The prognostic role of sex, race, and human papillomavirus in oropharyngeal and nonoropharyngeal head and neck squamous cell cancer

Regulation of proliferation and cell cycle by protein regulator of cytokinesis 1 in oral squamous cell carcinoma

Protein regulator of cytokinesis 1 (PRC1), a microtubule-associated protein, has emerged as a critical regulator of proliferation and apoptosis, acting predominantly in numerous tumors. However, its function in oral squamous cell carcinoma (OSCC) is still unknown. To establish the roles of PRC1 in OSCC, 95 oral clinical samples (54 OSCC, 24 oral leukoplakia [OLK], and 17 normal oral mucosa) and seven oral cell lines (6 OSCC and 1 normal oral cell lines) were analyzed using a series of molecular and genomic assays both in vivo and in vitro were conducted in this study. Herein, we provide evidence demonstrating that expression of PRC1 closely correlates with the degree of epithelial dysplasia in OLK (n = 24) (p < 0.001), and the poor differentiation, large tumor volume, lymph node metastasis, and high-clinical stage in OSCC (n = 54) (p < 0.05), illustrating that PRC1 has a promotive influence on tumor progression in OSCC. Simultaneously, we observed that PRC1 knockdown in OSCC cell lines caused G2/M phase arrest (p < 0.05), inhibited cell proliferation in vitro (p < 0.05) and tumor growth in vivo (p < 0.001). Furthermore, the effects of PRC1 on the regulation of proliferation and cell cycle transition in OSCC samples were mediated by p53. The p53/PRC1/EGFR signaling pathway was found to be implicated in the tumor progression of OSCC. Based on our data, we demonstrate that PRC1 is a key factor in regulating proliferation and the cell cycle, pointing to the potential benefits of PRC1-targeted therapies for OSCC.

Increasing prevalence of human papillomavirus-positive oropharyngeal cancers among older adults

BACKGROUND

The incidence of oropharyngeal squamous cell carcinoma (OPSCC) is increasing among older adults. It is unknown whether these trends can be explained by human papillomavirus (HPV) and whether HPV-related tumors remain associated with an improved prognosis among older patients.

METHODS

In a retrospective study of OPSCCs diagnosed from 1995 to 2013 at 2 National Comprehensive Cancer Network-designated cancer centers, p16 immunohistochemistry and in situ hybridization (ISH) for HPV-16, high-risk DNA, and/or E6/E7 RNA were performed. The median age at diagnosis was compared by p16 and ISH tumor status. Trends in age were analyzed with nonparametric trends. Survival was analyzed with the Kaplan-Meier method and Cox proportional hazards models.

RESULTS

Among 239 patients, 144 (60%) were p16-positive. During 1998-2013, the median age increased among p16-positive patients (P_trend = .01) but not among p16-negative patients (P_trend = .71). The median age of p16-positive patients increased from 53 years (interquartile range [IQR] in 1995-2000, 45-65 years) to 58 years (IQR for 2001-2013, 53-64 years). Among patients ≥ 65 years old, the proportion of OPSCCs that were p16-positive increased from 41% during 1995-2000 to 75% during 2007-2013 (P_trend = .04). Among all age groups, including older patients, a p16-positive tumor status conferred improved overall survival in comparison with a p16-negative status.

CONCLUSIONS

The median age at diagnosis for HPV-related OPSCC is increasing as the proportion of OPSCCs caused by HPV rises among older adults. The favorable survival conferred by an HPV-positive tumor status persists in older adults. Cancer 2018;124:2993-9. © 2018 American Cancer Society.

The role of human papillomavirus on the prognosis and treatment of oropharyngeal carcinoma

Human papillomavirus positive oropharyngeal cancer (HPV-positive OPC) is a distinct subtype of head and neck carcinoma (HNC) distinguished from HPV-negative HNC by its risk factor profile, clinical behavior, and molecular biology. Compared to HPV-negative HNC, HPV-positive OPC exhibits significantly better prognosis and an enhanced response to treatment. Recognition of the survival benefit of HPV-positive tumors has led to therapeutic de-intensification strategies aiming to mitigate treatment-related toxicities while maintaining high response rates. In this review, we summarize key aspects of oral HPV infection and the molecular mechanisms of HPV-related carcinogenesis. We review the clinical and molecular characteristics of HPV-positive OPC that contribute to its improved prognosis compared to HPV-negative HNC. We also discuss current and emerging treatment strategies, emphasizing potential mechanisms of treatment sensitivity and the role of therapeutic de-intensification in HPV-positive OPC. Lastly, we examine literature on the management and prognosis of recurrent/metastatic HPV-positive OPC with a focus on the role of salvage surgery in its management.

