Association between pathological invasion patterns and late lymph node metastases in patients with surgically treated clinical No early oral tongue carcinoma

Enhancing oral squamous cell carcinoma prediction: the prognostic power of the worst pattern of invasion and the limited impact of molecular resection margins

Objective

Oral squamous cell carcinoma (OSCC) originates from the mucosal lining of the oral cavity. Almost half of newly diagnosed cases are classified as advanced stage IV disease, which makes resection difficult. In this study, we investigated the pathological features and mutation profiles of tumor margins in OSCC.

Methods

We performed hierarchical clustering of principal components to identify distinct patterns of tumor growth and their association with patient prognosis. We also used next-generation sequencing to analyze somatic mutations in tumor and marginal tissue samples.

Results

Our analyses uncovered that the grade of worst pattern of invasion (WPOI) is strongly associated with depth of invasion and patient survival in multivariable analysis. Mutations were primarily detected in the DNA isolated from tumors, but several mutations were also identified in marginal tissue. In total, we uncovered 29 mutated genes, mainly tumor suppressor genes involved in DNA repair including BRCA genes; however none of these mutations significantly correlated with a higher chance of relapse in our medium-size cohort. Some resection margins that appeared histologically normal harbored tumorigenic mutations in TP53 and CDKN2A genes.

Conclusion

Even histologically normal margins may contain molecular alterations that are not detectable by conventional histopathological methods, but NCCN classification system still outperforms other methods in the prediction of the probability of disease relapse.

Tumor Budding Should Be in Oral Cavity Cancer Reporting: A Retrospective Cohort Study Based on Tumor Microenvironment

The utility of histological grading, which is useful in predicting prognosis in many tumors, is controversial for oral squamous cell carcinoma (OSCC). Therefore, new histopathological parameters should be added to histopathology reports of OSCCs. The study aimed to evaluate the parameters of worst invasion pattern (WPOI) and tumor budding in patients with OSCC, to compare them with other histopathological parameters, clinical data and overall survival, and to evaluate these results within the literature. A total of 73 OSCC cases with excisional biopsies were included in this study. WPOI, tumor budding, cell nest size, tumor-stroma ratio, stromal lymphocyte infiltration and stroma type, as well as classical histopathological parameters, were evaluated on hematoxylin-eosin-stained sections. Perineural invasion, lymph node metastases, advanced stage, presence of more than five buds and single cell invasion pattern in univariate survival analyses are characterized by a shortened overall survival time. While there was no significant difference between WPOI results and survival in the survival analysis, WPOI 5 was associated with more frequent lymph node metastasis and advanced stage at the time of diagnosis compared to WPOI 4. We concluded that tumor budding and single-cell invasion should be considered prognostic histopathologic parameters in OSCC.

Histological risk score and its role in predicting recurrence in early-stage oral squamous cell carcinomas

Context

Oral squamous cell carcinoma (OSCC) comprises more than 90% of oral cancers and is the most common carcinoma affecting the oral cavity. Early stage T1/T2 OSCC have a heterogeneous prognosis and a significant number of patients develop loco regional recurrence (LRR) and have reduced disease free survival (DFS) with increased disease related mortality.

Aims and Objectives

To assess the impact of the three parameters used in Brandwein-Gensler risk model along with lympho-vascular invasion (LVI), depth of invasion (DOI) and lymph node metastases in predicting LRR in early stage OSCC.

Materials and Methods

This was a retrospective study on early stage T1/2 OSCC patients over a period of 2 years who received treatment by surgical resection and had follow-up data. LRR was assessed based on recurrence of OSCC at the initial site or in regional lymph nodes.

Results

Out of 1135 OSCC cases during our study period a total of 207 cases befitted our inclusion criteria. Recurrence was noted in 113 (54.6%) cases. Univariate analysis identified LVI (P < 0.00001), DOI (P < 0.00001), nodal involvement (P < 0.00001), worst pattern of invasion (WPOI) (P < 0.00001), lymphocytic host response (LHR) (P = 0.004), perineural invasion (PNI) (P = 0.012) as strong statistically significant risk factors for LRR.

Conclusion

Adequate assessment of simple parameters on routine H and E by incorporating Brandwein-Gensler histological risk scoring model at the initial presentation can help prognosticate and predict LRR and select patients for post-surgical adjuvant therapy.

