Proton Treatment Suppresses Exosome Production in Head and Neck Squamous Cell Carcinoma

Proton therapy (PT) is emerging as an effective and less toxic alternative to conventional X-ray-based photon therapy (XRT) for patients with advanced head and neck squamous cell carcinomas (HNSCCs) owing to its clustered dose deposition dosimetric characteristics. For optimal efficacy, cancer therapies, including PT, must elicit a robust anti-tumor response by effector and cytotoxic immune cells in the tumor microenvironment (TME). While tumor-derived exosomes contribute to immune cell suppression in the TME, information on the effects of PT on exosomes and anti-tumor immune responses in HNSCC is not known. In this study, we generated primary HNSCC cells from tumors resected from HNSCC patients, irradiated them with 5 Gy PT or XRT, and isolated exosomes from cell culture supernatants. HNSCC cells exposed to PT produced 75% fewer exosomes than XRT- and non-irradiated HNSCC cells. This effect persisted in proton-irradiated cells for up to five days. Furthermore, we observed that exosomes from proton-irradiated cells were identical in morphology and immunosuppressive effects (suppression of IFN-γ release by peripheral blood mononuclear cells) to those of photon-irradiated cells. Our results suggest that PT limits the suppressive effect of exosomes on cancer immune surveillance by reducing the production of exosomes that can inhibit immune cell function.

Rapid purification and multiparametric characterization of circulating small extracellular vesicles utilizing a label-free lab-on-a-chip device

Nano-scale extracellular vesicles are lipid-bilayer delimited particles that are naturally secreted by all cells and have emerged as valuable biomarkers for a wide range of diseases. Efficient isolation of small extracellular vesicles while maintaining yield and purity is crucial to harvest their potential in diagnostic, prognostic, and therapeutic applications. Most conventional methods of isolation suffer from significant shortcomings, including low purity or yield, long duration, need for large sample volumes, specialized equipment, trained personnel, and high costs. To address some of these challenges, our group has reported a novel insulator-based dielectrophoretic device for rapid isolation of small extracellular vesicles from biofluids and cell culture media based on their size and dielectric properties. In this study, we report a comprehensive characterization of small extracellular vesicles isolated from cancer-patients' biofluids at a twofold enrichment using the device. The three-fold characterization that was performed using conventional flow cytometry, advanced imaging flow cytometry, and microRNA sequencing indicated high yield and purity of the isolated small extracellular vesicles. The device thus offers an efficient platform for rapid isolation while maintaining biomolecular integrity.

Small extravesicular microRNA in head and neck squamous cell carcinoma and its potential as a liquid biopsy for early detection

BACKGROUND

The objective was to assess secretion of small extracellular vesicular microRNA (exo-miRNA) in head and neck squamous cell carcinoma (HNSCC) according to human papillomavirus (HPV) status, and determine the translational potential as a liquid biopsy for early detection.

METHODS

This study employed a combination of cell culture and case-control study design using archival pretreatment serum. Small extracellular vesicles (sEV) were isolated from conditioned culture media and human serum samples via differential ultracentrifugation. miRNA-sequencing was performed on each sEV isolate.

RESULTS

There were clear exo-miRNA profiles that distinguished HNSCC cell lines from nonpathologic oral epithelial control cells. While there was some overlap among profiles across all samples, there were apparent differences in exo-miRNA profiles according to HPV-status. Importantly, differential exo-miRNA profiles were also apparent in serum from early-stage HNSCC cases relative to cancer-free controls.

CONCLUSIONS

Our findings indicate that exo-miRNA are highly dysregulated in HNSCC and support the potential of exo-miRNA as biomarkers for HNSCC.

Stable methylation loci are associated with systolic blood pressure in a Croatian island population

Background: The objective was to identify stable and dynamic DNA methylation loci associated with cardiometabolic traits among an adult population from the Croatian island of Hvar. Materials & methods: An epigenome-wide association study was conducted using peripheral blood longitudinally collected at two time points 10 years apart via Infinium MethylationEPIC beadarray (n = 112). Stable and dynamic loci were identified using linear mixed models. Associations between cardiometabolic traits and loci were assessed using linear models. Results: 22 CpG loci were significantly associated with systolic blood pressure. Twenty were stable and two were dynamic. Conclusion: Multiple genes may be involved in the determination of systolic blood pressure level via stable epigenetic programming, potentially established earlier in life.

DNA methylation-derived systemic inflammation indices and their association with oropharyngeal cancer risk and survival

BACKGROUND

Head and neck squamous cell carcinomas are associated with systemic inflammation (SI). We evaluated whether DNA methylation-derived SI (mdSI) indices are associated with oropharyngeal cancer risk and survival.

METHODS

Ninety-four oropharyngeal squamous cell carcinoma (OPSCC) cases and 57 controls with DNA methylation data were included. Logistic regression analysis and survival analysis were performed to test the association of mdSI indices with OPSCC risk and survival.

RESULTS

Higher methylation-derived neutrophil-to-lymphocyte ratio (mdNLR) was associated with increased risk of OPSCC (OR = 1.21, 95%CI: 1.11-1.40) while no association was found with methylation-derived lymphocyte-to-monocyte ratio (mdLMR). For 5-year overall survival, higher mdLMR was significantly associated with decreased risk of death (HR = 0.25, 95%CI: 0.10-0.64) while the converse was observed for mdNLR (HR = 2.48, 95%CI: 1.04-5.92).

CONCLUSION

We observed an association between mdSI indices and OPSCC risk and 5-year overall survival. It is possible to use mdLMR as an independent prognostic factor for OPSCC.

Human Papillomavirus and Survival of Sinonasal Squamous Cell Carcinoma Patients: A Systematic Review and Meta-Analysis

Simple Summary

Human papillomavirus (HPV) has been associated with multiple cancers in the anogenital and upper aerodigestive tracts. In the head and neck region, HPV-positive cancers are common in oropharynx, with rising incidence and a well-established association with more favorable patient outcomes. However, the relationship with prognosis of sinonasal squamous cell carcinoma (SNSCC) has been much less often studied and is presently unclear. To better elucidate this relationship, we performed a systematic review and meta-analysis of the biomedical literature to determine the aggregate effect across studies. In doing so, we observed significantly better overall survival associated with HPV-positive SNSCC. Therefore, we conclude that HPV testing may be useful for determining patient prognosis and potentially guiding treatment decisions.

