Survival of patients with HPV-positive oropharyngeal cancer after radiochemotherapy is significantly enhanced

p62/SQSTM1-induced caspase-8 aggresomes are essential for ionizing radiation-mediated apoptosis

The autophagy–lysosome pathway and apoptosis constitute vital determinants of cell fate and engage in a complex interplay in both physiological and pathological conditions. Central to this interplay is the archetypal autophagic cargo adaptor p62/SQSTM1/Sequestosome-1 which mediates both cell survival and endoplasmic reticulum stress-induced apoptosis via aggregation of ubiquitinated caspase-8. Here, we investigated the role of p62-mediated apoptosis in head and neck squamous cell carcinoma (HNSCC), which can be divided into two groups based on human papillomavirus (HPV) infection status. We show that increased autophagic flux and defective apoptosis are associated with radioresistance in HPV(-) HNSCC, whereas HPV(+) HNSCC fail to induce autophagic flux and readily undergo apoptotic cell death upon radiation treatments. The degree of radioresistance and tumor progression of HPV(-) HNSCC respectively correlated with autophagic activity and cytosolic levels of p62. Pharmacological activation of the p62-ZZ domain using small molecule ligands sensitized radioresistant HPV(-) HNSCC cells to ionizing radiation by facilitating p62 self-polymerization and sequestration of cargoes leading to apoptosis. The self-polymerizing activity of p62 was identified as the essential mechanism by which ubiquitinated caspase-8 is sequestered into aggresome-like structures, without which irradiation fails to induce apoptosis in HNSCC. Our results suggest that harnessing p62-dependent sequestration of ubiquitinated caspase-8 provides a novel therapeutic avenue in patients with radioresistant tumors.

Tumour infiltrating lymphocytes in oropharyngeal carcinoma: prognostic value and evaluation of a standardised method

Tumour infiltrating lymphocytes (TILs) have been described as a biomarker for the host immune response against the tumour with prognostic properties. The International Immuno-Oncology Biomarkers Working Group (IBWG) proposed a standardised method for quantifying TILs in solid tumours to improve consistent and reproducible scoring. In this study, the methodology was tested in a retrospective population of oropharyngeal squamous cell carcinoma (OPSCC). TIL quantification was performed on 92 OPSCC samples (2004-2013) by four independent observers as described by the IBWG. Interobserver variability was assessed and results were correlated with clinicopathological variables and survival. TIL evaluation turned out to be challenging in OPSCC due to heterogeneity of TILs distribution, presence of pre-existing lymphoid tissue, surface ulceration or erosion and insufficient amount of intertumoural stroma in biopsies. Nonetheless, interobserver variability proved to be good to excellent. High stromal TILs (TILstr) and intratumoural TILs (TILtum) were both correlated to favourable overall survival and multivariate analysis showed TILstr to be the sole independent prognostic factor in OPSCC. The IBWG-proposed TIL quantification method is feasible and reproducible in OPSCC and provides valuable prognostic information regarding clinicopathological characteristics and overall survival. The use of this standardised methodology may facilitate implementation of TILs scoring as a prognostic biomarker in OPSCC.

Immuno-Oncological Biomarkers for Squamous Cell Cancer of the Head and Neck: Current State of the Art and Future Perspectives

The era of immune checkpoint inhibitors has altered the therapeutic landscape in squamous cell cancer of the head and neck (SCCHN). Our knowledge about the tumor microenvironment has fueled the research in SCCHN, leading to several well-known and less-known prognostic and predictive biomarkers. The clinical staging, p16/HPV status, and PD-L1 expression are currently the main tools for assessing the patients' diagnosis and prognosis. However, several novel biomarkers have been thoroughly investigated, some reaching actual significant clinical contributions. The untangling of the immune infiltrate with the subtyping of tissue-associated tumor infiltrating lymphocytes, tumor-associated macrophages, and circulating blood-based biomarkers are an interesting avenue to be further explored and prospectively assessed. Although PD-L1 expression remains the most important response predictor for immune checkpoint inhibitors, several flaws impede proper assessment such as technical issues, different scoring protocol, and intra-, inter-, and temporal heterogeneity. In addition, the construction of an immune-related gene panel has been proposed as a prognostic and predictive stratification but lacks consensus. Recently, the role of microbioma have also been explored regarding its systemic and antitumor immunity. This review gives a comprehensive overview of the aforementioned topics in SCCHN. To this end, the integration of these clinically advantageous biomarkers via construction of an immunogram or nomogram could be an invaluable tool for SCCHN in future prospects.

