stage.

Conclusion

Tumor DOI should not be used as a sole indication for PORT in early stage oral tongue cancers. Elective neck dissection at the time of excision of the primary tumor results in higher OS for tumors with DOI >4 mm.

Nerve-tumour interaction enhances the aggressiveness of oral squamous cell carcinoma

OBJECTIVES

Perineural invasion (PNI) is a poor prognostic pathologic feature of oral squamous cell carcinoma (OSCC). The mechanisms of PNI remain poorly understood, and nerve-tumour interactions have been implicated for its pathogenesis.

DESIGN AND SETTING

Systematic investigation of nerve-tumour interactions was performed using fresh human peripheral nerve. In vitro and in vivo models were used to determine the ability of human peripheral nerves to enhance OSCC migration/invasion. Retrospective cohort study was also carried out in one medical centre from 2001 to 2009.

PARTICIPANTS

314 T1-2 OSCC patients.

MAIN OUTCOME MEASURES

In the transwell migration/invasion assay, the cells in five representative fields were counted. In the nerve implantation model, tumour size was estimated. PNI quantification by PNI focus number was carried out in the OSCC patients to correlate with cervical lymph node metastasis and oncologic outcomes.

RESULTS

The transwell migration/invasion assay demonstrated that human peripheral nerves, compared with subcutaneous soft tissue, significantly enhanced the migration/invasion abilities of OSCC. Moreover, the enhanced migration was dose-dependent with increased length or number of peripheral nerve segments. The nerve implantation model showed that human peripheral nerve also enhanced OSCC growth in vivo. Finally, increased PNI focus number was found dose-dependently associated with increased cervical lymph node metastasis and decreased 5-year disease-specific survival rates.

CONCLUSIONS

These results clearly indicated the presence of nerve-tumour interaction that involved paracrine influences leading to aggressiveness of OSCC. Further investigations are required to explore key cell types and molecules involved in nerve-tumour interactions for future therapeutic targeting of PNI in OSCC.

p75 Nerve Growth Factor Receptor as a Specific Nerve Marker in the Diagnosis of Perineural Invasion of Squamous Cell Carcinoma

OBJECTIVES

Perineural invasion (PNI) is an important factor in tumor prognosis. We evaluated p75 nerve growth factor receptor (p75NGFR) as a neuromarker for perineural invasion of squamous cell carcinoma.

METHODS

A comparison of H&E, and S100 and p75NGFR immunohistochemical staining methods, using sequential sections from 29 samples, for identification nerve bundles and PNI diagnosis, was carried out.

RESULTS

p75NGFR and S100 correctly identified more nerve bundles than H&E. Accuracy of p75NGFR was higher than that of S100, but there was no significant difference from H&E. The accuracy of nerve bundle identification by p75NGFR and S100 showed no significant difference among different histopathologic grades of squamous cell carcinomas. p75NGFR gave mild staining of small vessels, while S100 gave strong staining of smooth muscle and glandular tissue.

CONCLUSIONS

p75NGFR specifically stains nerve tissue and is better than S100 and H&E in identifying nerve bundles. p75NGFR is expected to become a new neuromarker.

Discrete Perineural Invasion Focus Number in Quantification for T1-T2 Oral Squamous Cell Carcinoma

Objective

Perineural invasion (PNI) has been an established poor prognostic feature for T1-T2 oral squamous cell carcinoma (OSCC). Different presentations and amounts of PNI are commonly observed, but PNI is currently recorded as being present or absent. This study asked whether the quantification of PNI provides additional information for early OSCC.

Study Design

Retrospective cohort study.

Setting

Tertiary referral medical center.

Subjects and Methods

Pathologic reevaluations were performed for 314 patients with T1-T2 OSCC who underwent curative surgery from June 2001 to August 2009. A novel parameter, PNI focus number, was defined for PNI quantification. With 5 PNI foci as the cutoff, patients were categorized into 3 groups: no PNI (0 PNI foci), low PNI (PNI foci, 1-5), and high PNI (PNI foci >5). Rate of cervical lymph node metastasis (LN+), 5-year disease-specific survival (DSS), and 5-year overall survival (OS) were analyzed among these groups.

