According to our selection criteria, a total of 143 papers reporting 78 distinct prognostic biomarkers were found (Fig. 1). 71 investigations were carried out on tissue specimens (Table 1) and (Table 2), while 11 studies examined biomarkers obtained from blood samples (Table 3). The majority of the studies were performed on tumours of the oral cavity. The first section of this study covers traditional prognostic variables, such as the prognostic and predictive value of imaging-based biomarkers; also gives a gestalt idea about the innovative prognostic factors, such as tissue biomarkers and circulating blood biomarkers. Higher expression or increased copy number for the majority of biomarkers (Table 1–3) were linked to a poor prognosis. Collectively, our results imply that the majority of the discovered biomarkers serve as prospective selection markers for molecular treatment approaches as well as unique tools for predicting patient outcomes.
Conventional Clinical Prognostic Variables
A physical examination, imaging tests (such as ultrasonography, CT, MRI, and PET), and histopathological categorisation are used to establish the diagnosis of HNSCC. This diagnostic work ultimately offers treatment recommendations based on conventional prognostic factors like tumour location and size, involvement of lymph nodes, metastatic distance, and tumour classification. Since tumours are entirely removed or inoperable surgery has a worse prognosis, surgery can still play a significant part in the multimodal treatment of HNSCC. It can also be a prognostic factor obtained from the surgical resection margin.
A full microscopic excision of the tumour with a sufficient margin of safety is the intended outcome of surgery; otherwise, adjuvant radiation treatment should be combined with adjuvant chemotherapy (Luryi et al. 2015). However, in individuals with HNSCC, adjuvant treatment may have an impact on functional outcomes. Before it was realised that HPV status had a significant predictive impact, three criteria were frequently used to stratify the risk of patients undergoing first surgery. According to TNM 7th edition (TNM-7), a high-risk postoperative situation is one in which the resection margin (R1) at the initial site is involved or extra-capsular spread to varying degrees of lymph node involvement. Both of these are independent prognostic factors for the overall survival of HNSCC (evidence level IIa) (TNM Classification 2009).
For HPV-induced oropharyngeal carcinoma, these classifications must be modified because high-risk patient populations are currently identified by the presence of five or more lymph node metastases, a T stage of three or four, and the presence of a tumour boundary, whereas extra-capsular spread and lymph node progression do not indicate local recurrence (Sinha et al. 2015). These modifications to the HNSCC-positive HPV risk categorisation reflect an important variance in treatment strategies. Only retrospective series data are available for intermediate- and low-risk postoperative circumstances (grade III evidence), and they permit chemotherapy dosage decrease to target volumes or, in some circumstances, termination. concomitant medical care. Retrospective studies of oral cavity cancer and oropharyngeal carcinoma have been conducted over the past ten years to assess the effectiveness of robotic transverse surgery (Achim et al. 2018).
The largest of these studies examined the records of 410 patients who had laryngeal and oropharyngeal cancer and had had transregional robotic surgery alone (47%) or adjuvant radiation therapy alone (31%), or both (21%) or none of these treatments. Two-year cancer results comparable to those for early T1 or T2 oropharyngeal carcinoma after radiation intensity-adjusted high-dose treatment in terms of regional control, disease-specific survival, and overall survival of more than 90%. 70% of patients with cervical dissection and 47.3% of all patients had robotic surgery. Weight loss, the Head and Neck Cancer Performance Scale (a validated instrument for measuring functional status), and the Performance Status Scale were used to determine the long-term functional and quality of life outcomes following robotic surgery. dietary rating (EAT-10), a popular and widely used ten-point verified dysphagia scale (Yeh et al. 2015; de Almeida et al. 2015). As a result, the type of surgery performed on HNSCC patients has a significant predictive impact on the disease's prognosis.
Hpv'S Involvement In Prognosis And Prognostication
The past ten years have seen the emergence of HPV-associated oropharyngeal cancer as a unique subtype of HNSCC with a separate prognosis for survival. In HPV-negative tumours, recursive partitioning analysis revealed that bundle years, nodule status, and HPV status were all superior predictors of overall survival versus T stage alone (Ang et al. 2010). The following studies have validated the excellent prognosis of HNSCC HPV-positive, preferably in the oropharynx, independent of treatment mode (O’ Sullivan et al. 2016).