Photodynamic Therapy as a Potent Radiosensitizer in Head and Neck Squamous Cell Carcinoma

Simple Summary

Despite the advances in multimodality treatment strategies, more than 30% of patients with advanced head and neck squamous cell carcinoma (HNSCC) experience recurrence of the disease that is usually derived from the residual tumor. The goal of our study is to understand the molecular basis underlying radiotherapy resistance in advanced HNSCC and to identify a mechanism-based radiosensitizer. We found that the autophagic cell survival pathway is upregulated in therapy-resistant HNSCC. Photodynamic therapy (PDT) directed at the endoplasmic reticulum (ER)/mitochondria induces programmed cell death such as paraptosis and apoptosis in an autophagic adaptor p62-dependent manner, promoting radiotoxicity.

Abstract

Despite recent advances in therapeutic modalities such as radiochemotherapy, the long-term prognosis for patients with advanced head and neck squamous cell carcinoma (HNSCC), especially nonviral HNSCC, remains very poor, while survival of patients with human papillomavirus (HPV)-associated HNSCC is greatly improved after radiotherapy. The goal of this study is to develop a mechanism-based treatment protocol for high-risk patients with HPV-negative HNSCC. To achieve our goal, we have investigated molecular mechanisms underlying differential radiation sensitivity between HPV-positive and -negative HNSCC cells. Here, we found that autophagy is associated with radioresistance in HPV-negative HNSCC, whereas apoptosis is associated with radiation sensitive HPV-positive HNSCC. Interestingly, we found that photodynamic therapy (PDT) directed at the endoplasmic reticulum (ER)/mitochondria initially induces paraptosis followed by apoptosis. This led to a substantial increase in radiation responsiveness in HPV-negative HNSCC, while the same PDT treatment had a minimal effect on HPV-positive cells. Here, we provide evidence that the autophagic adaptor p62 mediates signal relay for the induction of apoptosis, promoting ionizing radiation (XRT)-induced cell death in HPV-negative HNSCC. This work proposes that ER/mitochondria-targeted PDT can serve as a radiosensitizer in intrinsically radioresistant HNSCC that exhibits an increased autophagic flux.

HPV-associated differential regulation of tumor metabolism in oropharyngeal head and neck cancer

HPV-positive oropharyngeal cancer patients experience significantly lower locoregional recurrence and higher overall survival in comparison with HPV-negative patients, especially among those who received radiation therapy. The goal of the present study is to investigate the molecular mechanisms underlying the differential radiation sensitivity between HPV-negative and HPV-positive head and neck squamous cell carcinoma (HNSCC). Here, we show that HPV-negative HNSCC cells exhibit increased glucose metabolism as evidenced by increased production of lactate, while HPV-positive HNSCC cells effectively utilize mitochondrial respiration as evidenced by increased oxygen consumption. HPV-negative cells express HIF1α and its downstream mediators of glucose metabolism such as hexokinase II (HKII) and carbonic anhydrase IX (CAIX) at higher levels, while the expression level of cytochrome c oxidase (COX) was noticeably higher in HPV-positive HNSCC. In addition, the expression levels of pyruvate dehydrogenase kinases (PDKs), which inhibit pyruvate dehydrogenase activity, thereby preventing entry of pyruvate into the mitochondrial tricarboxylic acid (TCA) cycle, were much higher in HPV-negative HNSCC compared to those in HPV-positive cells. Importantly, a PDK inhibitor, dichloroacetate, effectively sensitized HPV-negative cells to irradiation. Lastly, we found positive interactions between tonsil location and HPV positivity for COX intensity and COX/HKII index ratio as determined by immunohistochemical analysis. Overall survival of patients with HNSCC at the tonsil was significantly improved with an increased COX expression. Taken together, the present study provides molecular insights into the mechanistic basis for the differential responses to radiotherapy between HPV-driven vs. spontaneous or chemically induced oropharyngeal cancer.