Abstract

Human papillomavirus (HPV) is detectable in a subset of sinonasal squamous cell carcinoma (SNSCC), but the impact on patient outcomes is presently unclear due to a modest number of studies with limited statistical power. Therefore, we conducted a systematic review and meta-analysis to better clarify this relationship. A PubMed search was conducted to identify all studies reporting on overall (OS) or disease-free survival (DFS) for SNSCC by HPV status. Hazard ratios (HR) and corresponding 95% confidence intervals (CI) were extracted or, when not provided, indirectly estimated from each manuscript. Summary survival curves for 5-year OS and estimating survival probability by HPV status at pre-specified time intervals from study-specific Kaplan-Meier curves generated 2-year DFS. Log HRs and log CIs were combined across studies to generate summary estimates and a corresponding 95% CIs for OS and DFS. We identified ten unique studies reporting on OS and four for DFS. We observed a significant association between HPV and OS (summary HR = 0.51, 95% CI: 0.38–0.70) with relatively low heterogeneity between studies. These results indicate that HPV is a significant predictor of more favorable survival for SNSCC, and thus may be a useful biomarker for prognostication and, potentially, treatment modulation.

Comparability of the small RNA secretome across human biofluids concomitantly collected from healthy adults

Small extracellular vesicles (sEV) are nano-sized (40–150 nm), membrane-encapsulated vesicles that are released by essentially all cells into the extracellular space and function as intercellular signaling vectors through the horizontal transfer of biologic molecules, including microRNA (miRNA) and other small non-coding RNA (ncRNA), that can alter the phenotype of recipient cells. sEV are present in essentially all extracellular biofluids, including serum, urine and saliva, and offer a new avenue for discovery and development of novel biomarkers of various disease states and exposures. The objective of this study was to systematically interrogate similarities and differences between sEV ncRNA derived from saliva, serum and urine, as well as cell-free small ncRNA (cf-ncRNA) from serum. Saliva, urine and serum were concomitantly collected from 4 healthy donors to mitigate potential bias that can stem from interpersonal and temporal variability. sEV were isolated from each respective biofluid, along with cf-RNA from serum. sEV were isolated from the respective biofluids via differential ultracentrifugation with a 30% sucrose cushion to minimize protein contamination. Small RNA-sequencing was performed on each sample, and cluster analysis was performed based on ncRNA profiles. While some similarities existed in terms of sEV ncRNA cargo across biofluids, there are also notable differences in ncRNA class and ncRNA secretion, with sEV in each biofluid bearing a unique ncRNA profile, including major differences in composition by ncRNA class. We conclude that sEV ncRNA cargo varies according to biofluid, so thus should be carefully selected and interpreted when designing or contrasting translational or epidemiological studies.

Firefighter occupation is associated with increased risk for laryngeal and hypopharyngeal squamous cell carcinoma among men from the Greater Boston area

OBJECTIVE

Firefighters are exposed to a wide variety of carcinogens during the line of duty, including several associated with head and neck cancer. Existing studies assessing head and neck cancer risk with firefighting have predominately included occupational cohorts or registry data, which are limited by inability to adjust for smoking and alcohol consumption-major risk factors for head and neck cancer. Our objective was to assess the risk of head and neck cancer among men with an occupational history as a firefighter.

METHODS

This work was conducted using male subjects from a large population-based case-control study of head and neck cancer from the greater Boston area using self-reported occupational history (718 cases and 905 controls).

RESULTS

An occupational history as a firefighter was reported for 11 cases and 14 controls. Although no significant association was observed overall, we observed substantial increased risk for hypopharyngeal and laryngeal squamous cell carcinoma among professional municipal firefighters who had a light or no smoking history (OR=8.06, 95% CI 1.74 to 37.41), with significantly increasing risk per decade as a firefighter (OR=2.10, 95% CI 1.06 to 4.14).

CONCLUSION

Professional municipal firefighters may be at increased risk for hypopharyngeal and laryngeal squamous cell carcinoma due to carcinogenic exposures encountered during the line of duty.

Rapid and label-free isolation of small extracellular vesicles from biofluids utilizing a novel insulator based dielectrophoretic device

Exosomes are nano-scale membrane-encapsulated vesicles produced by the majority of cells and have emerged as a rich source of biomarkers for a wide variety of diseases. Although many approaches have been developed for exosome isolation from biofluids, most of them have substantial shortcomings including long processing time, inefficiency, high cost, lack of specificity and/or surface marker-dependency. To address these issues, here we report a novel insulator-based dielectrophoretic (iDEP) device predicated on an array of borosilicate micropipettes to rapidly isolate exosomes from conditioned cell culture media and biofluids, such as plasma, serum, and saliva. The device is capable of exosome isolation from small sample volumes of 200 μL within 20 minutes under a relatively low (10 V cm-1) direct current (DC). This device is easy to fabricate thus, no cleanroom facility and expensive equipment are needed. Therefore, the iDEP device offers a rapid and cost-effective strategy for exosome isolation from biofluids in timely manner while maintaining the yield and purity.

Abstract 5038: Chrysotile asbestos fibers in tissue adjacent to laryngeal squamous cell carcinoma in cases with a history of occupational asbestos exposure

Asbestos describes a group of naturally occurring fibrous silicate mineral compounds. Its use dates back thousands of years but became widespread in the late 19th century through the late 20th century due to its favorable industrial properties, including its strength, flexibility and thermal properties, with peak use in the United States occurring in the 1970s. Asbestos has been associated with a number of chronic respiratory diseases, including malignancy, and was first linked to mesothelioma and lung cancer in the early to mid part of the 20th century. Despite the known health risks, asbestos is not universally banned and is still in use in many countries (including the United States), with an estimated 125 million occupationally-exposed individuals worldwide. In addition to mesothelioma and lung cancer, asbestos has also been implicated as a risk factor for squamous cancers involving the upper airway, in particular laryngeal and pharyngeal carcinoma, as indicated by recent meta-analyses; however, evidence for the latter associations is based solely on epidemiologic data from observational studies. The primary objective of this work was to attempt to strengthen the evidence via empirical demonstration of persistent asbestos fibers embedded in the tissue surrounding the tumor, thus providing a more definitive biological link between exposure and disease. Six HPV-negative laryngeal and pharyngeal squamous cell carcinoma cases were selected from a large population-based case-control study of head and neck cancer, plus one case with no occupational exposure history as a control. Briefly, detailed occupational history was available for 1,056 head and neck cancer cases enrolled through major teaching hospitals located in Boston, Massachusetts. Occupational data was reviewed to identify those with an occupational history of asbestos exposure. Tissue cores were obtained from adjacent non-neoplastic tissue in tumor blocks from the initial primary tumor resection from a subset of 6 cases with a history of occupational-asbestos exposure and 1 case with no reported occupational exposure (control). A count of asbestos fibers >5um was performed on the cores from each case at Duke University using a scanning electron microscope equipped with an energy dispersive x-ray analyzer (EDXA). Despite the low volume of input tissue, chrysotile asbestos fibers were identified in 3/6 of evaluated cases with a history of occupational asbestos exposure; all 3 cases had tumors originating in the larynx. This is the first study to demonstrate the presence of asbestos fibers in the larynx of cases with laryngeal squamous cell carcinoma, adding an additional line of physical evidence implicating asbestos as an etiologic factor for laryngeal squamous cell carcinoma.

