Genetic relationship between multiple squamous cell carcinomas arising in the oral cavity

Oral tumor heterogeneity, its implications for patient monitoring and designing anti-cancer strategies

Oral cancer tumors occur in the mouth and are mainly derived from oral mucosa linings. It is one of the most common and fatal malignant diseases worldwide. The intratumor heterogeneity (ITH) of oral cancerous tumor is vast, so it is challenging to study and interpret. Due to environmental selection pressures, ITH arises through diverse genetic, epigenetic, and metabolic alterations. The ITH also talks about peri-tumoral vascular/ lymphatic growth, perineural permeation, tumor necrosis, invasion, and clonal expansion/ the coexistence of multiple subclones in a single tumor. The heterogeneity offers tumors the adaptability to survive, induce growth/ metastasis, and, most importantly, escape antitumor therapy. Unfortunately, the ITH is prioritized less in determining disease pathology than the traditional TNM classifications or tumor grade. Understanding ITH is challenging, but with the advancement of technology, this ITH can be decoded. Tumor genomics, proteomics, metabolomics, and other modern analyses can provide vast information. This information in clinics can assist in understanding a tumor's severity and be used for diagnostic, prognostic, and therapeutic decision-making. Lastly, the oral tumor ITH can lead to individualized, targeted therapy strategies fighting against OC.

Elucidating the clonal relationship of esophageal second primary tumors in patients with laryngeal squamous cell carcinoma

Laryngeal cancer ranks as the second most prevalent upper airway malignancy, following Lung cancer. Although some progress has been made in managing laryngeal cancer, the 5-year survival rate is disappointing. The gradual increase in the incidence of second primary tumors (SPTs) plays a crucial role in determining survival outcomes during long-term follow-up, and the esophagus was the most common site with a worse prognosis. In clinical practice, the treatment of esophageal second primary tumors (ESPT) in patients with laryngeal squamous cell carcinoma (LSCC) has always been challenging. For patients with synchronous tumors, several treatment modalities, such as radiotherapy, chemotherapy and potentially curative surgery are necessary but are typically poorly tolerated. Secondary cancer therapy options for metachronous patients are always constrained by index cancer treatment indications. Therefore, understanding the clonal origin of the second primary tumor may be an important issue in the treatment of patients. LSCC cells demonstrate genetic instability because of two distinct aetiologies (human papillomavirus (HPV)-negative and HPV-positive) disease. Various etiologies exhibit distinct oncogenic mechanisms, which subsequently impact the tissue microenvironment. The condition of the tissue microenvironment plays a crucial role in determining the destiny and clonal makeup of mutant cells during the initial stages of tumorigenesis. This review focuses on the genetic advances of LSCC, the current research status of SPT, and the influence of key carcinogenesis of HPV-positive and HPV-negative LSCC on clonal evolution of ESPT cells. The objective is to gain a comprehensive understanding of the molecular basis underlying the clonal origins of SPT, thereby offering novel perspectives for future investigations in this field.

Clinical and prognostic features of multiple primary cancers with oral squamous cell carcinoma

OBJECTIVE

To characterize the epidemiological, clinical, and prognostic features of multiple primary cancers (MPC) following oral squamous cell carcinoma (OSCC).

DESIGN

Data from the Surveillance, Epidemiology, and End Results Program database were analyzed to determine the standardized incidence ratio (SIR) of multiple subsequent sites, difference in clinical and prognostic features between MPC and single primary OSCC.

RESULTS

The sites with the highest SIRs were the oral cavity (SIR = 69.48), other oral cavity and pharynx (SIR=55.46), pharynx (SIR=39.21), tonsils (SIR=33.52), trachea (SIR=33.24), esophagus (SIR=18.00), and larynx (SIR=13.12). The 5- and 10-year survival rates for single primary OSCC were 57.9% (95% CI: 56.7-59.2%) and 47.1% (95% CI: 45.7-48.6%), respectively, while those for MPC were 66.9% (95% CI: 64.6-69.4%) and 42.2% (95% CI: 39.5-45.2%), respectively. The mean age of MPC patients was significantly higher than that of single primary OSCC patients. MPC are more common in the gums and other sites of the oral cavity, and more likely to be detected in early TNM stage and pathological grade. Age, site, T-stage, and N-stage were significantly associated with prognosis of MPC.

CONCLUSIONS

Significant differences in clinical and prognostic features were found between MPC and single primary OSCC. Considering MPC has a poor long-term prognosis, it is necessary to identify MPC and single primary OSCC early.

Application of a non-invasive oral brushing procedure based on bisulfite sequencing of a 13-gene panel to study high-risk OSCC patients

BACKGROUND

A non-invasive sampling procedure for the early detection of Oral Squamous Cell Carcinoma (OSCC) based on DNA methylation analysis of a panel of 13 genes was applied in 4 different OSCC risk-group of patients. Aim of the study is to evaluate the between-group differences and the variables related to the methylation profile of each group.