According to Li et al. (2018) population-based retrospective analysis of 2018 HNSCC cases from the US National Cancer Database, 41,950 of 175,223 patients had poor HPV status. most accurate predictor of overall survival At seven facilities in the United States, Canada, and the Netherlands, and Denmark, the International Cooperative Network for Oropharyngeal Cancer Staging (ICON-S) screened 1907 patients with non-metastatic HPV-positive oropharyngeal cancer.
According to TNM-7 (2017), which was used to categorise patients with oropharyngeal cancer, the researchers discovered that stage I patients had the best overall 5-year survival (88% [95% CI 74–100]), stage II patients had the worst (82% [71–95]), stage III patients had the best (84% [79–89]), and stage VIA patients had the worst (81% [79–83]) (p = 0.25). 60% [53–68] of stage IVB; p < 0 0001. Stages N0 (80% [95% CI 73–87]), N1-N2a (87% [83–90]), and N2b (83% [80]) did not vary in terms of overall 5-year survival, while stage N3 (59% [51–69]; p 0.0001) did. The ICON-S staging system, based on 5-year survival, was presented as a novel staging method exclusively for HPV-positive oropharyngeal malignancies. the following outputs are produced: stage I (T1 - T2N0 - N1), stage II (T1 - T2N2 or T3N0 - N2), stage III (T4 or N3), and stage IV (M1) (O’ Sullivan et al. 2016).
Fewer than five lymph nodes, as opposed to five or more lymph nodes from a cohort of 702 trained patients and inferior cervical lymph node involvement in stages I and II, were not taken into consideration for independent survival prediction overall (O’ Sullivan et al. 2016). The new 8th edition of TNM (TNM-8) for head and neck cancer, which focuses on tumours positive for HPV, is based on the ICON-S programme. The clinical stage changed in 93.9% of patients, while the pathological stage moved to a lower stage in 91.7% of patients, per the TNM-8 recommendations (Cramer et al. 2018). Reclassifying oropharyngeal cancer might have a significant influence on multimodal therapies, necessitating more clinical trial investigation.
Human papillomavirus positive Intensity to lessen side effects is needed given the specific clinical and epidemiological treatment aspects of HNSCC as previously discussed by Maxwell et al (2016). Therefore, it is crucially important from a clinical standpoint to identify reliable indicators of HPV-induced illness with favourable prognoses, such as HPV E6 or E7 mRNA suggestive of active HPV infection transcription. p16 (CDKN2A) expression can be employed as a substitute marker for HPV-induced oropharyngeal cancer, according to immunohistochemistry.
However, the prediction of disease-free survival was better when HPV DNA positive and p16 overexpression were combined than when each factor was present alone. After the illness has progressed (Deng et al. 2014), p16 or HPV status continues to be a reliable and independent predictor. Additionally, E6 or E7 protein serology is a highly accurate diagnostic marker for the identification of HPV-induced oropharyngeal cancer and might be a helpful tool for subtype classification. patients who are in danger of relapsing (Deng et al. 2014).
Furthermore, quantitative analysis of HPV 16 DNA in salivary mouthwash suggests potential as a screening tool for those with oropharyngeal cancer who are HPV-positive. Patients with HPV-positive oropharyngeal cancer can have recurrences of the disease detected by initial therapy and analysis of residual HPV 16 DNA in post-treatment mouthwash. Combining saliva and plasma analysis may even improve the accuracy of HPV DNA detection. It is yet unknown, though, if this noninvasive monitoring technology can detect a local or regional recurrence and when it would be best to do surgery to save the condition (Chai et al. 2016).
Bersani et al. (2017), in their research, to explore a variety of parameters, procured data from 258 oropharyngeal cancer patients, of which a person who is having a T staging of less than 3, has an above-average CD8 tumour-infiltrating lymphocyte positivity, has viral mRNA expression of the E2 protein, which improved progression-free survival and reduced the risk of death by less than 3%.