Citation Format: Stephanie K. Wronkiewicz, Victor Roggli, Damaris Kuhnell, Rondi A. Butler, Karl T. Kelsey, Scott M. Langevin. Chrysotile asbestos fibers in tissue adjacent to laryngeal squamous cell carcinoma in cases with a history of occupational asbestos exposure [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5038.

Comprehensive mapping of the methylation landscape of 16 CpG-dense regions in oral and pharyngeal squamous cell carcinoma

Aim: The goal of this study was to comprehensively interrogate and map DNA methylation across 16 CpG-dense regions previously associated with oral and pharyngeal squamous cell carcinoma (OPSCC). Materials & methods: Targeted multiplex bisulfite amplicon sequencing was performed on four OPSCC cell lines and primary non-neoplastic oral epithelial cells. Real-time quantitative polymerase chain reaction (RT-qPCR) was performed for a subset of associated genes. Results: There was clear differential methylation between one or more OPSCC cell lines and control cells for the majority of CpG-dense regions. Conclusion: Targeted multiplex bisulfite amplicon sequencing allowed us to efficiently map methylation across the entire region of interest with a high degree of sensitivity and helps shed light on novel differentially methylated regions that may have value as biomarkers of OPSCC.

Balancing yield, purity and practicality: a modified differential ultracentrifugation protocol for efficient isolation of small extracellular vesicles from human serum

Ultracentrifugation remains the gold standard for isolation of small extracellular vesicles (sEV), particularly for cancer applications. The objective of this study was to determine if a widely used ultracentrifugation protocol for isolation of serum sEV could be modified to reduce the number of ultracentrifugation cycles and increase efficiency, while maintaining equal or better sample purity and yield. Serum was obtained from two healthy subjects. sEVs were isolated from 1 mL aliquots using three different ultracentrifugation protocols. Co-isolation of RNA carrier protein was assessed by performing Western blots for ApoA-I, ApoB, and Ago2. Small RNA-sequencing was performed on the sEV isolates, and differential detection of small ncRNA was compared across isolation protocols. Reduction from three- to two-ultracentrifuge cycles with no sucrose cushion resulted in a much higher sEV yield but also had the highest levels of lipoprotein and Ago2 contamination. However, the two-ultracentrifugation cycle protocol that incorporated a 30% sucrose cushion into the first cycle resulted in slightly higher sEV yields with lower levels of protein contamination compared to the lengthier three-ultracentrifugation cycle approach, therefore presenting a more efficient alternative approach for isolation of serum sEVs. It was also notable that there were some differences in sEV ncRNA cargo according to protocol, although it was less than expected given the differences in co-isolated RNA carrier proteins. Our results suggest that use of the modified serum sEV isolation protocol with two ultracentrifugation cycles and incorporating a 30% sucrose cushion offers a more efficient approach in terms of efficiency and purity.

Minimal information for studies of extracellular vesicles 2018 (MISEV2018): a position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines

The last decade has seen a sharp increase in the number of scientific publications describing physiological and pathological functions of extracellular vesicles (EVs), a collective term covering various subtypes of cell-released, membranous structures, called exosomes, microvesicles, microparticles, ectosomes, oncosomes, apoptotic bodies, and many other names. However, specific issues arise when working with these entities, whose size and amount often make them difficult to obtain as relatively pure preparations, and to characterize properly. The International Society for Extracellular Vesicles (ISEV) proposed Minimal Information for Studies of Extracellular Vesicles ("MISEV") guidelines for the field in 2014. We now update these "MISEV2014" guidelines based on evolution of the collective knowledge in the last four years. An important point to consider is that ascribing a specific function to EVs in general, or to subtypes of EVs, requires reporting of specific information beyond mere description of function in a crude, potentially contaminated, and heterogeneous preparation. For example, claims that exosomes are endowed with exquisite and specific activities remain difficult to support experimentally, given our still limited knowledge of their specific molecular machineries of biogenesis and release, as compared with other biophysically similar EVs. The MISEV2018 guidelines include tables and outlines of suggested protocols and steps to follow to document specific EV-associated functional activities. Finally, a checklist is provided with summaries of key points.

Differential expression and prognostic value of long non-coding RNA in HPV-negative head and neck squamous cell carcinoma

BACKGROUND

Long non-coding RNA (lncRNA) has emerged as a new avenue of interest due to its various biological functions in cancer. Abnormal expression of lncRNA has been reported in other malignancies but has been understudied in head and neck squamous cell carcinoma (HNSCC).

METHODS

The lncRNA expression was interrogated via quantitative real-time polymerase chain reaction (qRT-PCR) array for 19 human papillomavirus (HPV)-negative HNSCC tumor-normal pairs. The Cancer Genome Atlas (TCGA) was used to validate these results. The association between differentially expressed lncRNA and survival outcomes was analyzed.

RESULTS

Differential expression was validated for 5 lncRNA (SPRY4-IT1, HEIH, LUCAT1, LINC00152, and HAND2-AS1). There was also an inverse association between MEG3 expression (not significantly differentially expressed in TCGA tumors but highly variable expression) and 3-year recurrence-free survival (RFS).

CONCLUSION

We identified and validated differential expression of 5 lncRNA in HPV-negative HNSCC. Low MEG3 expression was associated with favorable 3-year RFS, although the significance of this finding remains unclear.

Abstract 26: Exosomal microRNA as salivary biomarkers of head and neck squamous cell carcinoma