METHODS

Oral brushing samples were collected from 54 healthy subjects, 31 Oral Leukoplakia (OL) patients, 18 Oral Lichen Planus (OLP) patients and 26 patients previously treated for OSCC. Each sample was considered positive or negative in relation to a predefined cut-off value.

RESULTS

None of the samples from 54 healthy subjects were positive, whereas 22/31 OL, 3/18 OLP and 8/26 surgically treated OSCC samples showed positive values with respect to the cut-off. In OL patients, dysplasia was the only variable significantly related to positive values: 10/10 OLs with high-grade dysplasia were positive with respect to 12/21 OLs without dysplasia (Chi 6.039, p< 0.05).

CONCLUSION

DNA methylation analysis in epithelial cells collected by oral brushing seems to be a promising genetic method to distinguish lesions at high risk of developing OSCC. Larger population studies and an adequate follow-up period are necessary to confirm these preliminary data.

Complications After Treatment of Head and Neck Venous Malformations With Sodium Tetradecyl Sulfate Foam

PURPOSE

The aim of this study was to evaluate complications in patients with head and neck venous malformations (VMs) treated with foam sclerotherapy using sodium tetradecyl sulfate (STS).

METHODS

The authors retrospectively evaluated the complications, pain. and degree of satisfaction in 69 consecutive patients affected by cervicofacial VM managed with STS using the Tessari method in a single institution.

RESULTS

The average number of procedures for each patient was 2.1. The most frequent complication was blistering. We observed 1 patient of temporary weakness of a facial nerve branch, 1 paradoxical embolism, and 1 orbital compartment syndrome.The average pain score was 0 (no pain at all) (51.5%). There was no statistically significant correlation between patient satisfaction and the presence of complications or the degree of pain.

CONCLUSIONS

Sclerotherapy with STS is an effective treatment that yields to very high patient satisfaction. This procedure has an overall low complication rate and is usually effective within a few sessions. However, severe complications may occur; these must be pointed out in the informed consent and the surgeon must be aware of and ready to quickly treat them to prevent long-term sequelae.

Identification of abnormal nuclear and mitochondrial genes in esophageal cancer cells

The present study aimed to detect the mutation characteristics of mitochondrial DNA (mtDNA) in Eca109 of Ec9706 cells, and to investigate their association with the nuclear genome (nDNA), thus providing a basis for gene targeting therapies for esophageal squamous cell carcinoma (ESCC). In vitro-cultured Ec9706 and Eca109 cells were analyzed the changes of single-nucleotide polymorphisms (SNPs), insertions/deletions (INDELs), copy number variation, and structure variation (SV) of their genome by high-throughput sequencing. The loci with SV on chromosome 1–12 of the two ESCC cell lines were ≥5% of the mtDNA, but SV on chromosome 13–22, X and Y was ≤3%; >40% of loci exhibited gain or loss; intergenic loci with INDEL changes and SNP features accounted for the majority of mutations. The affected genes encoded proteins including nDNA-encoding intra-mitochondrial-transporting proteins, ATP energy generation-associated proteins and mitochondrial electron respiratory chain proteins, and these proteins were all nucleus-encoded mitochondrial proteins. The transcription, duplication, and translation of the abnormally expressed mtDNA in Ec9706 and Eca109 cells were closely associated with disorders of nuclear DNA products.

Clonal analysis as a prognostic factor in multiple oral squamous cell carcinoma

OBJECTIVES

A novel classification based on molecular methods to assess clonality defines three types of secondary oral squamous cell carcinoma (OSCC): second primary tumour (SPT) independent from the index tumour, local recurrence (LR), clonally related to the primary tumour, and second field tumour (SFT), derived from the same genetically altered mucosal field as the primary tumour. The present study applied mtDNA analysis in a group of patients experiencing a second loco-regional neoplastic manifestation. The purpose was to differentiate secondary tumours into LRs, SPTs and SFTs and evaluate the prognostic impact in terms of survival rate.

MATERIAL AND METHODS

The study population comprised 23 patients who experienced a second neoplastic lesion after a surgical resection of primary OSCC. mtDNA D-loop analysis was applied in paired neoplastic lesions and in clinically and histologically normal mucosa. On the basis of mtDNA results, the second OSCC was classified as LR or SPT or SFT. Disease-free survival was defined as the duration between the appearance of the second neoplastic lesion and death of disease, or last follow-up visit.

RESULTS

Seven secondary tumours were classified as LR, 12 as SFT, 4 as SPT. An altered mucosal field proved a variable significantly related to a better survival rate (p<0.05); 2/12 (16.6%) SFT events failed as compared to 5/7 LRs (71.4%) and 3/4 SPTs (75%).

CONCLUSION

mtDNA analysis may be considered a useful tool to differentiate secondary tumours and might influence the choice of the most appropriate treatment in patients with multiple OSCCs.