Results

PNI focus number independently predicted for LN+, poor DSS, and poor OS in multivariate analysis after controlling for T classification, lymphovascular invasion, differentiation, margin, and tumor thickness. The 5-year DSS demonstrated a dose-dependent decrease among the 3 groups (no PNI, 88.6%; low PNI, 75.2%; high PNI, 33.8%; P < .001). Moreover, the 5-year DSS of the high PNI group was significantly worse than that of the low PNI group.

Conclusion

PNI focus number can be a novel parameter for PNI quantification in early OSCC. Although optimal quantification methods still require further investigation, this study offers clear clinical support for the nerve-tumor interaction hypothesis and advocates further mechanistic research for the exploration of PNI-related treatment concepts for OSCC.

Overexpression of Translocation Associated Membrane Protein 2 Leading to Cancer-Associated Matrix Metalloproteinase Activation as a Putative Metastatic Factor for Human Oral Cancer

Translocation associated membrane protein 2 (TRAM2) has been characterized as a component of the translocon that is a gated channel at the endoplasmic reticulum (ER) membrane. TRAM2 is expressed in a wide variety of human organs. To date, no information is available regarding TRAM2 function in the genesis of human cancer. The purpose of this study was to investigate the status of the TRAM2 gene in oral squamous cell carcinoma (OSCC) cells and clinical OSCC samples. Using real-time quantitative reverse transcriptase-polymerase chain reaction, Western blotting analysis, and immunohistochemistry, we detected accelerated TRAM2 mRNA and protein expression levels both in OSCC-derived cell lines and primary tumors. Moreover, TRAM2-positive OSCC tissues were correlated closely (P<0.05) with metastasis to regional lymph nodes and vascular invasiveness. Of note, knockdown of TRAM2 inhibited metastatic phenotypes, including siTRAM2 cellular migration, invasiveness, and transendothelial migration activities with a significant (P<0.05) decrease in protein kinase RNA(PKR) - like ER kinase (PERK) and matrix metalloproteinases (MMPs) (MT1-MMP, MMP2, and MMP9). Taken together, our results suggested that TRAM2 might play a pivotal role in OSCC cellular metastasis by controlling major MMPs. This molecule might be a putative therapeutic target for OSCC.

The role of perineural invasion in treatment decisions for oral cancer patients: A review of the literature

PURPOSE

The role of perineural invasion (PNI) in the management of patients with oral squamous cell carcinoma (OSSC) is still controversial, and there is no consensus regarding the most appropriate therapeutic approach. The purpose of this study is to review the findings in the literature describing OSCC as a neurotropic malignancy, with the aim of correlating perineural invasion with treatment decisions and disease prognosis.

MATERIALS AND METHODS

A literature search was conducted of references based on the MEDLINE and Cochrane Database of Systematic Reviews, with subject keywords including four main categories: perineural invasion, perineural spread, oral squamous cell cancinoma, neurotropic carcinoma.

RESULTS

In this systematic review and analysis, more than 350 publications met the eligibility criteria of the authors.

CONCLUSION

Perineural invasion (PNI) is a widely recognized indicator of poor prognosis in oral cancer patients, strongly correlating with aggressive tumor behavior, disease recurrence, and increased morbidity and mortality. Elective neck dissection could be an indicator in improving neck control in PNI-positive patients, while the addition of adjuvant postoperative radiotherapy may not significantly improve survival rates. Various molecular markers have been correlated with perineural tumor spread, but further investigations are required before targeting PNI as part of advanced cancer therapies.

Triple-positive pathologic findings in oral cavity cancer are related to a dismal prognosis

OBJECTIVES/HYPOTHESIS

Perineural invasion (PNI), lymphovascular invasion (LVI), and extracapsular spread (ECS) of lymph nodes are adverse histopathologic factors among patients with oral cancer. We analyzed the clinical impact of the combination of PNI, LVI, and ECS among patients with oral cancer.

STUDY DESIGN

Retrospective analysis of patients with oral cancer that was treated primarily with surgery with at least 5 years of follow-up data in a tertiary referral center.