Nomograms forecasting long-term overall and cancer-specific survival of patients with oral squamous cell carcinoma

Our aim was to establish a "nomogram" model to forecast the overall survival (OS) and cancer-specific survival (CSS) of oral squamous cell carcinoma (OSCC) patients. The clinicopathological data for the 10,533 OSCC patients were collected from the Surveillance, Epidemiology and End Results (SEER) database. We used a credible random split-sample method to divide 10,533 patients into two cohorts: 7046 patients in the modeling cohort and 3487 patients in the external validation cohort (split-ratio = 2:1). The median follow-up period was 32 months (1-119 months). We developed nomograms to predict 5- and 8-year OS and CSS of OSCC patients with a Cox proportional hazards model. The precision of the nomograms was assessed by the concordance index (C-index) and calibration curves through internal and external validation. The C-indexes of internal validation regarding 5- and 8-year OS and CSS were 0.762 and 0.783, respectively. In addition, the external validation's C-indexes were 0.772 and 0.800. Based on a large-sample analysis targeting the SEER database, we established two nomograms to predict long-term OS and CSS for OSCC patients successfully, which can assist surgeons in developing a more effective therapeutic regimen and conducting personalized prognostic evaluations.

Prognostic factors for human papillomavirus-positive and negative oropharyngeal carcinomas

OBJECTIVES/HYPOTHESIS

Human papillomavirus (HPV)-positive and HPV-negative oropharyngeal squamous cell carcinoma (OPSCC) are distinct disease entities. Prognostic factors specific to each entity have not been adequately explored. Goals for this study were: 1) to determine whether HPV-positive and HPV-negative OPSCCs have distinct prognostic factors, and 2) to explore the prognostic significance of sex and race in OPSCC after HPV stratification STUDY DESIGN: Retrospective case series.

METHODS

A retrospective review of 239 incident OPSCC patients from 1995 to 2012, treated at Johns Hopkins and University of California-San Francisco was conducted. Women and nonwhite races were oversampled. All analyses were stratified by tumor HPV in situ hybridization status. The effects of sex and race on survival were considered in Kaplan-Meier and unadjusted and adjusted Cox regression models.

RESULTS

One hundred thirty-four (56.1%) OPSCC patients were HPV positive. On univariate analysis, women had better overall survival than men among HPV-positive (hazard ratio [HR]: 0.47, 95% confidence interval [CI]: 0.20-1.07; P = .06) but not HPV-negative (HR: 0.73, 95% CI: 0.43-1.24; P = .24) OPSCCs. On multivariate analysis, women with HPV-positive OPSCCs remained at lower risk of death (adjusted hazard ratio [aHR]: 0.34, 95% CI: 0.12-0.96; P = .04). Survival did not vary significantly by race among HPV-positive patients. Among HPV-negative patients, Hispanic patients had significantly better survival in unadjusted (HR: 0.27, 95% CI: 0.08-0.91; P = .04) but not adjusted (aHR: 0.93, 95% CI: 0.11-7.36; P = .94) analysis.

CONCLUSIONS

Women with HPV-positive OPSCC may have improved overall survival compared to men. Sex does not play a prognostic role in HPV-negative OPSCC. There are no differences in prognosis by race among HPV-positive or HPV-negative patients.

LEVEL OF EVIDENCE

4 Laryngoscope, E287-E295, 2018.

Head and neck squamous cell cancers in the United States are rare and the risk now is higher among white individuals compared with black individuals

BACKGROUND

The increasing incidence of oropharyngeal squamous cell cancer (OPSCC) is well established. However, up-to-date incidence estimates and trends for head and neck squamous cell cancers (HNSCCs) overall, including major anatomic sites, and nonoropharyngeal (non-OP) HNSCCs by sex, race, and age in the United States are not well described.

METHODS

A retrospective analysis of incident HNSCCs during 1992 through 2014 using the Surveillance, Epidemiology, and End Results database was performed to evaluate the incidence of HNSCCs overall, OPSCC, and non-OP HNSCC (those of the larynx, oral cavity, hypopharynx, nasopharynx, and nasal cavity). Incidence rates were calculated overall and by subgroups of interest, and incidence rate ratios were used to compare rates between groups. The incidence rates presented were per 100,000 population and were age adjusted to the 2000 US standard population (19 age groups; Census P25-1130). The annual percent change (APC) was modeled with and without joinpoints.