Worst Pattern of Invasion as an Independent Predictor of Lymph node Metastasis and Prognosis in oral Cavity Squamous cell carcinoma - A Retrospective Cohort Study

Although Worst pattern of invasion (WPOI) is one of the histopathological (HP) markers that has been utilized in risk stratification of oral squamous cell carcinoma (OSCC) patients, its potential as an independent predictive factor for lymph node metastasis (LNM) and prognosis is least analyzed. Aim of the study is to analyze the relationship of various HP parameters to WPOI, their propensity for lymph node metastasis and prognostic value. This retrospective study included 140 patients diagnosed with resectable OSCC who underwent definitive surgery. Multiparametric HP risk assessment was done on the postoperative specimen and patients were categorized as low-risk WPOI (Type 1-3), and high-risk group (type 4 and 5). After categorization, 36.1% patients had low-risk WPOI and 63.9% had high-risk WPOI. Significant association was noted between WPOI and patient's age (p = 0.001), nodal stage (p = 0.001), lymphovascular invasion (LVI) (p = 0.006) and neural invasion (p = 0.001). 87% patients with nodal metastasis had high risk WPOI. LVI (p = 0.014) and WPOI (p < 0.001) had significant predictive role in LNM. High-risk WPOI and bone involvement were found to be predictive factors for overall survival, and only high risk WPOI had strong correlation with disease free survival having significant poor prognosis. Analyzing WPOI is essential in reporting HP specimens in OSCC. High-risk WPOI can act as an independent predictor for LNM, early recurrence and poor prognosis. Incorporation of WPOI into TNM staging is recommended to improve clinician's ability to prognosticate and individualize treatment strategies.

[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).

Worst pattern of invasion and other histopathological features in oral cancer as determinants of prognosis and survival rate: A retrospective cohort analysis

Oral cavity squamous cell carcinoma (OCSCC) is a well-recognized malignancy of the head and neck. Studies on patients with early-stage oral cancer have shown that they develop locally recurring and/or regional lymph node metastasis, which results in disease-associated mortality. Thus, early-stage oral cancer does not always present good prognoses. The present study aimed to determine the efficacy of using worst pattern of invasion (WPOI) and other histopathological features, such as prognostic factors in OCSCC, and analyze the impact of resection margin status and histopathological prognostic indicators on local recurrence (LR) and overall survival (OS) in patients with OCSCC. A retrospective cohort study was conducted by reviewing the charts of 63 patients with OCSCC treated with primary surgery at King Abdulaziz University Hospital between 2012 and 2019. An author and an experienced pathologist reviewed pathology slides. Associations of histopathological factors, including differentiation, stage, lymphovascular invasion, extracapsular extension, perineural invasion (PNI), WPOI and surgical margins, with LR or disease-free survival (DFS) were evaluated. Univariate analysis identified WPOI and PNI, and multivariate analysis identified the WPOI as predictive factors for LR and DFS. Kaplan-Meier analysis identified the WPOI and PNI as predictive factors for OS and WPOI as a predictive factor for DFS. Therefore, it may be concluded that WPOI and PNI are significant independent prognostic factors for local tumor control and DFS in patients with OCSCC.

Early-Stage Oral Tongue Squamous Cell Carcinoma and a Positive Sentinel Lymph Node Biopsy: Description of a Prognostic Correlation between Pre-Treatment Inflammatory Biomarkers, the Depth of Invasion and the Worst Pattern of Invasion

