Cell proliferation is associated with intensity of tumor budding in oral squamous cell carcinoma

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.

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.

The Tissue Architecture of Oral Squamous Cell Carcinoma Visualized by Staining Patterns of Wheat Germ Agglutinin and Structural Proteins Using Confocal Microscopy

OBJECTIVES

Tissue architecture and cell morphology suffer profound alterations during oral cancer and are important markers for its progression and outcome. For precise visualization of tissue architecture in oral cancer, we used confocal microscopy to examine the staining pattern of wheat germ agglutinin, a lectin that binds membrane glycoproteins, and the staining patterns of structural proteins.

MATERIALS AND METHODS

Paraffin sections of oral squamous cell carcinoma were stained with fluorescently labeled wheat germ agglutinin and with antibodies against structural proteins, which were revealed by immunohistochemistry with tyramide signal amplification.

RESULTS

Membrane localization of wheat germ agglutinin was markedly decreased in the basal layers and in regions of tumor invasion, accompanied by cytoplasmic redistribution of E-cadherin, β-actin and syndecan-1. Wheat germ agglutinin staining clearly identified tumor clusters within the surrounding stroma, and tumor cells with elongated morphology.

CONCLUSIONS

Our results suggest that the wheat germ agglutinin staining pattern is indicative of the degree of cell cohesion in oral squamous cell carcinoma, which decreases in basal layers and invasive tumor clusters with more migratory morphologies. Wheat germ agglutinin staining in combination with confocal microscopy could constitute, therefore, a valuable tool for the study of tissue architecture in oral cancer.

Tumour budding in solid cancers

Tumour budding is an emerging prognostic biomarker in colorectal cancer (CRC) and other solid cancers. Tumour buds are usually defined as isolated single cancer cells or clusters of up to four cancer cells located at the invasive tumour front. The prognostic value of tumour budding is now supported by a large body of evidence, whereas the utility of this phenotype as a predictive biomarker remains under investigation. The application of tumour budding indices in clinical practice requires a standardized scoring system that can be tailored to specific tumour types and clinical scenarios. In the context of CRC, tumour budding can be assessed according to the method agreed at the International Tumour Budding Consensus Conference (ITBCC) in 2016. Using the ITBCC scoring system, tumour budding is an independent predictor of lymph node metastasis in patients with pT1 CRC and of unfavourable survival in patients with stage II colon cancer. Regardless of the clinical scenario or tumour type, the assertion that 'the more tumour buds, the worse the clinical outcome' applies. In this Review, we provide an overview of tumour budding in solid cancers, highlighting the molecular and biological aspects of this phenomenon, including its associations with epithelial-mesenchymal transition and features of the tumour microenvironment. We also describe the available evidence demonstrating the value of tumour budding as a biomarker across various solid cancers.

Can morphological features evaluated in oral cancer biopsies influence in decision-making? A preliminary study

Tumor budding (TB) is a promising prognostic marker in many cancers including oral squamous cell carcinoma. The evaluation of TB in preoperative diagnostic biopsies has been proven be possible; therefore, the association of TB with other morphological features can represent an important aid in the previous treatment decision. This study aims to evaluate TB in oral squamous cell carcinoma (OSCC) biopsies, assessing its association with other morphological characteristics of the sample. A total of 56 cases of OSCC were investigated. In hematoxylin and eosin-stained slides, morphological features including histopathological grading and mode of invasion were evaluated in the deep invasive front. Moreover, immunohistochemistry was performed with anti-multi-cytokeratin antibody helping in the identification of TB, which was graded as low-intensity or no TB and high-intensity TB. Descriptive and bivariate analyses were performed, and the level of significance was set at 5%. The tongue was the most-affected site with 29 (51.7 %) tumors. The predominant mode of invasion (27-48.2 %) was by groups of neoplastic cells without clear boundaries. Of the cases investigated, 37 (66.1 %) were high-intensity TB, which was associated with the mode of invasion of the tumors (p < 0.05). All cases with the worst mode of invasion showed high-intensity TB. Preliminary results showed the potential of morphological features, such as TB and mode of invasion, evaluated in diagnostic specimens of OSCC, aiding in the treatment decision to select patients who could benefit from more-aggressive treatments.