A 5‑year update of patients with HPV positive versus negative oropharyngeal cancer after radiochemotherapy in Austria

Background

After publishing promising results for the treatment of patients with human papilloma virus (HPV) positive oropharyngeal cancer with radiochemotherapy regarding 2‑year survival, we present an update of the disease-specific and disease-free survival after 5 years.

Patients and methods

A total of 29 patients of which 18 were HPV negative and 11 HPV positive with squamous cell carcinoma of the oropharynx received radiation therapy with or without chemotherapy (cisplatin) or immunotherapy (cetuximab) between 2007 and 2009. At time of the present analysis, six patients are still alive including four with HPV positive and two with HPV negative oropharyngeal carcinoma, while 15 out of 16 patients with HPV negative tumors died and 1 died of another cause with evidence of disease.

Results

Since the 2‑year disease-specific survival of patients with HPV positive cancer of the oropharynx was published with 100% versus 30.4% in HPV negative tumors, we now present the 5‑year disease-specific survival after treatment, which was 85.7% in HPV positive versus 11.1% in HPV negative patients.

Conclusion

We present the results of patients receiving radiochemo(immuno)therapy for oropharyngeal cancer regarding the HPV status, which is still promising.

Impact of Sonic Hedgehog Pathway Expression on Outcome in HPV Negative Head and Neck Carcinoma Patients after Surgery and Adjuvant Radiotherapy

INTRODUCTION

HPV positive patients suffering from head and neck cancer benefit from intensified radiotherapy when applied as a primary as well as an adjuvant treatment strategy. However, HPV negative patients treated with surgery and adjuvant radiotherapy lack validated prognostic biomarkers. It is therefore important to define prognostic biomarkers in this particular patient population. Especially, ´high-risk groups´ need to be defined in order to adapt treatment protocols. Since dysregulation of the sonic hedgehog pathway plays an important role in carcinogenesis, we aimed to assess whether members of the sonic hedgehog-signaling pathway may act as prognostic factors in patients with HPV negative head and neck squamous cell carcinoma.

MATERIALS AND METHODS

In this prospective study, pretreatment tumor biopsies of patients with head and neck squamous cell carcinoma were taken during panendoscopy (2005 to 2008). All patients were treated with surgery and postoperative radiotherapy. After assessment of HPV and p16 status, protein expression profiles of the Sonic hedgehog-signaling pathway were determined by immunohistochemistry and tissue microarray analyses in 36 HPV negative tumor biopsies. Expression profiles of Sonic hedgehog, Indian hedgehog, Patched, Smoothened, Gli-1, Gli-2 and Gli-3 were correlated with patients´ clinical data, local-control rate, disease-free as well as overall survival. Data from The Cancer Genome Atlas databank were used for external validation of our results.

RESULTS

Gli-1 (p = 0.04) and Gli-2 (p = 0.02) overexpression was significantly linked to improved overall survival of HPV negative patients. Gli-2 (p = 0.04) overexpression correlated significantly with prolonged disease-free survival. Cox-multivariate analysis showed that overexpression of Gli-2 correlated independently (HR 0.40, 95% CI 0.16-0.95, p = 0.03) with increased overall survival.

DISCUSSION

Gli-1 and Gli-2 overexpression represents a substantial prognostic factor for overall and disease-free survival in patients with locally advanced HPV negative head and neck cancer undergoing surgery and postoperative radiotherapy.