Head and neck cancer is the 10th most common cancer overall and 5th most common among men in the United States, the vast majority of which are squamous cell carcinoma (HNSCC). Despite approximately two-thirds of cases being diagnosed at an advanced stage, the only routine screening approach currently in widespread use is visual inspection and palpation, which is provided by dentists and clinicians on an opportunistic basis, lacks sensitivity, and varies according to the skill of the clinician. This underscores the urgent and compelling need for establishment of novel and effective biomarkers to facilitate early detection. Exosomes may offer a new avenue for discovery and development of novel biomarkers of HNSCC. These nanosized (40-150 nm), membrane-encapsulated vesicles are released by both normal and malignant cells into the extracellular space and function as intercellular signaling vectors through the horizontal transfer of biologic molecules, including microRNA (miRNA), which can affect the phenotype of recipient cells. Importantly, exosomes are present in essentially all extracellular biofluids, including saliva, and thus can readily be collected by noninvasive means. Through previous cell culture work, we observed striking differences in exosomal miRNA secreted by HNSCC cells relative to healthy oral epithelial cells, with a high degree of overlap in exosomal miRNA profiles across HNSCC cell lines. Although salivary exosomes have been theorized to be a potentially powerful biomarker source for HNSCC, there has been an extreme paucity of work conducted in this arena. To begin to address this question, we conducted a small pilot study in which we collected 2-mL whole-saliva samples from 5 HNSCC cases (collected prior to initiation of treatment) and 5 cancer-free controls. Exosomes were isolated from each saliva sample via differential ultracentrifugation, and total RNA was extracted for miRNA-sequencing (miRNA-seq), which was performed by the University of Cincinnati Genomics, Epigenomics & Sequencing Core (GESC). The number of reads for each sample during miRNA-seq ranged from 1.6 million to 27.4 million reads (median = 12.4 million). After aligning the reads to all human miRNA sequences catalogued in miRBase, there were a total of 1,334 mature miRNA transcripts detected across samples, with 307 transcripts (12%) detected solely in salivary exosomes from cases. Moreover, despite the small sample size of the pilot study, we observed significant differential exosomal secretion of miR-10b-5p (p = 0.006), with transcripts present at relatively high levels in salivary exosomes from 3 of the 5 cases but none detected in those from the 5 controls. We also preliminarily assessed the translational potential of 8 miRNA transcripts that were solely and universally expressed by our HNSCC cell lines (i.e. not secreted by healthy oral epithelial cells) in our previous cell culture work using the salivary exosome miRNA-seq data for the 5 cases and 5 controls. All 8 transcripts were detected in salivary exosomes obtained from the 5 HNSCC cases. In particular, miR-486-5p and miR-486-3p showed considerable promise, with 40% of cases expressing drastically higher levels of these transcripts relative to controls. When either miR-486-5p or miR-486-3p was combined with miR-10b-5p, the substantial separation of these markers could clearly distinguish 80% (4/5) of the HNSCC cases from controls. These findings demonstrate the potential of salivary miRNA as biomarkers of HNSCC and highlight the necessity of further workup and validation in full-scale studies involving human saliva.

Citation Format: Scott M. Langevin, Damaris Kuhnell, Xiang Zhang, Trisha M. Wise-Draper, Keith A. Casper. Exosomal microRNA as salivary biomarkers of head and neck squamous cell carcinoma [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Optimizing Survival and Quality of Life through Basic, Clinical, and Translational Research; April 23-25, 2017; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(23_Suppl):Abstract nr 26.

Abstract 1797: EGFR as a marker for head and neck squamous cell carcinoma-derived small extracellular vesicles

Head and neck cancer will account for an estimated 61,760 new cancer cases and 13,190 cancer-related deaths in the United States in 2016, the majority of which (> 90%) will be squamous cell carcinoma (HNSCC). The prognosis for HNSCC is relatively poor, with an overall 5-year survival around 60%, and the outlook worsens with increasing stage at diagnosis, which is problematic since about two-thirds of patients present with advanced stage disease. This underscores the urgent need for discovery, development and translation of novel biomarkers to facilitate early detection of HNSCC and bolster the chance for positive patient outcomes. Exosomes are nano-sized (40-150 nm) membrane-encapsulated vesicles that may offer a new avenue for discovery and development of novel HNSCC biomarkers. However, they are released by essentially all cells, both normal and malignant, into the extracellular space, resulting in a noisy environment in biofluids from the perspective of biomarker measurement. As such, a membrane-bound surface marker that allows for enrichment for cancer-derived exosomes in patient samples would provide a clear benefit. Epidermal growth factor receptor (EGFR), which belongs to the ErbB/HER family of receptor tyrosine kinases, localizes to the plasma membrane and is over-expressed in as much as 90% of HNSCC tumors. Therefore, we hypothesized that EGFR will be over-represented on membranes of HNSCC-derived exosomes and thus may offer utility as a surface marker for detection and/or enrichment. To test this, we cultured an HNSCC cell line that over-expresses EGFR (FaDu), EGFR-deficient SW620 colorectal adenocarcinoma cells, and primary human oral epithelial cells pooled from 3 healthy donors. Cells were cultivated in supplier-recommended media with 10% fetal bovine serum (FBS) that was super-depleted of exosomes via 18 hour ultracentrifugation at 100,000g and 1% penicillin/streptomycin at 37°C with 5% CO2 in 150 cm2 flasks with 25mL media. After reaching 80-90% confluence, media was harvested, and exosomes were isolated and purified via differential ultracentrifugation. Exosome isolates were whole-mounted on carbon grids, Immuno-Gold labeled with anti-EGFR, and imaged on a JEOL JEM-1230 transmission electron microscope (Immuno-EM); anti-nucleoporin 153 (NUP-153), which localizes to the nucleus, was used as a negative control. Immuno-EM images indicate abundant EGFR expression on exosomes secreted by FaDu HNSCC cells, but EGFR is not detectable on the exosomes secreted by the oral epithelial cells from healthy donors. These results indicate that EGFR may offer utility for enrichment for HNSCC-derived exosomes in human biofluid isolates using magnetic beads or flow cytometry.

Citation Format: Jenna A. Dombroski, Damaris Kuhnell, Susan Kasper, Scott M. Langevin. EGFR as a marker for head and neck squamous cell carcinoma-derived small extracellular vesicles [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1797. doi:10.1158/1538-7445.AM2017-1797

Immune Response to HPV16 E6 and E7 Proteins and Patient Outcomes in Head and Neck Cancer

Importance

Pathology-based measures of human papillomavirus (HPV) status are routinely obtained in the care of head and neck cancer and are clearly associated with patient outcome for cancers of the oropharynx. However, it is unclear if HPV status is of high value for cancers of the larynx and oral cavity. In addition, it is possible to assess HPV infection using serology-based methods; however, the suitability of this pathology-independent measure for predicting patient outcome in head and neck cancer is unknown.

Objective

To investigate whether immunologic response to HPV16 is associated with patient survival across anatomic sites, independent of smoking and drinking history.

Design, Setting, and Participants

This was a population-based study of 1054 patients with head and neck cancer in the greater Boston, Massachusetts, area (1999-2003, 2006-2011).

Main Outcomes and Measures

All-cause survival in relation to HPV16 E6 and E7 seropositivity.

Results

The 1054 patients reflected the demographics of those treated in this timeframe (75% male; mean age, 59 years). Seropositivity was very strongly associated with improved survival overall (hazard ratio HR], 0.33; 95% CI, 0.24-0.45; P < .001), with no evidence that the magnitude of immune response, as assessed by titer levels, effected outcome. Seropositivity was associated with improved patient survival across all head and neck cancer sites: HR for oropharynx cancer, 0.26; 95% CI, 0.18-0.39; for oral cavity cancer, 0.45; 95% CI, 0.18-0.80; and for larynx cancer, 0.29; 95% CI, 0.10-0.85. In addition, the associations with seropositivity were similar across smoking and/or drinking exposure groups: HRfor low exposure, 0.52; 95% CI, 0.20-1.36; for moderate exposure, 0.42; 95% CI, 0.25-0.70; for heavy exposure, 0.51; 95% CI, 0.36-0.73. In a subset of 162 patients with both HPV serology and p16 immunohistochemical (IHC) measures available, both measures were similarly associated with survival in the oropharynx (HR for serology, 0.16; 95% CI, 0.03-0.47; for p16 measures, 0.16; 95% CI, 0.03-0.46), whereas only serology was associated with outcome when considering all head and neck cancer cases (HR for serology,0.49; 95% CI, 0.23-1.04; for p16, 0.65; 95% CI, 0.30-1.42).