METHODS

In total, 554 patients diagnosed with oral cavity squamous cell carcinoma who underwent operations consecutively between 2006 and 2008 in our hospital were enrolled. Clinical characteristics, 5-year survival rates, and local/regional control rates were analyzed.

RESULTS

There were 41 females and 513 males. Patients with PNI, LVI, or ECS presented pathologically had 5-year overall survival rates of 58.4%, 50.4%, and 31.4%, respectively. Patients with both ECS and PNI or both ECS and LVI presented had 5-year overall survival rates of 31.5% and 22.2%, respectively. Patients presenting with triple-positive status (PNI, LVI, and ECS) had only a 20.0% 5-year overall survival rate. The 5-year local/regional control rate for patients with both ECS and PNI or both ECS and LVI was 26% and 44.4%, respectively; for all three factors, it was 26.7%.

CONCLUSION

Patients with triple-positive status (PNI, LVI, ECS), ECS and PNI, or ECS and LVI experienced very low 5-year local/regional control rates, 5-year overall, and disease-specific survival rates. Novel interventions are necessary to improve these clinical outcomes.

LEVEL OF EVIDENCE

4.

Human papillomavirus in carcinomas of the tongue: clinical and prognostic implications

It is not clear whether the presence of human papillomavirus (HPV) in squamous cell carcinomas of the tongue (SCCT) is of etiopathogenic and clinical significance. This study was designed to establish the incidence of HPV in SCCT and to determine the influence of HPV detection on clinical parameters and the prognosis. Clinical and histopathological data of 64 patients with SCCT were collected. Thirty benign lesions of the tongue were analyzed in parallel, in order to compare the HPV incidence and genotypes in these lesions with those of SCCT. Paraffin blocks of all cases were collected and PCR was carried out using SPF10 primers and the INNO-LiPA genotyping methodology. HPV was detected in 26.2% of the patients. Hybridization results showed that all patients except one had high-risk (HR)-HPV. HPV56 was the most common (42.1%), followed by HPV18 (26.3%), HPV16 (10.5%), HPV66 (10.5%), HPV39 (5.3%), and HPV51 (5.3%). The odds ratio of HR-HPV infection in cases vs. controls was statistically significant (9.45, 95% confidence interval 1.18-75.46). Among the results of the univariate analysis correlating the presence of HR-HPV with different clinical parameters, only mortality showed a statistically significant correlation, being higher in HR-HPV patients (odds ratio 3.97, 95% confidence interval 1.07-14.7).

Perineural invasion in T1 oral squamous cell carcinoma indicates the need for aggressive elective neck dissection

Observation or elective neck dissection (END) for cN0 neck remains controversial for the treatment of T1-2 oral squamous cell carcinoma (OSCC). Perineural invasion (PNI) has been recognized as a poor prognostic factor for OSCC. However, its significance in T1 OSCC remains unclear. A detailed histologic reevaluation of PNI was carried out in 307 patients with T1-2 OSCC who received surgical treatment between June 2001 and January 2009. We found that the presence of PNI correlated with cervical lymph node metastasis in both T1 and T2 OSCC, with a lower PNI-positive rate in T1 (17.1% vs. 36.6%; P<0.001). Importantly, observation for cN0 neck was used twice as often in T1 than in T2 patients (47.4% vs. 22.8%; P<0.001). Although patients with T1 OSCC achieved significantly better outcomes, PNI correlated with neck recurrence and poor disease-specific survival (DSS) only in T1 (P<0.001 and P<0.0001) but not in T2 patients (P=0.399 and 0.1478). Of the 146 patients with T1 OSCC, PNI independently predicted cervical lymph node metastasis, neck recurrence, and poor DSS. END significantly reduced neck recurrence of T1 OSCC in PNI-positive (P=0.001) but not in PNI-negative (P=0.114) patients. In addition, END improved the 5-year DSS of T1 OSCC more in PNI-positive than in PNI-negative patients (16.2% vs. 5.4%). Our results indicate that PNI independently predicts a poor prognosis in T1 OSCC patients who are potentially curable but tend to be treated conservatively. For its efficacy in improving treatment outcomes, aggressive END is indicated for T1 OSCC patients at the presence of PNI.