The aim of this study was to investigate the correlation between pre-treatment inflammatory biomarkers and the post-operative depth of invasion (DOI) and worst pattern of invasion (WPOI) in early-stage oral tongue squamous cell carcinoma (OTSCC) by means of positive sentinel lymph node biopsy (SLNB). A retrospective analysis of patients affected by cN0 T1-T2 OTSCC who had undergone an SLNB at the National Cancer Institute of Naples was performed. The patients were studied using an evaluation of the pre-treatment neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammatory index (SII), and a histopathological analysis of the DOI and WPOI. The statistical analysis showed that among the prognostic biomarkers, the NLR was a significant predictor of high WPOI values (p = 0.002). The cut-off NLR value was 2.52 with a probability of developing a positive sentinel lymph node biopsy (SLNB) of 30.3%. In contrast, the DOI value was 5.20 with a probability of developing a positive SLNB of 31.82%. Regarding the WPOI, increasing the WPOI class increased the likelihood of a positive SLNB occurrence, and a positive significant correlation was found between the WPOI and SLNB (Csp = 0.342; p < 0.001). Pre-treatment NLR, together with post-surgical DOI and WPOI, can be a reliable predictor of occult neck metastasis in patients affected by early-stage OTSCC with a clinically negative neck. Further prospective studies with a larger series will be needed to confirm the results obtained and to better define the NLR, WPOI and DOI cut-off values in order for elective neck dissection to be recommended in relation to a clinically negative neck.

The Emerging Impact of Tumor Budding in Oral Squamous Cell Carcinoma: Main Issues and Clinical Relevance of a New Prognostic Marker

Tumor Budding (TB) represents a single cancer cell or a small cluster of less than five cancer cells on the infiltrative tumor front. Accumulating evidence suggests TB is an independent prognostic factor in oral squamous cell carcinoma (OSCC). However, its exact role is not yet elucidated, and a standardized scoring system is still necessary. The study aims to extensively review the literature data regarding the prognostic role of TB in OSCC. The results of TB are an independent prognostic factor of poor survival outcomes in OSCC. To date, the manual detection of hematoxylin and eosin-staining or pancytokeratin-immunostaining sections are the most commonly used methods. Between the several cut-offs, the two-tier system with five buds/field cut-offs provides better risk stratification. The prognostic role of the BD model in predicting survival outcomes was extensively validated; however, the inclusion of DOI, which is already a staging parameter, encouraged other authors to propose other models, integrating TB count with other adverse risk factors, such as the tumor–stroma ratio and tumor-infiltrated lymphocytes. The prognostic relevance of TB in OSCC highlights its evaluation in daily pathological practice. Therefore, the TB detection method and the TB scoring system should be validated based on tumor stage and site.

Emerging histopathologic markers in early-stage oral tongue cancer: A systematic review and meta-analysis

Although there are many histopathologic prognosticators, grading of early oral tongue squamous cell carcinoma (OTSCC) is still based on morphological cell differentiation which has low prognostic value. Here we summarize the emerging histopathological markers showing powerful prognostic value, but are not included in pathology reports. Using PubMed, Scopus, Ovid Medline, and Web of Science databases, a systematic literature search was preformed to identify early OTSCC studies that investigated the prognostic significance of hematoxylin–eosin‐based histopathologic markers. Our meta‐analysis showed that tumor budding was associated with overall survival (hazard ratio [HR] 2.32; 95% CI 1.40–3.84; p < 0.01) and disease‐specific survival (DSS) (1.89; 95% CI 1.13–3.15; p = 0.02). Worst pattern of invasion was associated with disease‐free survival (DFS) (1.95; 95% CI 1.04–3.64; p = 0.04). Tumor–stroma ratio was also associated with DFS (1.75, 95% CI 1.24–2.48; p < 0.01) and DSS (1.69; 95% CI 1.19–2.42; p < 0.01). Tumor budding, worst pattern of invasion, and tumor–stroma ratio have a promising prognostic value in early OTSCC. The evaluation and reporting of these markers is cost‐effective and can be incorporated in daily practice.

Prognostic significance of tumor budding thresholds in oral tongue squamous cell carcinoma

Oral tongue squamous cell carcinoma (OTSCC) represents the most common malignancy of the oral cavity. Tumor budding (TB) is a reliable prognostic factor in OTSCC; however, a standardized scoring system is not still validated. The study aims to evaluate the prognostic role of TB in 211 OTSCC patients treated between 1997-2018. TB was evaluated on haematoxylin and eosin-stained sections in the hotspot area of the infiltrative front (×200-magnification). It was scored using a two-tier, a three-tier system, and according to BD-model and revised-Grading system. Univariate and multivariate Cox regression analyses of disease-specific survival (DSS) and disease-free survival (DFS) were performed. A p-values<0.05 was considered as statistically significant. The two-tier and three-tier system resulted an independent prognostic factor of DSS. High-risk patients had a 2.21 and 3.08 times-increased probability of poor DSS compared to low-risk group. It is significantly increased even for intermediate-risk group. No significant differences emerged classifying patients according to BD-model and revised-Grading. These data confirm the prognostic value of TB in predicting DSS in OTSCC. Classifying patients in two groups using the 5-buds cut-off significantly discriminates their outcomes. Since the established role of DOI and the poor prognostic value of grading, TB could be considered an independent prognostic marker.