Mitochondrial D310 mutation as clonal marker for solid tumors

Patients with multiple tumors, either synchronous or metachronous, can have metastatic disease or suffer from multiple independent primary tumors. While proper diagnosis of these patients is important for prognosis and treatment, this can be challenging using only clinical and histological criteria. The aim of the present study was to evaluate the value of mitochondrial D310 mutation analysis in diagnostic questions regarding tumor clonality for a wide range of tumor types. Sanger sequencing of D310 was performed on a diagnostic cohort of 382 patients with 857 tumors that were previously analyzed using routine molecular analysis on genomic DNA. The D310 mononucleotide repeat was frequently somatically mutated (56/321, 17 %) in several tumor types, including breast, head and neck, gynecological, lung, colorectal, and skin tumors. For 84/327 (26 %) patients, a D310 mutation was detected in at least one of their tumors; for these patients, D310 can be used to determine the clonal relationship between their multiple tumors. Clonality assessments based on mitochondrial DNA (mtDNA) and routine genomic DNA analysis were concordant in 52/73 (71 %) patients. We conclude that D310 mutation status might aid in determining clonality of clinically challenging synchronous or metachronous tumors. To this end, next generation sequencing targeted genomic DNA assays should be complemented with mtDNA markers, such as the D310 repeat.

Validation of Next-Generation Sequencing of Entire Mitochondrial Genomes and the Diversity of Mitochondrial DNA Mutations in Oral Squamous Cell Carcinoma

BACKGROUND

Oral squamous cell carcinoma (OSCC) is mainly caused by smoking and alcohol abuse and shows a five-year survival rate of ~50%. We aimed to explore the variation of somatic mitochondrial DNA (mtDNA) mutations in primary oral tumors, recurrences and metastases.

METHODS

We performed an in-depth validation of mtDNA next-generation sequencing (NGS) on an Illumina HiSeq 2500 platform for its application to cancer tissues, with the goal to detect low-level heteroplasmies and to avoid artifacts. Therefore we genotyped the mitochondrial genome (16.6 kb) from 85 tissue samples (tumors, recurrences, resection edges, metastases and blood) collected from 28 prospectively recruited OSCC patients applying both Sanger sequencing and high-coverage NGS (~35,000 reads per base).

RESULTS

We observed a strong correlation between Sanger sequencing and NGS in estimating the mixture ratio of heteroplasmies (r = 0.99; p<0.001). Non-synonymous heteroplasmic variants were enriched among cancerous tissues. The proportions of somatic and inherited variants in a given gene region were strongly correlated (r = 0.85; p<0.001). Half of the patients shared mutations between benign and cancerous tissue samples. Low level heteroplasmies (<10%) were more frequent in benign samples compared to tumor samples, where heteroplasmies >10% were predominant. Four out of six patients who developed a local tumor recurrence showed mutations in the recurrence that had also been observed in the primary tumor. Three out of five patients, who had tumor metastases in the lymph nodes of their necks, shared mtDNA mutations between primary tumors and lymph node metastases. The percentage of mutation heteroplasmy increased from the primary tumor to lymph node metastases.

CONCLUSIONS

We conclude that Sanger sequencing is valid for heteroplasmy quantification for heteroplasmies ≥10% and that NGS is capable of reliably detecting and quantifying heteroplasmies down to the 1%-level. The finding of shared mutations between primary tumors, recurrences and metastasis indicates a clonal origin of malignant cells in oral cancer.

Molecular events in relapsed oral squamous cell carcinoma: Recurrence vs. secondary primary tumor

Relapses have a great impact on both the morbidity and mortality rates of oral squamous cell carcinoma (OSCC) patients. Current classification criteria are imprecise and need improvements. Recent advances in understanding of OSCC relapses on a molecular level provide new possibilities to better classify true recurrences and second primary tumors. This review discusses the limitations of the current OSCC relapse classification method and presents possible alternatives to improve this classification based on molecular techniques. Moreover, these molecular techniques add to the further understanding of these lesions and may provide tools for clinical management.

Clonality analysis in primary oral squamous cell carcinoma and related lymph-node metastasis revealed by TP53 and mitochondrial DNA next generation sequencing analysis

The chance of developing a neck nodal metastasis after initial treatment of oral squamous cell carcinoma varies from 12.4% to 62%. Despite being the main reason for cancer-related mortality, nodal metastases are still rarely subjected to molecular analyses, and our knowledge of the clonal heterogeneity of multiple lesions within the same patient is limited. The aim of the present study was to evaluate the relationship between primary oral cancer and lymph node metastasis in a series of patients with synchronous and metachronous metastases by 2 clonality tests: mt-DNA and TP53 sequence analysis. The study population consisted of 10 consecutive patients. Data identified in this study demonstrate that our assay based on next-generation analysis of TP53 and mt-DNA is simple, is reliable, allows high throughput, and may be applied to retrospective cases. The combination of mt-DNA and TP53 data analysis helped us to evaluate more precisely and consistently the genetic relationship among different tumor clones.