RESULTS

The incidence of HNSCC overall declined (average APC [aAPC], -0.8; P<.001) despite significant increases in the incidence of OPSCCs, most notably between 2000 and 2014 (APC, 2.1; P<.001). Significant declines in incidence were observed for all non-OP HNSCC sites for both women and men (P<.001 each). Among women, the risk of OPSCC also significantly decreased (aAPC, -0.8; P = .002), whereas the risk among men was stable during 1992 through 2001 (APC, 0.4; P = .42) and then significantly increased from 2001 to 2014 (APC, 2.7; P<.001). Decreases in the risk of non-OP HNSCC were especially large for black women (aAPC, -2.6; P<.001) and men (aAPC, -3.0; P<.001). Although the incidence of HNSCC previously was highest among black individuals, since 2009 its incidence has been higher among white compared with black individuals.

CONCLUSIONS

The incidence of HNSCC is declining, especially for non-OP HNSCC and among black individuals. Cancer 2018;124:2125-33. © 2018 American Cancer Society.

Oral epithelial dysplasia, atypical verrucous lesions and oral potentially malignant disorders: focus on histopathology

The term oral potentially malignant disorders (OPMDs) describes a recognizable group of mucosal diseases that have a risk of progressing to squamous cell carcinoma. Oral leukoplakia, the most common OPMD, has a 1% prevalence and reported malignant transformation rates of 2% to 5%. Other OPMDs include erythroplakia, erythroleukoplakia, submucous fibrosis, lesions of reverse smokers, and inherited genetic disorders, such as Fanconi anemia. The histopathologic assessment of OPMDs is an area of subjectivity, and oral epithelial dysplasia (OED) is fraught with both interrater variability and intrarater variability. Both architectural and cytologic changes are utilized when developing criteria for grading OED. However, the concept of atypical verrucous lesions, particularly as it pertains to proliferative verrucous leukoplakia, suffers from lack of histopathologic diagnostic criteria. Histopathologic mimics of OPMDs, including reactive/regenerative epithelium, frictional keratosis, and infection, can result in patient mismanagement. This review will focus specifically on the histologic features of OED, including human papillomavirus-associated dysplasia, as well as the histologic features of atypical verrucous keratoses/hyperplasia, particularly those that arise in the setting of proliferative verrucous leukoplakia along with OPMD mimics.

Sensitivity and specificity of oral HPV detection for HPV-positive head and neck cancer

BACKGROUND

The incidence of HPV-related head and neck squamous cell carcinoma (HPV-HNSCC) is increasing. Oral samples are easy and non-invasive to collect, but the diagnostic accuracy of oral HPV detection methods for classifying HPV-positive HNSCC tumors has not been well explored.

METHODS

In a systematic review, we identified eight studies of HNSCC patients meeting our eligibility criteria of having: (1) HPV detection in oral rinse or oral swab samples, (2) tumor HPV or p16 testing, (3) a publication date within the last 10 years (January 2007-May 2017, as laboratory methods change), and (4) at least 15 HNSCC cases. Data were abstracted from each study and a meta-analysis performed to calculate sensitivity and specificity.

RESULTS

Eight articles meeting inclusion criteria were identified. Among people diagnosed with HNSCC, oral HPV detection has good specificity (92%, 95% CI = 82-97%) and moderate sensitivity (72%, 95% CI = 45-89%) for HPV-positive HNSCC tumor. Results were similar when restricted to studies with only oropharyngeal cancer cases, with oral rinse samples, or testing for HPV16 DNA (instead of any oncogenic HPV) in the oral samples.

DISCUSSION

Among those who already have HNSCC, oral HPV detection has few false-positives but may miss one-half to one-quarter of HPV-related cases (false-negatives). Given these findings in cancer patients, the utility of oral rinses and swabs as screening tests for HPV-HNSCC among healthy populations is probably limited.