Survival, recurrence and toxicity of HNSCC in comparison of a radiotherapy combination with cisplatin versus cetuximab: a meta-analysis

BACKGROUND

Cisplatin-based treatment has been considered the standard treatment regimen of HNSCC. Cetuximab is an emerging target therapy that has potential therapeutic benefits over cisplatin. Nevertheless, curative effects of cisplatin-based chemoradiotherapy (CRT) versus cetuximab-based bioradiotherapy (BRT) are still controversial.

METHODS

Potentially eligible studies were retrieved using PubMed, Embase and Medline. Basic characteristics of patients and statistical data were collected. A meta-analysis model was established to compare CRT and BRT.

RESULTS

Thirty-one eligible studies and 4212 patients were found. The pooled HRs with 95 % confidence intervals (CIs) for OS and PFS were 0.32 [0.09, 0.55] and 0.51 [0.22, 0.80], respectively, and both were in favor of cisplatin. However, 3-year survival and recurrence analysis of the subgroups showed no differences between the two groups (p > 0.05). In subgroup analysis, oropharyngeal primary tumors exhibited improved results by cetuximab with a pooled HR of 1.56 [1.14, 2.13] for PFS. Additionally, the HPV+ status was a significant factor in positive outcomes with cetuximab with a pooled HR of 1.12 [0.46, 2.17] for OS.

CONCLUSION

Long-term use of BRT showed no significant difference compared with CRT, and both arms showed different aspects of toxicity. In subgroup analysis, taking the effects of treatment and adverse events into consideration, cetuximab plus radiation may show superior responses regarding OS and PFS in patients who have HPV+ or primary oropharyngeal HNSCC, respectively, but physicians should administer them with caution.

Classical risk factors, but not HPV status, predict survival after chemoradiotherapy in advanced head and neck cancer patients

Purpose

Despite the advent of concomitant chemoradiotherapy (CCRT), the prognosis of advanced head and neck squamous cell carcinoma (HNSCC) patients remains particularly poor. Classically, HNSCC, especially oropharyngeal carcinomas, associated with human papillomavirus (HPV) exhibits better treatment outcomes than HNSCCs in non-infected patients, eliciting a call for the de-escalation of current therapies. To improve the management of HNSCC patients, we aimed to determine the impact of active HPV infection on patient response, recurrence and survival after CCRT in a population of heavy tobacco and alcohol consumers.

Methods

Paraffin-embedded samples from 218 advanced HNSCC patients, mostly smokers and/or drinkers treated by CCRT, were tested for the presence of HPV DNA by surrogate type-specific E6/E7 qPCR and p16 immunohistochemistry. Associations between the response to CCRT and patient outcomes according to HPV status and clinical data were evaluated by Kaplan–Meier analysis and both univariate and multivariate Cox regression.

Results

Type-specific E6/E7 PCR demonstrated HPV positivity in 20 % of HNSCC. Regarding HPV status, we did not find any significant relation with response to therapy in terms of progression-free survival or overall survival. However, we observed a significantly worse prognosis for consumers of alcohol and tobacco compared to nondrinkers (p = 0.003) and non-smokers (p = 0.03). Survival analyses also revealed that the outcome is compromised in stage IV patients (p = 0.007) and, in particular, for oral cavity, hypopharynx and oropharynx carcinoma patients (p = 0.001).

Conclusion

The risk of death from HNSCC significantly increases when patients are exposed to tobacco and alcohol during their therapy, regardless of HPV status.

[Is (chemo)radiotherapy really the future standard in the treatment of oropharyngeal carcinoma?]