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Tumor budding is a potential histopathological marker in the prognosis of oral squamous cell carcinoma: Current status and future prospects

Tumor budding (TB) is a histopathologically evident feature that represents a scattered pattern of invasion consisting of isolated single tumor epithelial cells or tumor cells in small clusters (up to 5 cells) seen primarily at the invasive front dispersed within the stroma for variable distance. Presence of TB has been linked with lymph node metastasis, recurrence, distant metastasis and reduced survival in numerous cancers including oral squamous cell carcinoma (OSCC). Tumor buds are also considered as histopathological markers of epithelial-mesenchymal transition which is a molecular process implicated as a hallmark for invasion and metastasis. This review gives an overview of the current evidence regarding TB assessment in OSCC and its future prospects.

Hallmarks of cancer: Tumor budding as a sign of invasion and metastasis in head and neck cancer

Invasion and metastasis are hallmarks of cancer. The concept of tumor budding at tumor-host interface has been documented in many carcinomas. A growing body of evidence indicates that tumor budding is a sign of invasion and early step for metastasis of many epithelial cancers including head and neck squamous cell carcinoma (HNSCC). In addition, recent research has underlined the importance of tumor budding as a promising prognosticator in HNSCC. This review summarizes the findings regarding tumor budding in HNSCC and focuses on the role of tumor budding in invasion and metastasis. Also, we highlight the prognostic significance of tumor budding in HNSCC and its potential for improving clinical decision making in terms of recommending optimal individualized treatment for this patient population.

High CD3+ lymphocytes, low CD66b+ neutrophils, and scarce tumor budding in the invasive front of lip squamous cell carcinomas

OBJECTIVE

This study aimed to evaluate tumor budding (TB) and quantify the neutrophilic and lymphocytic infiltration in the invasive front of lip squamous cell carcinomas. In addition, the associations between these features and the histopathological grading in the invasive front were analyzed.

DESIGN

A total of 43 lip squamous cell carcinoma surgical specimens were included and classified in accordance with a histological invasive front grading system. Immunohistochemistry was performed for CD66b and CD3 for the evaluation of neutrophils and T lymphocytes, respectively, in the invasive front of the tumors. Tumor budding was evidenced by AE1/AE3 staining.

RESULTS

Thirty-six (83.7%) of the tumors were well-differentiated tumors. Eleven (25.6%) of the cases exhibited high-intensity tumor budding. There were low neutrophil and high T lymphocyte infiltrations in the invasive front, leading to a low neutrophil/T lymphocyte ratio in the same region. Moreover, we found an association between tumor budding and the pattern of invasion, and between the CD3⁺ cell count and the inflammatory infiltrate (p < 0.05).

CONCLUSIONS

The low neutrophil and high T lymphocyte infiltration in the invasive front, and the few high-intensity tumor budding cases are in accordance with the histopathological features of well-differentiated lip tumors. If these characteristics remain in lip squamous cell carcinomas with more aggressive histopathological features, it deserves to be investigated.

Immunolocalization of Cancer Stem Cells Marker ALDH1 and its Association with Tumor Budding in Oral Squamous Cell Carcinoma

Tumor budding is a prognostic marker for oral squamous cell carcinoma (OSCC) characterized by the presence of isolated or small clusters of neoplastic cells at the tumor invasive front. Aldehyde dehydrogenase-1 (ALDH1) is associated with tumorigenesis, linked to treatment resistance and shown to identify cancer stem cells (CSC)-like cells. This study aimed to evaluate the expression of ALDH1 and its association with tumor budding in OSCC. Immunohistochemistry was employed in 163 OSCC samples to identify pancytokeratin (AE1/AE3) and ALDH1. While pancytokeratin (AE1/AE3) identified squamous tumor buds, the CSC-like cells were identified using ALDH1. A Chi square test was used to evaluate association between ALDH1 expression and tumor budding, while McNemar's test was used to identify differences in ALDH1 expression between the budding area and the area outside the budding. A positive expression of ALDH1 was observed in 47.24% of the samples and in 70% of anatomic locations affected. No association was observed between ALDH1 expression and tumor budding (p > 0.05). In tumors with high-intensity tumor budding, ALDH1 expression was higher in the budding area than in the area outside the budding (p < 0.05). The finding that tumor bud cells in OSCC show phenotypic characteristics of CSC-like cells reinforces the relevance of tumor budding in determining the biological behavior of this malignant neoplasm. Moreover, the presence of CSC-like cells in nearly half of evaluated samples of OSCC and in most of the affected anatomic locations is in accordance with the CSC model of oral carcinogenesis.