Conclusions and Relevance

Collectively, these data suggest that a positive serologic response to HPV16 oncoproteins may be the best approach to assess HPV-disease for clinical outcome because it is associated with survival for all types of disease and is a marker that is not dependent on pathology material.

Abstract 961: Comprehensive catalog of culture-derived exosomal microRNA cargo from 4 discrete head and neck carcinoma cell lines

Background: Exosomes are nano-sized (40-100 nm), membrane encapsulated vesicles that are released by cells into the extracellular space and function as intercellular signaling vectors through the horizontal transfer of biologic molecules, including non-coding RNA. MicroRNA (miRNA) are small (18-25 nucleotides in length), evolutionarily conserved, non-coding RNA molecules that are involved in regulation of gene expression in essentially all eukaryotic organisms through post-transcriptional degradation and translational inhibition of messenger RNA (mRNA). The purpose of this study was to catalog exosomal miRNA cargo that are differentially secreted from head and neck squamous cell carcinoma (HNSCC) cells in vitro using Next Generation miRNA-sequencing.

Methods: We obtained 4 commercially available HNSCC cell lines: (1) H413 (female, buccal); (2) Detroit 562 (female, pharynx metastatic to pleura); (3) FaDu (male, hypopharynx) and (4) Cal 27 (male, tongue). We additionally obtained HGEPp primary human gingival epithelial cells (pooled from 3 healthy female donors) for comparison. Cells were cultivated in supplier-recommended media with 10% fetal bovine serum (FBS) that was super-depleted of exosomes via 18 hour ultracentrifugation at 100,000g and 1% penicillin/streptomycin at 37°C with 5% CO2 in 150 cm2 flasks with 25mL media. To achieve adequate volume for exosome isolation (50mL), cells were cultured in 2-pair sets of flasks in triplicate (6 flasks total per cell line). Media was collected when cells reached 80-90% confluence. Exosomes were isolated and purified from exosome-depleted cell culture media by differential ultracentrifugation and the presence of purified exosomes was verified via nanoparticle tracking analysis (NTA) using a NanoSight NS300 instrument. Total RNA was extracted from each exosome pellet using the miRNeasy Micro kit, and Next Generation miRNA-sequencing was subsequently performed by the University of Cincinnati Genomics, Epigenomics and Sequencing Core (Cincinnati, OH) using the Illumina HiSeq platform. Differential exosomal miRNA secretion was assessed between each HNSCC cell line and the non-pathologic gingival epithelial control cells, adjusting for false-discovery rate using the Benjamini and Hochberg method.

Results: We observed 93 miRNA transcripts that were differentially secreted (Q &lt; 0.05) in exosomes derived from at least one of the HNSCC cell lines relative to the non-pathologic epithelial control cells; 23 miRNA transcripts were differentially secreted by all 4 cell-lines.

Conclusions: This provides evidence for differential secretion of miRNA in HNSCC-derived exosomes. These exosomal miRNA warrant further evaluation as potential biomarkers for HNSCC.

Citation Format: Scott M. Langevin, Damaris Kuhnell, Tess L. Parry, Jacek Biesiada, Xiang Zhang, Mario Medvedovic, Susan Kasper. Comprehensive catalog of culture-derived exosomal microRNA cargo from 4 discrete head and neck carcinoma cell lines. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 961.

CpG island methylation profile in non-invasive oral rinse samples is predictive of oral and pharyngeal carcinoma

BACKGROUND

There are currently no screening tests in routine use for oral and pharyngeal cancer beyond visual inspection and palpation, which are provided on an opportunistic basis, indicating a need for development of novel methods for early detection, particularly in high-risk populations. We sought to address this need through comprehensive interrogation of CpG island methylation in oral rinse samples.

METHODS

We used the Infinium HumanMethylation450 BeadArray to interrogate DNA methylation in oral rinse samples collected from 154 patients with incident oral or pharyngeal carcinoma prior to treatment and 72 cancer-free control subjects. Subjects were randomly allocated to either a training or a testing set. For each subject, average methylation was calculated for each CpG island represented on the array. We applied a semi-supervised recursively partitioned mixture model to the CpG island methylation data to identify a classifier for prediction of case status in the training set. We then applied the resultant classifier to the testing set for validation and to assess the predictive accuracy.

RESULTS

We identified a methylation classifier comprised of 22 CpG islands, which predicted oral and pharyngeal carcinoma with a high degree of accuracy (AUC = 0.92, 95 % CI 0.86, 0.98).

CONCLUSIONS

This novel methylation panel is a strong predictor of oral and pharyngeal carcinoma case status in oral rinse samples and may have utility in early detection and post-treatment follow-up.

Occupational asphalt is not associated with head and neck cancer

BACKGROUND

Epidemiologic studies that evaluate the relationship between occupational asphalt exposure and head and neck cancer have had a limited ability to control for known risk factors such as smoking, alcohol and human papillomavirus (HPV).

AIMS

To better elucidate this relationship by including known risk factors in a large case-control study of head and neck squamous cell carcinoma (HNSCC) from the greater Boston area.

METHODS

We analysed the relationship between occupational asphalt exposure and HNSCC among men in the Greater Boston area of Massachusetts. Analyses were conducted using unconditional multivariable logistic regression, performed with adjustments for age, race, education, smoking, alcohol consumption and HPV serology.

RESULTS

There were 753 cases and 913 controls. No associations between HNSCC and occupational asphalt exposure (neither among ever-exposed nor by occupational duration) were observed for exposures in any occupation or those restricted to the construction industry. We also observed no associations in subgroup analyses of never-smokers and ever-smokers. Adjusting for known risk factors further reduced the estimated effect of asphalt exposure on HNSCC risk.

CONCLUSIONS

We found no evidence for an association between occupational asphalt exposure and HNSCC. The null findings from this well-controlled analysis could suggest that the risk estimates stemming from occupational cohort studies may be overestimated due to uncontrolled confounding and enhance the literature available for weighing cancer risk from occupational exposure to bitumen.

Human papillomavirus serology and tobacco smoking in a community control group

Background

HPV infection is an established risk factor for oropharyngeal cancer, and it has been proposed that cigarette smoking may potentiate HPV infection in the oral epithelium. We sought to test the hypothesis that cigarette smoking increases HPV infection in an HPV16 serology study of cancer-free individuals.