Mouse model of postsurgical primary tumor recurrence and regional lymph node metastasis progression in HPV-related head and neck cancer

HPV-positive head and neck squamous cell carcinoma (HNSCC) is increasingly frequent. Management is particularly debated in the case of postsurgical high-risk features, that is, positive surgical margins and extracapsular spread (ECS). In this increasingly complex emerging framework of HNSCC treatment, representative preclinical models are needed to support future clinical trials and advances in personalized medicine. Here, we present an immunocompetent mouse model based on the implantation of mouse tonsil epithelial HPV16-E6/E7-expressing cancer cells into the submental region of the floor-of-the-mouth. Primary tumors were found to replicate the patterns of human HNSCC local invasion and lymphatic dissemination. To study disease progression after surgery, tumors were removed likely leaving behind residual disease. Surgical resection of tumors was followed by a high rate of local recurrences (>90%) within the first 2-3 weeks. While only 50% of mice had lymph node metastases (LNM) at time of primary tumor excision, all mice with recurrent tumors showed evidence of LNM. To study the consecutive steps of LNM progression and distant metastasis development, LNs from tumor-bearing mice were transplanted into naïve recipient mice. Using this approach, transplanted LNs were found to recapitulate all stages and relevant histological features of regional metastasis progression, including ECS and metastatic spread to the lungs. Altogether, we have developed an immunocompetent HPV-positive HNSCC mouse model of postsurgical local recurrence and regional and distant metastasis progression suitable for preclinical studies.

Human Papillomavirus Genome Integration and Head and Neck Cancer

We conducted a critical review of human papillomavirus (HPV) integration into the host genome in oral/oropharyngeal cancer, reviewed the literature for HPV-induced cancers, and obtained current data for HPV-related oral and oropharyngeal cancers. In addition, we performed studies to identify HPV integration sites and the relationship of integration to viral-host fusion transcripts and whether integration is required for HPV-associated oncogenesis. Viral integration of HPV into the host genome is not required for the viral life cycle and might not be necessary for cellular transformation, yet HPV integration is frequently reported in cervical and head and neck cancer specimens. Studies of large numbers of early cervical lesions revealed frequent viral integration into gene-poor regions of the host genome with comparatively rare integration into cellular genes, suggesting that integration is a stochastic event and that site of integration may be largely a function of chance. However, more recent studies of head and neck squamous cell carcinomas (HNSCCs) suggest that integration may represent an additional oncogenic mechanism through direct effects on cancer-related gene expression and generation of hybrid viral-host fusion transcripts. In HNSCC cell lines as well as primary tumors, integration into cancer-related genes leading to gene disruption has been reported. The studies have shown that integration-induced altered gene expression may be associated with tumor recurrence. Evidence from several studies indicates that viral integration into genic regions is accompanied by local amplification, increased expression in some cases, interruption of gene expression, and likely additional oncogenic effects. Similarly, reported examples of viral integration near microRNAs suggest that altered expression of these regulatory molecules may also contribute to oncogenesis. Future work is indicated to identify the mechanisms of these events on cancer cell behavior.

Nonuniform Distribution of High-risk Human Papillomavirus in Squamous Cell Carcinomas of the Oropharynx: Rethinking the Anatomic Boundaries of Oral and Oropharyngeal Carcinoma From an Oncologic HPV Perspective

The oral cavity and oropharynx have historically been viewed as a single anatomic compartment of the head and neck. The practice of combining the oral cavity and oropharynx has recently been revised, largely owing to the observation that human papillomavirus (HPV)-related carcinogenesis has a strong predilection for the oropharynx but not the oral cavity. The purpose of this study was to determine whether HPV is evenly distributed across squamous cell carcinomas of the oropharynx including those sites that do not harbor tonsillar tissues such as the soft palate. A search of the medical records of the Johns Hopkins Hospital identified 32 primary squamous cell carcinomas of the soft palate (n=31) and posterior pharyngeal wall (n=1). All were evaluated with p16 immunohistochemistry and high-risk HPV in situ hybridization (ISH) (29 by RNA ISH and 3 by DNA ISH). For comparison, we also reviewed the medical records to obtain the HPV status of patients who had undergone HPV testing of primary tonsillar carcinomas over the same time interval as part of their clinical care. High-risk HPV as detected by ISH was present in just 1 (3.1%) of the 32 oropharyngeal squamous cell carcinomas, including 1 of 2 p16-positive carcinomas. The difference in HPV detection rates between tonsillar and nontonsillar sites was significant (1/32, 3.1% vs. 917/997, 92%; P<0.0001). HPV is not frequently detected in squamous cell carcinomas arising from nontonsillar regions of the oropharynx. Indeed, squamous cell carcinomas of the soft palate more closely resemble those arising in the oral cavity than those arising in areas of the oropharynx harboring tonsillar tissue. This finding not only further sharpens our understanding of site-specific targeting by HPV, but may have practical implications regarding HPV testing and even the way the oral vault is oncologically compartmentalized to partition HPV-positive from HPV-negative cancers.