According to the TNM-7 stage, there were differences in overall survival across groups (stage I-II versus stage III vs stage III, p = 0.036; stage III vs stage IV, p = 0.031). Although stage I and stage II disease had worse 5-year survival rates than stage III and stage IV illness, this suggests that the TNM-7 staging method has limitations in this patient population (Nauta et al. 2018). The annual overall survival rate for stage I is 81%, stage II is 77%, and stage III is 48%. When compared to patients with p16-positive oropharyngeal cancer, patients with HPV DNA-negative, p16-positive patients had poorer overall survival, according to subgroup analysis. - Patients that test positive are probably chosen for de-escalation testing (Nauta et al. 2018).
Prognostic Variables Based On Non-invasive Imaging Techniques
Additional non-genetic variables are added to augment clinically proven prognostic markers, the majority of which have not yet been prospectively verified. Non-genetic prognostic variables are frequently unable to outperform conventional prognostic factors and are not cost-effective, therefore their broad usage in clinical practice has not been established. TNM stage, which measures tumour size, is a key prognostic indicator.
Non-invasive preoperative diagnostic procedures will be crucial for head and neck surgeons; for instance, knowing how far a tumour has progressed can assist doctors to avoid doing common unilateral or bilateral neck dissections and the illnesses that go along with them. Technetium-99m, a promising new radiopharmaceutical that targets the CD206 receptor (MMR), has the potential to replace the dissection of necks and the diseases it causes with minimally invasive sentinel lymph node insertion. It predicts cervical lymph node involvement with an overall accuracy rate of 98.8%. As a result, a significant phase 3 trial with 564 patients showed non-inferiority to follow-up PET or CT-guided 3 months after chemotherapy compared to planned colectomy. 82% of these patients had tumours in the oropharyngeal region, 61% had N2b stage and 75% had positive p16 disease (Mehanna et al. 2016).
A reliable non-genetic prognostic factor for HNSCC may also be radiographed, which are particular characteristics of imaging techniques including CT, MRI, and PET. New prognostic insights can be made based on a wealth of morphological and structural information and functional elements of tumour metabolism. The metabolic volume of the main tumour was found to be an independent predictive factor for individuals requiring surgery while on first treatment in a retrospective analysis of 80 patients (Zhang et al. 2016).
Zhang et al. (2016), did mathematical modelling of 902 radiographic variables of 778 patients with oropharyngeal cancer, revealing that radiographic indicators gleaned from common CT scans predicted HPV and p16 status. Tumour response was effectively evaluated by the tumour site following a cumulative dosage of 10–20 Gy (Hentschel et al. 2011). Improved regional control and survival were connected with a sharp decline in standardised uptake values.
A 24-novel radiographic marker associated with prognosis was established using CT guidance in a retrospective analysis of data from 120 patients, 84% of whom had oral cavity carcinoma. This marker continues to be an independent signature predictor of overall survival and the absence of a tissue progression model for multivariate risk regression. Prognostic performance can be further enhanced by integrating radiological markers with p16 status. Compared to patients with low signature ratings, people with high signature scores benefit from chemotherapy (Ou et al. 2017).
Signature Prognostic Molecular Markers
Numerous clinical trials that sought to shed light on the optimisation of multimodal HNSCC treatment have only mildly improved patient outcomes by altering the type, dosage, or sequencing. This finding implies that a tailored approach to cancer radiation therapy may be preferable to a one-size-fits-all strategy. Therefore, emerging approaches seek to enhance the choice of therapies based on specific biomarkers. This strategy will help identify the patient subgroups that are most likely to benefit from these techniques and have current standard therapies have little to no anti-tumour impact or none at all. We can anticipate novel molecular strategies.
Circulating Blood Biomarkers
Liquid biopsy is a less invasive technique for finding molecular biomarkers in bodily fluids that might be used as a new tool in the treatment of people with HNSCC. Table 1 shows the expression profiling of blood-derived indicators. These publications predicted the haematological parameter accuracy and the functioning of circulating tumour cells (CTCs)(Fang et al. 2013; Grobe et al. 2014).
The reported link between chronic inflammation and cancer progression has stoked interest in haematological indicators such as neutrophils, lymphocytes, platelet counts, and inflammatory proteins. First noted in nasopharyngeal cancer (He et al. 2012), a substantial impact of the neutrophil/lymphocyte ratio on prognosis was later established for additional important adnexa, including the oral cavity (Tinhofer et al. 2014), hypopharynx (Nakahira et al. 2016), and oropharynx (Ozturk et al. 2016).