Treatment of patients with oropharyngeal squamous cell carcinoma (OPSCC) requires interdisciplinary collaboration. Besides oncologic control, organ and function preservation are important priorities. One treatment option is primary concomitant chemoradiotherapy (CRT), particularly for locally advanced head and neck cancer. Another option is sequential CRT, where induction chemotherapy may be followed either by radiation alone or by CRT. An important aspect of these modalities is the development of functional sequelae with regards to swallowing as a direct consequence of radiogenic fibrosis, as well as tissue ctoxicity associated with cisplatin-based chemotherapy. Conventional open surgical approaches are being increasingly replaced by transoral surgical modalities with less treatment-related morbidity. As a further, equally important goal of appropriately indicated surgery, adjuvant (C)RT may be omitted or the dose significantly reduced. The advantages of primary surgery over primary CRT may be less obvious in cases still requiring adjuvant treatment, although not necessarily completely eliminated. For patients with human papillomavirus (HPV)-driven OPSCC, it is important to note that primary surgery may provide comparable or even increased survival benefit. To date, there is no evidence for a clear advantage of primary CRT over primary surgery in this group. In these cases, a de-escalated treatment package may be the preferred option. Here, the application of radioimmunotherapy as well as a reduced radiation dose may minimize long-term treatment-related morbidities.

Pre-therapeutic fibrinogen levels are of prognostic significance in locally advanced head and neck cancer

OBJECTIVES

The objective of this retrospective study was to clarify the potential prognostic significance of pre-therapeutic fibrinogen levels in head and neck squamous cell carcinoma (HNSCC) patients treated with curative intent by primary radiotherapy (RT) or with postoperative radiotherapy (PORT).

PATIENTS AND METHODS

We retrospectively analyzed data from 347 patients with histologically confirmed locally advanced HNSCC. Analysis was conducted separately for the patient collective treated with PORT (N = 141; 85.1 % AJCC stage III/IV) and for patients treated with primary RT (N = 206; 97.1 % AJCC stage III/IV). Kaplan Meier analyses as well as univariate and multivariate survival analyses were performed to identify factors associated with overall survival (OS).

RESULTS

The most relevant observation was that plasma fibrinogen levels were significantly associated with a reduction of overall survival rates. In the low-fibrinogen (below 411 mg/dL) postoperatively irradiated group, OS rates at 2 and 3 years were 86 and 83 %, and in the high-fibrinogen group 66 and 51 %, respectively. In the RT group with low fibrinogen levels, OS rates after 2 and 3 years were 74 and 53 %, and in the high-fibrinogen group 40 and 22 %, respectively. In multivariate analysis, elevated fibrinogen concentrations were associated with inferior OS in both the postoperatively (HR = 2.5; p = 0.001) as well as in the primarily irradiated (HR = 1.7; p = 0.003) group.

CONCLUSIONS

We conclude from these results that elevated pre-therapeutic fibrinogen may serve as a biomarker associated with worsened prognosis in locally advanced head and neck cancer patients treated by either RT or surgery followed by adjuvant radiotherapy.

HPV-Positive Oropharyngeal Carcinoma

Objective

Human papillomavirus-positive (HPV+) head and neck squamous cell carcinoma is increasing in incidence and appears to exhibit improved response to treatment and better survival than that of HPV– head and neck squamous cell carcinoma. The purpose of this systematic review was to examine the current literature regarding treatment and prognosis of HPV+ oropharyngeal squamous cell carcinoma (OPSCC) and identify whether type of treatment (primarily surgery vs primarily radiation) significantly affects survival rates.

Data Sources

PubMed and Cochrane Library databases.

Review Methods

A computerized search of the PubMed and Cochrane Library databases was performed to identify English-language articles published between January 1, 2000, and October 21, 2014. Studies were included only if they were prospective or retrospective observational series of OPSCC patients that reported HPV status, treatment regimen, and survival outcomes. Outcomes were determined for HPV+ and HPV– OPSCC patients, with subanalyses according to the type of treatment received.

Results

Fifty-six articles were eligible for this review. In the HPV+ analysis, the unadjusted hazard rate ratio (HR) for surgery vs radiation treatment was 1.33 ( P = .114). Nine confounders were considered, and HRs were adjusted for each covariate. While HRs were almost all >1 for all covariates, none of the HRs was statistically significant at P < .05. The HR for HPV– OPSCC was higher for radiation than surgery.