Methods

Subjects were participants in a risk factor study for head and neck cancer, and were required to have no prior history of either HNSCC or any other cancer. Tobacco use and other risk factor data were gathered through interviewer-assisted questionnaires, while serology was conducted in a blinded fashion using a glutathione S-transferase capture enzyme-linked immunosorbent assay (ELISA) to detect antibodies against HPV16 L1, E1, E2, E4, E6 and E7 proteins. The differences in tobacco use by HPV serology were evaluated by ANOVA; and the reported odds ratios and 95% confidence intervals were determined by using unconditional logistic regression.

Results

We found no overall association of HPV16 serological markers with smoking. However, when the data were stratified by median age, smoking was positively associated with seropositivity for the HPV16 L1 capsid antigen in the younger controls while the older controls were less likely to be HPV16 L1 positive if they smoked (p_interaction < 0.002). There was no similar association of smoking and age with serological response to the early proteins (i.e E6, E7).

Conclusions

Exposure to HPV16 capsid protein (L1) is increased among relatively younger adults who smoke and diminished among older smokers. However, this pattern is not accompanied by a differential susceptibility for active infection (as determined by the early gene proteins such as E6 and E7) among young and older smokers.

Epigenetics of lung cancer

Lung cancer is the leading cause of cancer-related mortality in the United States. Epigenetic alterations, including DNA methylation, histone modifications, and noncoding RNA expression, have been reported widely in the literature to play a major role in the genesis of lung cancer. The goal of this review is to summarize the common epigenetic changes associated with lung cancer to give some clarity to its etiology, and to provide an overview of the potential translational applications of these changes, including applications for early detection, diagnosis, prognostication, and therapeutics.

Abstract 279: Head and neck squamous cell carcinoma risk among asphalt workers from the greater Boston area

Asphalt (or bitumen) is produced from the distillation of crude petroleum and used in road surfacing, roofing, and waterproofing applications. When heated during application, asphalt emits a mixture of fumes, vapors and solid particulates, including carcinogens such as polycyclic aromatic hydrocarbons (PAH), which come in direct contact with the epithelium of the upper aerodigestive tract upon inhalation. Therefore, chronic exposure among asphalt workers could potentially result in elevated risk for upper aerodigestive tract cancers. There are presently no case-control studies reporting on this relationship. There is limited evidence of an association from occupational cohort studies, although these studies offer poor control for important, potentially confounding factors, such as smoking or alcohol consumption. Thus, we have investigated the association between occupational exposure to asphalt and head and neck squamous cell carcinoma (HNSCC) in a large population-based case-control study from the greater Boston area. Occupational asphalt exposure data was available for 951 incident HNSCC cases and 1193 cancer-free control subjects, matched on age (+/- 3 years), sex, and town or neighborhood of residence. Study subjects completed a self-administered questionnaire that provided detailed data on occupational history, sociodemographics and personal characteristics, and alcohol and tobacco use. Asphalt exposure was dichotomized as exposed or never exposed based on self-reported occupation data, and also by total duration of occupational exposure to asphalt. Multivariable unconditional logistic regression was used to assess the association between asphalt exposure and HNSCC, overall and by primary tumor site. A total of 140 (14.7%) cases and 145 (12.2%) controls reported an occupational exposure to asphalt. There was a significant crude association between asphalt exposure and pharyngeal cancer (crude OR = 1.47, 95% CI: 1.09-2.00) and elevated point estimates (although non-significant) for HNSCC overall and in the larynx. However, both the magnitude and significance eroded after adjusting for age, sex, smoking, and alcohol consumption. Similarly, we observed a borderline significant dose-response between occupational duration and crude HNSCC risk, overall and for the pharynx and larynx, but, again, the magnitude and (borderline) significance eroded following adjustment for confounding factors. Since cigarettes are a substantial source of PAH exposure among smokers, we repeated the analysis restricted to never-smokers but did not observe any significant association. We found no evidence for an association between asphalt work and HNSCC risk. These observations suggest that the risk estimates for HNSCC among asphalt workers provided by occupational cohort studies may be overstated due to uncontrolled confounding.

Citation Format: Scott M. Langevin, Melissa Eliot, Michael D. McClean, Karl T. Kelsey. Head and neck squamous cell carcinoma risk among asphalt workers from the greater Boston area. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 279. doi:10.1158/1538-7445.AM2014-279

Novel DNA methylation targets in oral rinse samples predict survival of patients with oral squamous cell carcinoma

OBJECTIVES

The objective of this study was to identify novel survival-associated biomarkers in oral rinse samples collected from patients with oral squamous cell carcinoma (OSCC).

MATERIALS AND METHODS

We screened for putative survival-associated markers using publicly available methylation array data from 88 OSCC tumors. Cox models were then fit to methylation array data restricted to these putative loci in oral rinse samples of 82 OSCC patients from greater Boston. Pyrosequencing assays were designed for each locus that replicated in the oral rinse samples and applied to a validation set of oral rinse samples from another 61 OSCC patients.

RESULTS

We identified 7 survival-associated methylation markers in oral rinse samples from OSCC patients, and have validated one, located in the body of GABBR1, by pyrosequencing.

CONCLUSION

The 7 CpG loci identified through this study represent novel prognostic biomarkers for patients with OSCC that can be detected using a non-invasive oral rinse collection technique.

Let-7 microRNA-binding-site polymorphism in the 3'UTR of KRAS and colorectal cancer outcome: a systematic review and meta-analysis

There is a small but growing body of literature regarding the predictive utility of a Let-7 microRNA-binding-site polymorphism in the 3′-untranslated region (UTR) of KRAS (KRAS-LCS6) for colorectal cancer outcome, although the results are conflicting. We performed a review and meta-analysis in an attempt to better clarify this relationship. A PubMed search was conducted to identify all studies reporting on KRAS let-7 microRNA-binding site polymorphism (LCS6; rs61764370) and colorectal cancer outcome. Hazard ratios (HR) and corresponding 95% confidence intervals (CI) were extracted or estimated from each manuscript. Log HRs and log CIs were combined across studies using the inverse-variance weight to calculate fixed- and random-effects summary estimates and corresponding 95% CIs for overall and progression-free survival. We did not observe any significant association between overall or progression-free survival, neither when considering all colorectal cancer patients nor for subgroup analyses (metastatic, anti-EGFR [epidermal growth factor receptor] treatment, or KRAS wild type). There was substantial heterogeneity across studies, overall and among subgroups analyzed. We have found no clear evidence to support an association between the KRAS-LCS6 genotype and overall or progression-free survival among colorectal cancer patients, even after conducting subgroup analyses by stage and anti-EGFR treatment status. This information helps to clarify the confusing body of literature regarding the clinical implications of the KRAS-LCS6 genetic variant on colorectal cancer outcomes, indicating that it should not be used at the present time to personalize therapeutic strategies (PROSPERO registration number: CRD42013005325).