A 2018 meta-analysis that included 24 research and over 6000 HNSCC patients indicated that mortality risk ratios consistently rise in individuals with a high neutrophil-to-lymphocyte ratio (Mascarella et al. 2018). The systemic activation of extracellular DNA aggregates linked to cytotoxic and proteolytic enzymes is a postulated pathophysiological mechanism to explain the poor prognosis in these individuals generated by neutrophils. By sequestering CTCs at the extracellular trap deposits of leukocytes, this so-called extracellular neutrophil trap appears to lead to an increase in lung and liver metastases (Park et al. 2016). Trapping extracellular neutrophils can also aid in the transformation of latent cancer cells into expanding metastases, as demonstrated in a laboratory mouse model of protracted inflammation brought on by smoke exposure. Low lymphocyte/neutrophil counts lower the chance of cancer recurrence (Park et al. 2016).
Although a causative relationship between neutrophils, CTCs, and active metastasis development in HNSCC has not been shown, independent research undertaken in the past 30 years has offered evidence for a potential role for CTCs in disease progression, which was discussed (Tinhofer et al. 2018). The discovery of CTCs is associated with a higher risk of local or distant recurrence, progression-free survival, and overall survival, which is consistent with the possible prognostic significance of CTCs. It would go beyond the scope of this study to review this research. One of the studies covered by our search method employed the semi-automatic CellSearch CTC detection system to find CTCs (Grobe al. 2014). In the second study, which used PCR-based detection, EGFR copies were used as substitute markers for CTCs (Tinhofer et al. 2014).
Both investigations revealed a substantial correlation between the presence of CTCs and the development of the illness, which is consistent with earlier results. When discussing the prognostic significance of CTCs in HNSCC, care should be taken due to the various classifications of CTC-positive samples and the inclusion of diverse patient groupings. In addition to clusters of CTCs with better metastasis-forming potential, and an expanded phenotypic in place of single CTC enumeration, it may be essential to deploy improved CTC enrichment procedures that draw a large number of CTCs. To make them more useful for diagnosis, they might need to be simple (Kulasinghe et al. 2018).
For instance, a CTC test that evaluates PD-L1 (Kulasinghe et al. 2018) expression might be a useful supplemental diagnostic tool to forecast the effectiveness of immune checkpoint blockade therapies. The neutrophil-to-lymphocyte ratio biomarker's key benefit is that it is simple to detect during standard blood count analysis. Contrarily, the CellSearch platform has not yet been widely employed in the diagnosis of HNSCC because of the absence of prospective trials demonstrating its efficacy, despite being licensed for clinical use by regulatory authorities.
Due to the use of various criteria for identifying high leukocyte/lymphocyte clusters and positive CTC blood samples, as well as the inclusion of varied groups of patients treated in prior research, the predictive significance of neutrophil/lymphocyte and CTC ratios is questionable. Undoubtedly, further research will be required to come to a firm judgement about the therapeutic use of these interesting liquid biomarkers.
Prognostic Indicators In Tissue Specimen
Table 13–15 depicted the genomic DNA biomarker and mRNA biomarkers. Immune histochemical biomarkers that play a vital role in cell migration, tumour invasion, tumour migration, cellular proliferation, epithelial-mesenchymal transformation and cell cycle regulation are depicted in Table 216–67. Here, the predictive significance of copy number change (n = 4 studies), the promoter methylation status of distal gene loci (n = 2), somatic variations or germline at a single nucleotide (n = 4), 77–80, and mRNA [suppressed] (n = 6) of single genes (n = 83,85,86, or genome (n = 82,84) were assessed.
The potential biomarker PD-L1, which can assess their expression by immunohistochemistry, was one found by our comprehensive literature search. When expressed in tumour cells or the tumour microenvironment, this biomarker has garnered a lot of interest and has been linked to anti-PD1 medication responses in several tumour types (Kulasinghe et al. 2018). PD-L1 is often expressed on the surface of tumour cells and infiltrates immune cells in several malignancies, including HNSCC. Upregulated signalling pathways, such as stimulation of the PI3K/AKT (PKB) pathway, appear to encourage component production in tumour cells. On the other hand, the interface of the tumour cell nest, where invading immune cells produce inflammatory molecules like interferon-γ, is where tumour cells and immune cells can adaptively express PD-L1 (Skinner et al. 2017).