Mechanisms and Clinical Significance of Tumor Lymphatic Invasion

Tumor-associated lymphatic vessels play an important role in tumor progression, mediating lymphatic dissemination of malignant cells to tumor-draining lymph nodes and regulating tumor immunity. An early, necessary step in the lymphatic metastasis cascade is the invasion of lymphatic vessels by tumor cell clusters or single tumor cells. In this review, we discuss our current understanding of the underlying cellular and molecular mechanisms, which include tumor-specific as well as normal, developmental and immunological processes “hijacked” by tumor cells to gain access to the lymphatic system. Furthermore, we summarize the prognostic value of lymphatic invasion, discuss its relationship with local recurrence, lymph node and distant metastasis, and highlight potential therapeutic options and challenges.

Molecular and Clinical Implications of Somatostatin Receptor Profile and Somatostatin Analogues Treatment in Oral Cavity Squamous Cell Carcinoma

Simple Summary

The treatment of oral squamous cell carcinoma (OSCC) represents a significant problem worldwide. Among cancers with the highest incidence, OSCC renders one of the worst prognoses. Therefore, novel prognostic biomarkers and therapeutic tools to tackle OSCC are urgently needed. Somatostatin-analogues (SSA) are an invaluable therapeutic option in the treatment of several cancers. We aimed to determine the expression levels of all somatostatin-receptors (SSTs) in OSCC, compared to adjacent healthy control tissues, to analyze the relationship of SSTs expression with key clinical and histopathological data, and to explore the direct in vitro effect of different SSAs on OSCC cancer cells. Our findings highlight a potential role of SST₂ as a good prognostic biomarker for recurrence and metastasis in OSCC and unveil that SSA exerts antitumoral effects on OSCC cells, providing a relevant clinical conclusion, which should be soon tested for their use in humans.

Abstract

Oral squamous cell carcinoma (OSCC) incidence has increased by 50% over the last decade. Unfortunately, surgery and adjuvant radiotherapy and chemotherapy are still the mainstream modality of treatment, underscoring the need for alternative therapies. Somatostatin-analogues (SSA) are efficacious and safe treatments for a variety of tumors, but the presence of somatostatin-receptors (SSTs) and pharmacological effects of SSA on OSCC are poorly known. In this study, we demonstrated that SST₂ and SST₃ levels were significantly higher in OSCC, compared to adjacent healthy control tissues. SST₂ expression was associated with less regional metastasis and a lower recurrence rate. Moreover, SST₂ was elevated in OSCC and associated with histopathological good prognosis factors, such as high peritumoral inflammation, smaller depth of invasion, and expansive vs. infiltrative front of tumor invasion. Importantly, treatment with different SSA (octreotide, lanreotide, and pasireotide) significantly reduced cell-proliferation in OSCC primary cell cultures. Altogether, this study demonstrated that SST₂ is overexpressed in OSCC vs. healthy tissues and could represent a novel prognostic biomarker, since its expression is associated with tumors that show better prognostic factors and less recurrent rate. Moreover, our data unveil clear antitumoral effects of SSAs on OSCC, opening new avenues to explore their potential as targeting therapy to OSCC.

Oral cancer: changing the aim of the biopsy in the age of precision medicine. A review

Oral cancer is a heterogeneous disease that develops through a complex, multi-step process. Precision medicine should help to better understand its molecular basis, integrate traditional classifications and have a positive impact on cancer management. To apply this information in clinical practice, we need to define its histology and identify biomarkers expressed by the tumour that provide useful information for planning tailored treatment. The most reliable information currently derives from evaluation of biomarkers on post-operative samples. To plan personalised treatment, oncologists need to assess these markers on biopsy samples. We reviewed the recent literature and identified 6 of 184 publications that compared markers measured on biopsy and post-operative samples or assessed their predictivity for the development of lymph node metastases. Data from these studies suggest that markers measured on biopsy samples can provide useful indications for tailoring treatments. However, due to their heterogeneity and low level of evidence, these results need to be confirmed by clinical studies on a large population to standardise and validate biomarkers in biopsies and to assess their reliability in other diagnostic mini-invasive procedures such as radiomics and liquid biopsy.