Conclusions

HPV+ OPSCC has an improved prognosis and lower rates of adverse events when compared with HPV– OPSCC. HPV– OPSCC had significantly worse outcomes when treated with primary radiation as compared with primary surgery. There was no statistically significant difference in HRs for HPV+ OPSCC with primary radiation vs primary surgery treatment.

Improved survival in HPV/p16-positive oropharyngeal cancer patients treated with postoperative radiotherapy

INTRODUCTION

In the literature, HPV infection and/or p16 positivity have been consistently demonstrated to correlate with improved response rates in oropharyngeal squamous cell carcinoma (OPSCC) patients treated with primary radiotherapy (RT) alone and in combination with chemotherapy. However, the exact role of HPV/p16 positivity in patients treated with postoperative RT is still unclear.

METHODS

We analyzed tumor samples for HPV-DNA and p16 expression and correlated these variables with treatment outcome in a series of 63 consecutively treated oropharyngeal cancer patients (95% stage III/IV). HPV and p16 analysis were performed using validated test systems. Survival was estimated by the Kaplan-Meier method. Cox proportional hazard regression models were applied to compare the risk of death among patients stratified according to risk factors.

RESULTS

Expression of p16 or high-risk HPV-DNA was detected in 60.3% and 39.6% of the tumors, respectively. p16 expression [overall survival (OS) at 2 years: 91%] as well as HPV infection (OS at 2 years: 95%) was associated with improved OS. Mean survival in p16-positive patients was 112 months compared to 64.6 months in case of p16 negativity. All HPV-positive tumors stained positive for p16. In a multivariable analysis, p16 positivity was associated with improved OS and with disease-free survival.

CONCLUSION

p16 expression and HPV infection are strongly associated with the outcome of postoperatively irradiated OPSCC patients. HPV and p16 double-negative OPSCC patients should be regarded as a distinct "very high-risk patient group" that may benefit from intensified or novel treatment combinations.

Significance of p16 expression in head and neck cancer patients treated with radiotherapy and cetuximab

BACKGROUND

HPV-infection, p16 positivity, and EGFR expression have been correlated with favorable responses of head and neck cancer patients treated with radiotherapy (RT) with or without chemotherapy. However, a possible correlation of HPV/p16 and EGFR status on the effect of RT in combination with cetuximab has not been sufficiently investigated.

MATERIALS AND METHODS

We analyzed tumor samples for p16 and EGFR expression and correlated these variables with treatment outcome. Cox-proportional-hazard regression models were applied to compare the risk of death among patients stratified according to risk factors. Survival was estimated by the Kaplan-Meier method. Results were compared with an institutional historical control group treated without cetuximab and with published data.

RESULTS

Expression of p16 was predominantly found in oropharyngeal squamous cell cancer patients (OPSCC; 36.6% positivity; 92% of all cases), while EGFR was expressed at high levels in all tumor subsites (82%). p16 expression was associated with improved overall survival in irradiated OPSCC patients (2-year overall survival of 80% in p16-positive vs. 33% overall survival in p16-negative patients). In a multivariable analysis covering all tumor sites, nodal stage (> N2a vs. ≤ N2a) and tumor site (OPSSC vs. non-OPSCC) had an impact on overall survival.

CONCLUSION

Our results show that p16 positivity is associated with a favorable outcome in OPSCC patients treated with RT and cetuximab.

