RESUMEN
Oral cavity cancer is the most common type of head and neck cancer. There is no definitive standard diagnosis, prognosis, or treatment response biomarker panel based on simple, specific, non-invasive, and reliable methods for head and neck squamous cell carcinoma (HNSCC) patients. On the other hand, the frequent post-treatment biopsies make it challenging to discriminate residual disease or recurrent tumors following postoperative reparative and post-radiation changes. Saliva, blood plasma, and serum samples were commonly used to monitor HNSCC through liquid biopsies. Based on the evidence, the most prominent molecular-based fluid biomarker, such as circulating tumor DNA (ctDNA), has potential applications for early cancer diagnosis, screening, patient management, and surveillance. ctDNA showed genomic and epigenomic changes and the status of human papillomavirus (HPV) with the real-time monitoring of tumor status through cancer therapy. Due to the intra and inter-tumor heterogeneity of tumor cells like cancer stem cells (CSCs) and tumor microenvironment (TME) in HNSCC, the tiny tissue biopsy cannot reflect all genomic and transcriptomic abnormality. Most liquid biopsies are applied to detect circulating molecular biomarkers consisting of cell-free DNA (cfDNA), ctDNA, microRNA, mRNA, and exosome for monitoring tumor progression. Based on the results of previous studies, liquid biopsy can be applied for comprehensive multi-omic discovery by assessing the predictive value of ctDNA in both early and advanced cancers. Liquid biopsy can be used to evaluate molecular signature profiles in HNSCC patients, with great potential to help in early diagnosis, prognosis, surveillance, and treatment monitoring of tumors. These happen by designing longitudinal extensive cohort studies and the utility of organoid technology that promotes the context of personalized and precision cancer medicine.
RESUMEN
Cancer stem cells (CSCs) play a crucial role in tumor relapse, proliferation, invasion, and drug resistance in head and neck squamous cell carcinoma (HNSCC). This narrative review aims to synthesize data from articles published between 2019 and 2023 on biomarkers for detecting CSCs in HNSCC and changes in molecular pathways, genetics, epigenetics, and non-coding RNAs (ncRNAs) in CSCs relevant to precision medicine approaches in HNSCC management. The search encompassed 41 in vitro studies and 22 clinical studies. CSCs exhibit diverse molecular profiles and unique biomarker expression patterns, offering significant potential for HNSCC diagnosis, treatment, and prognosis, thereby enhancing patient survival. Their remarkable self-renewal ability and adaptability are closely linked to tumorigenicity development and maintenance. Assessing biomarkers before and after therapy can aid in identifying various cell types associated with cancer progression and relapse. Screening for CSCs, senescent tumor cells, and cells correlated with the senescence process post-treatment has proven highly beneficial. However, the clinical application of precision medicine in HNSCC management is hindered by the lack of specific and definitive CSC biomarkers. Furthermore, our limited understanding of CSC plasticity, governed by genomic, transcriptomic, and epigenomic alterations during tumorigenesis, as well as the bidirectional interaction of CSCs with the tumor microenvironment, underscores the need for further research. Well-designed studies involving large patient cohorts are, therefore, essential to establish a standardized protocol and address these unresolved queries.