It appears that the kind of mechanism that boosts PD-L1 expression in tumour tissue may also have an impact on the prognostic significance of the protein. This idea is reinforced by the finding that whereas PD-L1 expression is higher in tumour cells, inflammation-related PD-L1 expression in immune cells is linked with a positive prognosis (Ono et al. 2017; Muller et al. 2017; Christensen et al. 2017) is connected with negative results. Other indicators with significant clinical promise include EGFR overexpression and CCND1-related amplification of cyclin D1 overexpression. More than 90% of HNSCC133 patients express EGFR, which is the cause of the constitutive activation of mitotic signalling pathways (Balermpas et al. 2017).
The regulatory functions of CDK4 and CDK6, which translate mitotic signals into cell cycle progression, are performed by CCND1 (BCL-1). Therefore, treating EGFR and CCND1-dependent pathways together in HNSCC might be quite successful. Even in patients who were resistant to cetuximab or platinum, the first clinical study with the CDK4 and CDK6 inhibitors Palbociclib in conjunction with cetuximab in recurrent or metastatic HNSCC demonstrated outstanding tumour response rates (35% overall response rate) (Michel et al. 2016). Patient selection based on biomarkers, a technique now being investigated in the Foundation Research and European Organization for Cancer Treatment HNCG 1559, can even boost the efficacy of this strategy (UPSTREAM [NCT03088059]) (Galot et al. 2018).
Mitigating The Bias Involving Biomarker Translation
Even though the chosen biomarker studies satisfied our criteria for selection, we repeatedly discovered serious flaws in the study's design and statistical power. The relationship of many HNSCC sub-sites with insufficient statistical power for subgroup analysis, therapeutic heterogeneity, and the potential for unrecognised variables impacting patient outcomes are only a few of the limitations in most studies reviewed. Additionally, the results from bigger tissue slices may not be comparable to those from certain immunohistochemistry investigations’ use of microscopy. These flaws played a role in both false-positive and false-negative outcomes.
To mitigate this hidden bias, promising candidate biomarkers which necessitate the study of two or more independent groups is an effective tactic. EGFR, is the target of a clinically developed molecular therapy (cetuximab), with many additional possibilities (PD-L1, CCND1, PI3K, AKT, and FGFR) serving as potential targets. This circumstance demonstrates the inadequate correlation between the volume of entries and the enormous rise in our understanding of the molecular characteristics of HNSCC tumours from major studies like the TCGA study. The disease's molecular profile is still not very high. To further understand the processes, functional investigations in suitable preclinical models would be required to ascertain the biological significance of genetic variations and aberrant gene expression in HNSCC. Disease development and therapy resistance are mediated at the molecular level.
Several clinical researchers are focusing on the individual rather than particular groups, although the identification of molecular subtypes and the creation of the best subtype-specific therapy regimens will undoubtedly constitute milestones in HNSCC. The phenotype-based precision cancer method was developed based on the idea that biological reactions to chemical or genetic perturbations in specific patient ex vivo models might act as predictive indicators of clinic therapy response. Chia et al. (2017) provided the first evidence supporting the viability of such a therapy in HNSCC. The main cultures used in this investigation for drug screening came from patients. Hence predicts treatment outcomes in xenograft models consistently developed from matched patients. Comprehensive omics approaches that query these ex vivo cultures are utilised in conjunction with drug susceptibility profiling to make real-time treatment decisions and forecast tumour development in n = 1 clinical trials. Future research involving bigger patient cohorts is required to assess the viability and potential of such a strategy for standard therapeutic care (Chia et al. 2017).
The patient's genetic makeup and environmental exposure may also have an impact on the biomarker's connection with the outcome. This understanding may help to explain why certain studies do not consistently reveal the substantial relationships with survival found in well-controlled biomarker investigations in sizeable patient groups discovered, despite the same molecular testing, equivalent patient selection, and adequate statistical power. For instance, higher expression of APOBEC3A cytidine deaminase mRNA was identified as a signal Independent predictive predictor for overall and disease-specific mortality in a 2017 omics-based analysis in a Taiwanese cohort of patients with oral cavity cancer. In a TCGA dataset of 312 patients, the authors of the researchers observed no statistically significant correlation between APOBEC3A expression and overall survival (Chen et al. 2017).