Perineural invasion as a major determinant for the aggressiveness associated with increased tumor thickness in t1-2 oral tongue and buccal squamous cell carcinoma

BACKGROUND

Neck management for cN0 neck remains controversial for T1-2 oral tongue and buccal squamous cell carcinoma (SCC). Increased tumor thickness and perineural invasion (PNI) are two pathologic features that correlated with cervical lymph node (LN) metastasis and poor survival. However, the relationships between these two features remain unclear.

METHODS

Detailed histologic reevaluation under hematoxylin and eosin staining was performed in tumors of 212 consecutive patients with T1-2, cN0 oral tongue and buccal SCC. The interrelationships between the impacts of tumor thickness and PNI on cervical LN metastasis and disease-specific survival (DSS) were analyzed.

RESULTS

Increased tumor thickness (>6 mm) correlated with higher LN metastasis and poor 5-year DSS rates in univariate analysis. However, only PNI independently predicted both in multivariate analysis (P = 0.004 and P = 0.039, respectively). When stratified by PNI status, increased tumor thickness did not correlate with higher LN metastasis rate in either PNI-negative or PNI-positive groups (P = 0.337 and P = 0.730). Compared to patients with thin tumors (≤6 mm), patient with thick tumors revealed significantly higher LN metastasis rate (41.9 vs. 16.4 %, P = 0.001) and lower 5-year DSS rate (77.5 vs. 93.7 %, P = 0.006) only at the presence of PNI.

CONCLUSIONS

PNI can be a major determinant for higher LN metastasis and poor 5-year DSS rates associated with increased tumor thickness in T1-2 oral tongue and buccal SCC. Careful evaluation of PNI should be mandatory in routine pathologic examination, aside from the measurement of tumor thickness.

Transcriptional repression of DLEC1 associates with the depth of tumor invasion in oral squamous cell carcinoma

The objective of this study was to clarify the expression and epigenetic regulation of DLEC1, a candidate tumor suppressor gene (TSG) located at 3p21.3-p22, in oral squamous cell carcinoma (OSCC) and the clinical relevance of its down-expression. Quantitative RT-PCR was performed to exam the expression level of DLEC1 in matched OSCC and normal oral samples from 57 prospectively enrolled patients (with additional matched leukoplakia samples from 9 patients). We defined DLEC1 down-expression as a 2-fold decrease in expression of DLEC1 between normal tissues and tumors, and determined its correlation with clinical characteristics. Methylation-specific PCR (MSP) and bisulfite sequencing were used to evaluate the promoter methylation status of DLEC1 in 19 OSCC, 19 oral leukoplakia (OL), and 17 normal oral tissues. A statistically significant association between DLEC1 down-expression and invasive depth of OSCC was observed (P=0.026). Besides, expression of DLEC1 decreased sequentially from normal tissues to OL and then to OSCC (P<0.05), which was inversely correlated with methylation status of the DLEC1 promoter. Promoter methylation of DLEC1 increased progressively among normal tissues, OL, and OSCC, as revealed by MSP, and confirmed by sequencing. Treatment of OSCC cell lines with 5-aza-2'-deoxycytidine (5-Aza-dC) reversed the methylation and restored DLEC1 expression. Our results demonstrating that down-expression and promoter methylation of DLEC1 increased from normal tissues to premalignancies and then to malignancies. Furthermore, its transcriptional repression is associated with the depth of tumor invasion.

Clinical, pathological and molecular determinants in squamous cell carcinoma of the oral cavity

Squamous cell carcinoma of the oral cavity (OCSCC) is the most frequently observed form of head-and-neck cancer in Southeast Asia and is the sixth most common cancer worldwide. Most cases of this preventable disease are caused by alcohol consumption, smoking and betel nut chewing. The survival rates of patients with advanced OCSCC have not increased significantly in recent years. While treatments for OCSCC are similar worldwide, survival rates differ by geographical area. The various genetic profiles and individual genetic susceptibility for carcinogens may account for this discrepancy. In some respects, molecular alteration or accumulation affects tumor progression and the clinical outcomes among patients with OCSCC. Clarifying the tumor behavior of oral cancer, with regard to pathological features or molecular aspects, could help clinicians to judge, tailor and adopt more effective therapeutic strategies to treat oral cancer.