Individualized outcome prognostication for patients with laryngeal cancer

BACKGROUND

Accurate prognostication is essential to the optimal management of laryngeal cancer. Predictive models have been developed to calculate the risk of oncologic outcomes, but extensive external validation of accuracy and reliability is necessary before implementing them into clinical practice.

METHOD

Four published prognostic calculators that predict 5-year overall survival for patients with laryngeal cancer were evaluated using patient information from a prospective epidemiology study cohort (n = 246; median follow-up, 60 months) with previously untreated, stage I through IVb laryngeal squamous cell carcinoma.

RESULTS

Different calculators yielded substantially different predictions for individual patients. The observed 5-year overall survival was significantly higher than the averaged predicted 5-year overall survival of the 4 calculators (71.9%; 95% confidence interval [CI], 65%-78%] vs 47.7%). Statistical analyses demonstrated the calculators' limited capacity to discriminate outcomes for risk-stratified patients. The area under the receiver operating characteristic curve ranged from 0.68 to 0.72. C-index values were similar for each of the 4 models (range, 0.66-0.68). There was a lower than expected hazard of death for patients who received induction (bioselective) chemotherapy (hazard ratio, 0.46; 95% CI, 0.24-0.88; P = .024) or primary surgical intervention (hazard ratio, 0.43; 95 % CI, 0.21-0.90; P = .024) compared with those who received concurrent chemoradiation.

CONCLUSIONS

Suboptimal reliability and accuracy limit the integration of existing individualized prediction tools into routine clinical decision making. The calculators predicted significantly worse than observed survival among patients who received induction chemotherapy and primary surgery, suggesting a need for updated consideration of modern treatment modalities. Further development of individualized prognostic calculators may improve risk prediction, treatment planning, and counseling for patients with laryngeal cancer. Cancer 2018;124:706-16. © 2017 American Cancer Society.

Prognostic impact of leukocyte counts before and during radiotherapy for oropharyngeal cancer

Introduction

Peripheral blood count components are accessible and evidently predictive in other cancers but have not been explored in oropharyngeal carcinoma. We examine if there is an association between the use of intensity-modulated radiotherapy (IMRT) or intensity-modulated proton therapy (IMPT) and lymphopenia, as well as if there is an association between baseline neutrophilia, baseline leukocytosis and lymphocyte nadir in oropharyngeal cancer.

Materials and Methods

Analysis started with 150 patients from a previous case to case study design, which retrospectively identified adults with oropharyngeal carcinoma, 100 treated with IMRT in 2010-2012 and 50 treated with IMPT in 2011-2014. Pretreatment leukocyte, neutrophil, lymphocyte, and hemoglobin levels were extracted, as were neutrophil and lymphocyte nadir levels during radiotherapy. We retained 137 patients with recorded pre-treatment leukocyte and neutrophil levels for associated analysis and 114 patients with recorded lymphocyte levels during radiation and associated analysis. Multivariate survival analyses were done with Cox regression.

Results

The radiotherapy type (IMRT vs. IMPT) was not associated with lymphopenia (grade 3 P > .99; grade 4 P = .55). In univariate analyses, poor overall survival was associated with pretreatment neutrophilia (hazard ratio [HR] 5.58, 95% confidence interval [CI] 1.99-15.7, P = .001), pretreatment leukocytosis (HR 4.85, 95% CI 1.73-13.6, P = .003), grade 4 lymphopenia during radiotherapy (HR 3.28, 95% CI 1.14-9.44, P = .03), and possibly smoking status >10 pack-years (HR 2.88, 95% CI 1.01-8.18, P = .05), but only T status was possibly significant in multivariate analysis (HR 2.64, 95% CI 0.99-7.00, P = .05). Poor progression-free survival was associated with pretreatment leukocytosis and T status in univariate analysis, and pretreatment neutrophilia and advanced age on multivariate analysis.