Improved clearance during treatment of HPV-positive head and neck cancer through mTOR inhibition

Human papillomavirus (HPV)-related head and neck squamous cell carcinoma (HNSCC) incidence is increasing at a near epidemic rate. We investigated whether the mammalian (or mechanistic) target of rapamycin (mTOR) inhibitor, rapamycin, can be used as a concurrent agent to standard-of-care cisplatin/radiation therapy (CRT) to attenuate tumor lactate production, thus enhancing CRT-induced immune-mediated clearance of this antigenic tumor type. A C57Bl/6-derived mouse oropharyngeal epithelial cell line retrovirally transduced with HPV type 16 E6/E7 and human squamous cell carcinoma cell lines were evaluated for their response to rapamycin in vitro with proliferation assays, Western blots, and lactate assays. Clonogenic assays and a preclinical mouse model were used to assess rapamycin as a concurrent agent to CRT. The potential of rapamycin to enhance immune response through lactate attenuation was assessed using quantitative tumor lactate bioluminescence and assessment of cell-mediated immunity using E6/E7-vaccinated mouse splenocytes. Rapamycin alone inhibited mTOR signaling of all cancer cell lines tested in vitro and in vivo. Furthermore, rapamycin administered alone significantly prolonged survival in vivo but did not result in any long-term cures. Given concurrently, CRT/rapamycin significantly enhanced direct cell killing in clonogenic assays and prolonged survival in immunocompromised mice. However, in immunocompetent mice, concurrent CRT/rapamycin increased long-term cures by 21%. Preliminary findings suggest that improved survival involves increased cell killing and enhanced immune-mediated clearance in part due to decreased lactate production. The results may provide rationale for the clinical evaluation of mTOR inhibitors concurrent with standard-of-care CRT for treatment of HPV-positive HNSCC.

HPV positive tonsillar cancer in two laser surgeons: case reports

A 53 year-old male gynecologist presented with human papillomavirus (HPV) 16 positive tonsillar squamous cell carcinoma. He had no identifiable risk factors with the exception of long term occupational exposure to laser plumes, having performed laser ablations and loop electrosurgical excision procedures (LEEP) on greater than 3000 dysplastic cervical and vulvar lesions over 20 years of practice. The second patient is a 62 year old male gynecologist with a 30 year history of laser ablation and LEEP who subsequently developed HPV 16 positive base of tongue cancer. He also had very few other risk factors for oropharyngeal cancer or HPV infection. HPV is a probable causative agent for oropharyngeal squamous cell carcinoma and has been reported as being transmittable through laser plume. This paper suggests that HPV transmitted through laser plume can result in subsequent squamous cell carcinoma.

An analysis of the epidemiological and etiological factors of oral tumors of young adults in a Central-Eastern European population

The etiology of tumors in young age is not precisely known yet, but studies on the topic generally agree that in this group of patients the traditionally known behavioural risk factors (tobacco and alcohol abuse) play no or a significantly less important role. Oral squamous cell carcinoma occurring at a young age is a topic of utmost importance that is extensively and intensively researched as, while the overall incidence of oral cancer is decreasing worldwide, that of squamous cell carcinoma diagnosed in young adults is steadily increasing. The present article aims at presenting the main questions and characteristics of tumors in young adults in Central-Eastern Europe and in developed West European countries as contrasted to tumors found in middle aged and elderly patients. Factors influencing the development of oral cancer include regulatory factors of the cell cycle, the inherited vulnerability of the genetic code of certain proteins and the presence of HPV infection with an oncogenic genotype. The connections of HPV infection and genetic damages are studied intensively. It is known that the prevalence of oral HPV infections is growing with a background of potentially changing sexual habits. It is debated, however, whether smoking and alcohol consumption could have a connection to HPV associated oral cancer and whether the spread of HPV in itself could be an explanation for the growing occurrence of young-age tumors. There is no consensus in the literature as to the prognostic significance of age. Some research groups have found a better life expectancy for young patients, while other authors found a worse prognosis for these patients. It is known that the prognosis of head and neck tumors, the prevalence of HPV infections as well as genetic mutations show regional and ethnic variations. This might be explained by differences in the degree of development of a preventive system, in the quality of care and in the attitudes of young patients towards visiting a doctor. The study is made difficult by incomparable patient selection criteria as well as by the question of the intraoral localisation of tumors as an independent risk factor.