Prognostic Role of Tumor-Infiltrating Lymphocytes and Tumor Budding in Early Oral Tongue Carcinoma

Objectives/Hypothesis

Occult lymph metastasis is an important prognosticator for the treatment of early oral tongue squamous cell carcinoma (SCC). The objective of this study was to evaluate the prognostic significance of tumor‐infiltrating lymphocytes (TILs) in early oral tongue SCC. The combination of the TIL subtype and intermediate‐ or high‐grade budding scores was investigated as a prognostic marker for occult neck metastases.

Study Design

Retrospective study.

Methods

Specimens from 62 patients with early oral tongue SCC treated with only primary surgery were analyzed by immunohistochemistry for CD4+, CD8+, FoxP3+, and CD45RO+ T cells and CD163+ macrophages. The highest number of each TIL subtype was counted in two areas of parenchyma and stroma in the tumor (Tumor) and peripheral stroma of the invasion margin.

Results

Based on multivariate analysis, a high density of Tumor CD163+ macrophages served as the poorest prognostic factor for regional control (RC) and disease‐free survival (DFS). Patients with both a high density of Tumor CD163+ macrophages and an intermediate‐ or a high‐grade budding score had a poor prognosis for RC according to the log‐rank test.

Conclusions

In summary, each TIL subtype may use different mechanisms during early and advanced stages of oral tongue SCC. A high density of Tumor CD163+ macrophages was determined to be a risk factor for RC and DFS as well as an additional stratification factor for RC in patients with intermediate‐ or high‐grade budding scores. Therefore, identifying TIL subtypes in daily clinical practice can help determine a more successful and individualized therapeutic approach for early oral tongue SCC.

Level of Evidence

Step 4 (Level 4) Laryngoscope, 131:2512–2518, 2021

The prognostic role of histologic grade, worst pattern of invasion, and tumor budding in early oral tongue squamous cell carcinoma: a comparative study

Major pathology guidelines often mandate stating the histologic grade as a component of the pathology report for various types of cancer. However, the prognostic value of histologic grade in head and neck squamous cell carcinoma (HNSCC) is controversial at best, and there is a need for more reliable prognostic histologic factors to better stratify and manage patients with HNSCC. In this study, we compared three relevant histopathologic features (histologic grade, worst pattern of invasion (WPOI), and tumor budding) in a large single-center retrospective cohort of early oral tongue squamous cell carcinoma (OTSCC) with tumor greatest dimension ≤ 4 cm. Only histologic grade predicted distant metastasis free survival (DMFS) on univariate analysis. Tumor budding was associated with nodal metastasis, overall survival (OS), regional recurrence-free survival (RRFS), and DMFS and was a significant predictor for nodal metastasis on the multivariable logistic regression model. WPOI 5 was associated with high frequency of nodal metastasis and shortened OS and was an independent adverse prognostic factor for OS on multivariate analysis using the Cox proportional hazards model. WPOI and tumor budding were prognostically more relevant than histologic grade. Consideration should be given to include WPOI and tumor budding in the pathology reporting of OTSCC.

The budding and depth of invasion model in oral cancer: A systematic review and meta-analysis

BACKGROUND

Tumour budding (B) and depth of invasion (D) have both been reported as promising prognostic markers in oral squamous cell carcinoma (OSCC). This meta-analysis assessed the prognostic value of the tumour budding and depth of invasion combination (BD model) in OSCC.

METHODS

Databases including Ovid MEDLINE, PubMed, Scopus and Web of Science were searched for articles that studied the BD model as a prognosticator in OSCC. PICO search strategy was "In OSCC patients, does BD model have a prognostic power?" We used the reporting recommendations for tumour marker prognostic studies (REMARK) criteria to evaluate the quality of studies eligible for systematic review and meta-analysis.