Conclusions

Treatment modality did not affect blood counts during radiotherapy. Pretreatment neutrophilia, pretreatment leukocytosis, and grade 4 lymphopenia during radiotherapy were associated with worse outcomes after, but establishing causality will require additional work with increased statistical power.

A six-mRNA signature model for the prognosis of head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC), one of the most common cancers with high morbidity and mortality rates worldwide, has a poor prognosis. The transcriptome sequencing data of 500 patients with HNSCC in the TCGA dataset were assessed to find biomarkers associated with HNSCC prognosis so as to improve the prognosis of patients with HNSCC. The patients were divided into the training and testing sets. A model of six mRNAs (FRMD5, PCMT1, PDGFA, TMC8, YIPF4, ZNF324B) that could predict patient prognosis was identified in the training set using the Cox regression analysis. According to this model, the patients were divided into high-risk and low-risk groups. The Kaplan-Meier analysis showed that the high-risk group showed significantly shorter overall survival time compared with the low-risk group in both training and testing sets. The receiver operating characteristic analysis further confirmed high sensitivity and specificity for the model, which was more accurate compared with some known biomarkers in predicting HNSCC prognosis. Moreover, the model was applicable to patients of different ages, genders, clinical stages, tumor locations, smoking history, and human papillomavirus (HPV) status, as well as to microarray dataset. This model could be used as a novel biomarker for the prognosis of HNSCC and a significant tool for guiding the clinical treatment of HNSCC. The risk score acquired from the model might contribute to improving outcome prediction and management for patients with HNSCC, indicating its clinical significance.

Prognostic implications of human papillomavirus status for patients with non-oropharyngeal head and neck squamous cell carcinomas

PURPOSE

We examined overall survival in a large cohort of patients with human papillomavirus (HPV)-positive and HPV-negative non-oropharyngeal squamous cell carcinoma of the head and neck (non-OPSCC).

METHODS

Patients diagnosed with non-OPSCC and known HPV status were identified in the National Cancer Database (NCDB). Multivariate logistic regression was applied to examine factors associated with HPV status. Multivariate analysis was utilized to determine factors correlated with overall survival. Propensity score-weighted Kaplan-Meier estimation was used to adjust for confounders in survival analyses. Multiple imputation method was used for sensitivity analysis.

RESULTS

We identified 19,993 non-OPSCC patients with 5070 being positive for HPV in the NCDB. Median follow-up was 23.5 months. HPV-positive patients were more commonly male, white, with a lower comorbidity index score, presenting with T-stage <2, and N-stage ≥1. Unadjusted 3-year overall survival was 62% and 80% for HPV-negative and HPV-positive patients, respectively (p < 0.0001). On multivariate analysis, mortality was reduced for HPV-positive patients with early stage (HR = 0.68) and locally advanced disease (HR = 0.46). Adjusted 3-year overall survival was 65% for HPV-negative and 76% for HPV-positive patients (p < 0.0001). The survival advantage of HPV was maintained in all subsites and robust on sensitivity analysis.

CONCLUSIONS

Patients with HPV-positive non-OPSCC exhibit similar characteristics as HPV-positive OPSCC. Overall survival was significantly higher for patients with HPV-positive versus HPV-negative non-OPSCC. These data reveal that HPV-positive non-OPSCC represent a favorable cohort that warrants recognition in the design of future clinical trial investigation.

Prognostic Significance of Glutathione Peroxidase Levels (GPx1) in Head and Neck Cancers

INTRODUCTION

To date, no reliable prognostic biological marker for all squamous cell carcinoma located in different subsites of the head and neck region has been identified and used in daily routine. In line with our previous studies, in which we showed a role of glutathione and associated enzymes as potential biological markers, we investigated the relationship between GPx1 and prognosis of head and neck squamous cell carcinoma.

METHODS

The association between GPx1 and patient and tumor related factors were investigated in 87 pretreatment biopsies from head and neck cancer patients treated by (chemo)radiation. Moreover, the influence of GPx1 expression on outcome parameters was assessed.

RESULTS

A significant difference was found in the T-stage between the low and high-expressing GPx1 groups. About 75% of the T3-T4 tumors were considered GPx1 low-expressing tumors, while low GPx1 expression was only seen in 25% of the T1-T2 tumors. There was also a significant difference found between the groups when looking at the different tumor sites. Local control, locoregional control, disease-free survival, and overall survival were the same in both groups. All these results indicate that GPx1 expression does not influence the radiotherapy response nor survival.