Leukocyte-adjusted epigenome-wide association studies of blood from solid tumor patients

Epigenome-wide studies of DNA methylation using blood-derived DNA from cancer patients are complicated by the heterogeneity of cell types within blood and the associated cell lineage specification of DNA methylation signatures. Here, we applied a novel set of analytic approaches to assess the association between cancer case-status and DNA methylation adjusted for leukocyte variation using blood specimens from three case-control cancer studies (bladder: 223 cases, 205 controls; head and neck: 92 cases, 92 controls; and ovarian: 131 cases, 274 controls). Using previously published data on leukocyte-specific CpG loci and a recently described approach to deconvolute subject-specific blood composition, we performed an epigenome-wide analysis to examine the association between blood-based DNA methylation patterns and each of the three aforementioned solid tumor types adjusted for cellular heterogeneity in blood. After adjusting for leukocyte profile in our epigenome-wide analysis, the omnibus association between case-status and methylation was significant for all three studies (bladder cancer: P = 0.047; HNSCC: P = 0.013; ovarian cancer: P = 0.0002). Subsequent analyses revealed that CpG sites associated with cancer were enriched for transcription factor binding motifs involved with cancer-associated pathways. These results support the existence of cancer-associated DNA methylation profiles in the blood of solid tumor patients that are independent of alterations in normal leukocyte distributions. Adoption of the methods developed here will make it feasible to rigorously assess the influence of variability of normal leukocyte profiles when investigating cancer related changes in blood-based epigenome-wide association studies.

High-risk HPV types and head and neck cancer

Although HPV16 has been strongly implicated in oropharyngeal carcinogenesis, the role of other high-risk HPV types in the etiology of head and neck cancer remains unclear. To date, few data exist addressing the nature of the association between antibodies to oncogenic proteins of non-HPV16 HPVs in relation to head and neck cancer. We examined the relationship between multiple HPV types (HPV6, 11, 16, 18, 31, 33, 45, 52, 58) and head and neck squamous cell carcinoma (HNSCC) in a large population-based case-control study (1069 cases and 1107 controls). Serological measures for HPV types included antibodies to L1, E6 and/or E7. In a secondary analysis, we excluded HPV16 seropositive subjects to examine independent associations with other high-risk HPVs. All analyses were adjusted for age, race, sex, education, smoking and alcohol consumption. Statistically significant associations were observed for HPV16, 18, 33 and 52 and risk of HNSCC after mutually adjusting for HPV types. Among HPV16 seronegative subjects, elevated risks of HNSCC were observed for HPV18 E6 (OR = 4.19, 95% CI = 1.26-14.0), HPV33 E6 (OR = 7.96, 95% CI = 1.56-40.5) and HPV52 E7 (OR = 3.40, 95% CI = 1.16-9.99). When examined by tumor type, associations with HPV18 and HPV33 remained statistically significant for oropharyngeal cancer, and HPV52 was associated with oral cancer. In addition, magnitude of associations for HNSCC increased markedly with increasing number of seropositive high-risk HPV infections. High-risk HPV types, other than HPV16, are likely to be involved in the etiology of HNSCC.

Occupational dust exposure and head and neck squamous cell carcinoma risk in a population-based case-control study conducted in the greater Boston area

Head and neck cancers account for an estimated 549,000 global cancer diagnoses each year. While tobacco use, alcohol consumption, and HPV16 infection are considered to be the major risk factors for this disease, occupational risk factors, including exposure to asbestos, have also been described, although dust exposures other than asbestos have been historically understudied. We have investigated the relationship between occupational exposures to five types of dusts, including sawdust, concrete dust, leather dust, metal dust, and chimney soot, and head and neck squamous cell carcinomas (HNSCC) in the greater Boston area. We report findings from a population-based case–control study involving 951 incident HNSCC cases and 1193 controls, frequency matched on age (±3 years), sex, and town/neighborhood of residence. Multivariable logistic regression was used to assess the association between occupational exposure to each type of dust and HNSCC, overall and by primary tumor site. After adjusting for age, sex, race, smoking, alcohol consumption, education, and HPV16 serology, laryngeal carcinoma risk increased for each decade of occupational exposure to sawdust (OR = 1.2, 95% CI: 1.0, 1.3) and metal dust (OR = 1.2, 95% CI: 1.0, 1.4); and HNSCC risk increased for each decade of occupational leather dust exposure (OR = 1.5, 95% CI: 1.2, 1.9). We have provided evidence for an association between occupational sawdust and metal dust and laryngeal squamous cell carcinoma, and leather dust and HNSCC, with increasing risk with longer duration at the exposed occupation.

Occupational asbestos exposure is associated with pharyngeal squamous cell carcinoma in men from the greater Boston area

OBJECTIVES

Asbestos is the name given to a group of naturally occurring silicate mineral fibres that were widely used in industry during the 20th century due to their desirable physical properties. Although use in the USA has fallen over the last three decades, significant exposure in the developing world continues and the burden of disease is considerable. Asbestos is a known risk factor for several malignant diseases, including lung cancer and mesothelioma, and has more recently been implicated in pharyngeal and laryngeal cancer. However, studies of asbestos and cancers of the larynx or pharynx with adequate sample size that control for major head and neck squamous cell carcinoma (HNSCC) risk factors remain relatively sparse.

METHODS

We report findings from a case-control study of 674 incident male HNSCC cases from the greater Boston region and 857 population-based male controls, matched on age (±3 years), sex, and town or neighbourhood of residence. Multivariable logistic regression was used to assess the association between occupational asbestos exposure and HNSCC by primary tumour site.

RESULTS

190 cases (28.2%) and 203 controls (23.7%) reported occupational exposure to asbestos. Occupational asbestos exposure was associated with elevated risk of pharyngeal carcinoma in men (OR 1.41, 95% CI 1.01 to 1.97), adjusted for age, race, smoking, alcohol consumption, education, income and HPV16 serology, with borderline increasing risk for each decade in the exposed occupation (OR 1.10, 95% CI 0.99 to 1.23).

CONCLUSIONS

These observations are consistent with mounting evidence that asbestos is a risk factor for pharyngeal cancer.

The fate is not always written in the genes: epigenomics in epidemiologic studies

Cost-effective, high-throughput epigenomic technologies have begun to emerge, rapidly replacing the candidate gene approach to molecular epidemiology and offering a comprehensive strategy for the study of epigenetics in human subjects. Epigenome-wide association studies (EWAS) provide new opportunities for advancing our understanding of epigenetic changes associated with complex disease states. However, such analyses are complicated by the dynamic nature of DNA methylation. In contrast to genomic studies, where genotype is essentially constant across somatic cells, EWAS present a new set of challenges, largely due to differential DNA methylation across distinct cell types, particularly for studies involving heterogeneous tissue sources, and changes in the epigenetic profile that occur over time. This review describes potential applications of EWAS from the viewpoint of the molecular epidemiologist, along with special considerations and pitfalls involved in the design of such studies.

