Oral Lichen Planus and Mutated TP53-A Road to Cancer?

Genomic alterations in the stepwise progression from normal mucosa to metastasizing oral squamous cell carcinoma

Introduction

The aim of this study was to investigate the genomic changes that occur in the development from dysplasia, cancer and to regional metastases in patients with oral cavity squamous cell carcinoma (OSCC).

Material and methods

We included OSCC patients with lymph node metastases at diagnosis, treated with primary surgery at Rigshospitalet, University of Copenhagen in the period 2007-2014. The resected tumor specimens were evaluated by a pathologist, who marked areas of morphologically normal tissue and dysplasia surrounding the cancer, two areas from the cancer tissue, and one area within the lymph node metastases. From these areas a punch biopsy was taken, and DNA from each sample was extracted and sequenced using Illumina's TSO500 HT cancer panel.

Results

From 51 OSCC patients, 255 samples were included, comprising a wide variety of genomic alterations. Substantial intratumor heterogeneity was found. The most commonly mutated gene was TP53, mutated in 65% of all samples. Only two patients had no TP53 mutation in any samples. We found that morphologically normal appearing mucosa as well as surrounding dysplasia also contained malignant mutations, supporting the theory of field cancerization. There was a significant lower average tumor mutational burden (TMB) in the lymph node metastases compared to the primary tumors, supporting the theory of clonal selection.

Conclusion

Substantial inter- and intratumor genomic heterogeneity was found. Mutation of TP53 was the most common and was present in all but two patients. Our data strongly supports the theory of clonal selection and the theory of field cancerization.

Clinical and Biological Perspectives on Noncanonical Esophageal Squamous Cell Carcinoma in Rare Subtypes

Esophageal squamous cell carcinoma (ESCC) remains the most common malignancy of the esophagus worldwide. Environmental and lifestyle exposures such as alcohol and tobacco have been well defined in the pathogenesis of ESCC, acting in concert with cell intrinsic epigenomic, genomic and transcriptomic changes. However, a variety of nonenvironmental etiologies including Fanconi anemia, lichen planus, chronic mucocutaneous candidiasis, esophageal epidermoid metaplasia, epidermolysis bullosa, tylosis, esophageal atresia, and achalasia receive minimal attention despite a high risk of ESCC in these diseases. The goal of this review was to promote clinical recognition and suggest a diagnostic framework for earlier detection of ESCC in patients with these rare diseases. In all the discussed conditions, a change in symptoms should trigger a prompt endoscopic evaluation, and endoscopic surveillance programs with advanced imaging techniques and chromoendoscopy should be considered. Moreover, we leverage the convergence of these diseases on ESCC to identify common mechanisms underlying malignant transformation including aberrant proliferation, mucosal barrier dysfunction, increased inflammation, and genome instability. In this study, we summarize the clinical presentation, pathologic findings, potential screening strategies, and common mechanisms of malignant transformation associated with these rare diseases that drive ESCC.