RESULTS

Nine studies were relevant as they analysed the BD model for prognostication of OSCC. These studies used either haematoxylin and eosin (HE) or pan-cytokeratin (PCK)-stained resected sections of OSCC. Our meta-analysis showed a significant association of BD model with OSCC disease-free survival (hazard ratio = 2.02; 95% confidence interval = 1.44-2.85).

CONCLUSIONS

The BD model is a simple and reliable prognostic indicator for OSCC. Evaluation of the BD model from HE- or PCK-stained sections could facilitate individualized treatment planning for OSCC patients.

Stromal categorization in early oral tongue cancer

Stromal categorization has been used to classify many epithelial cancer types. We assessed the desmoplastic reaction and compared its significance with other stromal characteristics in early (cT1-2N0) oral tongue squamous cell carcinoma (OTSCC). In this multi-institutional study, we included 308 cases treated for early OTSCC at five Finnish university hospitals or at the A.C. Camargo Cancer Center in São Paulo, Brazil. The desmoplastic reaction was classified as immature, intermediate, or mature based on the amount of hyalinized keloid-like collagen and myxoid stroma. We compared the prognostic value of the desmoplastic reaction with a stromal grading system based on tumor-stroma ratio and stromal tumor-infiltrating lymphocytes. We found that a high amount of stroma with a weak infiltration of lymphocytes was associated statistically significantly with a worse disease-free survival with a hazard ratio (HR) of 2.68 (95% CI 1.26–5.69), worse overall survival (HR 2.95, 95% CI 1.69–5.15), and poor disease-specific survival (HR 2.66, 95% CI 1.11–6.33). Tumors having a high amount of stroma with a weak infiltration of lymphocytes were also significantly associated with a high rate of local recurrence (HR 4.13, 95% CI 1.67–10.24), but no significant association was found with lymph node metastasis (HR 1.27, 95% CI 0.37–4.35). Categorization of the stroma based on desmoplastic reaction (immature, intermediate, mature) showed a low prognostic value for early OTSCC in all survival analyses (P > 0.05). In conclusion, categorization of the stroma based on the amount of stroma and its infiltrating lymphocytes shows clinical relevance in early OTSCC superior to categorization based on the maturity of stroma.

Elective Neck Dissection in T1N0M0 Oral Squamous Cell Carcinoma: When Is It Necessary?

PURPOSE

Elective neck dissection (END) versus observation remains controversial for cT1N0M0 oral cavity squamous cell carcinoma (OSCC). The aim of this study was to determine whether neck dissection is indicated for cT1N0M0 OSCC versus observation when considering oral cavity subsites and depth of invasion (DOI) as predictors.

PATIENTS AND METHODS

A multicenter, ambispective cohort study of patients with cT1N0M0 OSCC treated at the University of Michigan and Beijing Stomatological Hospital from August 1998 to July 2017 with a follow-up end date of July 2019 was performed. Patients were excluded if follow-up was less than 2 years and no neck disease had occurred or if the final pathologic analysis resulted in upstaging to T2 using American Joint Committee on Cancer criteria, eighth edition. A total of 283 patients met the criteria. The main outcome parameter was the 2-year neck metastatic rate.

RESULTS

The total 2-year lymph node metastatic rate was 11.3%. Overall neck metastatic rates escalated consistently according to DOI: less than 2 mm, 2.1%; 2 to 3 mm, 9.4%; 3 to 4 mm, 15.2%; and 4 to 5 mm, 24.6%. On univariate Cox regression analysis, DOI greater than 3 mm, tumor grade, and perineural invasion were statistically significant indicators of 2-year neck metastasis. On multivariate analysis, only DOI and tumor grade remained. On multivariate analysis of 2-year survival, no factors were independent predictors. Our proposed treatment strategy for END based both on statistically significant results for DOI and on review of the raw data using a 20% cutoff analysis showed cutoffs of 2 mm for the tongue (18.2%), 3 mm for the floor of the mouth (40.0%) and upper gingiva (20%), and 4 mm for the lower gingiva (33.3%) and no cutoff for the hard palate (0.0%).

CONCLUSIONS

The watch-and-wait approach remains a reasonable approach in selected patients with cT1N0M0 OSCC. Decision making for END in T1N0M0 patients should minimally consider tumor grade, DOI, and oral cavity subsite.