Blood-based profiles of DNA methylation predict the underlying distribution of cell types: a validation analysis

The potential influence of underlying differences in relative leukocyte distributions in studies involving blood-based profiling of DNA methylation is well recognized and has prompted development of a set of statistical methods for inferring changes in the distribution of white blood cells using DNA methylation signatures. However, the extent to which this methodology can accurately predict cell-type proportions based on blood-derived DNA methylation data in a large-scale epigenome-wide association study (EWAS) has yet to be examined. We used publicly available data deposited in the Gene Expression Omnibus (GEO) database (accession number GSE37008), which consisted of both blood-derived epigenome-wide DNA methylation data assayed using the Illumina Infinium HumanMethylation27 BeadArray and complete blood cell (CBC) counts among a community cohort of 94 non-diseased individuals. Constrained projection (CP) was used to obtain predictions of the proportions of lymphocytes, monocytes and granulocytes for each of the study samples based on their DNA methylation signatures. Our findings demonstrated high consistency between the average CBC-derived and predicted percentage of monocytes and lymphocytes (17.9% and 17.6% for monocytes and 82.1% and 81.4% for lymphocytes), with root mean squared error (rMSE) of 5% and 6%, for monocytes and lymphocytes, respectively. Similarly, there was moderate-high correlation between the CP-predicted and CBC-derived percentages of monocytes and lymphocytes (0.60 and 0.61, respectively), and these results were robust to the number of leukocyte differentially methylated regions (L-DMRs) used for CP prediction. These results serve as further validation of the CP approach and highlight the promise of this technique for EWAS where DNA methylation is profiled using whole-blood genomic DNA.

Gastric reflux is an independent risk factor for laryngopharyngeal carcinoma

BACKGROUND

Gastric reflux can reach into the upper airway, inducing cellular damage in the epithelial lining. This condition is believed to be a risk factor for development of laryngopharyngeal squamous cell carcinoma (LPSCC), although the literature is conflicting.

METHODS

To better clarify this relationship, we assessed the association of self-reported heartburn history and medication use among 631 patients with LPSCCs and 1234 control subjects (frequency-matched on age, gender, and town of residence) enrolled as part of a population-based case-control study of head and neck squamous cell carcinoma in the greater Boston area.

RESULTS

After adjusting for age, gender, race, smoking, alcohol consumption, HPV16 seropositivity, education, and body mass index, subjects reporting a history of frequent heartburn and who were neither a heavy smoker nor heavy drinker had a significantly elevated risk of LPSCCs [OR, 1.78; 95% confidence interval (CI), 1.00-3.16]. Among those with a history of heartburn, there was an inverse association between antacid use and LPSCCs relative to those never taking heartburn medication (OR, 0.59; 95% CI, 0.38-0.93) that remained consistent when analyzed by smoking/drinking status, HPV16 status, or by primary tumor site.

CONCLUSIONS

Our data show that gastric reflux is an independent risk factor for squamous cancers of the pharynx and larynx. Further studies are needed to clarify the possible chemopreventive role of antacid use for patients with gastric reflux.

IMPACT

Elucidation of additional risk factors for head and neck cancer can allow for risk stratification and inform surveillance of high-risk patients.

Abstract 3627: Occupational asbestos exposure is associated with head and neck cancer

Asbestos describes a group of naturally occurring silicate mineral fibers that were frequently used in industry during the 20th century due to their desirable flame retardant and tensile properties. Although use has fallen over the last three decades, exposure continues and the burden of disease is considerable. The primary routes of exposure to the fibers include inhalation and ingestion. Asbestos is a known risk factor for several malignant respiratory diseases, including lung cancer and mesothelioma, and has more recently been implicated in pharyngeal and laryngeal cancer. However, studies of asbestos and cancers of the larynx or pharynx with adequate sample-size and control for other risk factors for head and neck squamous cell carcinoma (HNSCC) such as smoking and drinking habit remain somewhat sparse. We report findings from a case-control study consisting of 934 incident HNSCC cases from the greater Boston region and 1180 population-based controls, frequency matched on age (+/- 3 years), sex, and town or neighborhood of residence. Study subjects completed a self-administered questionnaire that provided detailed data on history of asbestos exposure, sociodemographics and personal characteristics, alcohol and tobacco use, personal and family cancer history, and other relevant dietary, occupational, residential and medical exposures. Occupational asbestos exposure was dichotomized as exposed or never exposed based on self reported occupation data. Multivariate unconditional logistic regression was used to assess the association between asbestos exposure and HNSCC, overall and by primary tumor site and smoking history. A total of 217 cases (23.2%) and 226 controls (19.2%) reported an occupational exposure to asbestos. We observed a borderline association of asbestos exposure and laryngopharyngeal cancer (OR = 1.23, 95% CI: 0.95-1.59), adjusted for age, sex, race, smoking, alcohol consumption, and education. After stratifying by smoking history, a significant association was observed between asbestos exposure and laryngopharyngeal cancer among ever-smokers (OR = 1.36, 95% CI: 1.00-1.84). These observations are consistent with the mounting evidence that asbestos is a risk factor for pharyngeal and laryngeal cancer.

Citation Format: Scott M. Langevin, Mattie H. O'Sullivan, Jennifer L. Valerio, Kate M. Applebaum, Melissa Eliot, Michael D. McClean, Karl T. Kelsey. Occupational asbestos exposure is associated with head and neck cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3627. doi:10.1158/1538-7445.AM2013-3627

Smokeless tobacco and risk of head and neck cancer: evidence from a case-control study in New England

Current studies suggesting that smokeless tobacco use increases the risk of head and neck cancer are hampered by small numbers. Consequently, there remains uncertainty in the magnitude and significance of this risk. We examined the relationship between smokeless tobacco use and head and neck squamous cell carcinoma (HNSCC) in a population-based case-control study with 1,046 cases and 1,239 frequency-matched controls. Logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (95% CI), adjusting for age, gender, race, education level, cigarette smoking, and alcohol consumption. A nonsignificant elevated association between having ever used smokeless tobacco and HNSCC risk (OR = 1.20, 95% CI: 0.67-2.16) was observed. Individuals who reported 10 or more years of smokeless tobacco use had a significantly elevated risk of HNSCC (OR = 4.06, 95% CI: 1.31-12.64), compared to never users. In an analysis restricted to never cigarette smokers, a statistically significant association was observed between ever use of smokeless tobacco and the risk of HNSCC (OR = 4.21, 95% CI: 1.01-17.57). These findings suggest that long-term use of smokeless tobacco increases the risk of HNSCC.

Abstract 4240: A novel approach to adjust for immune cell distribution in blood-based epigenome-wide association studies of cancer

Epigenome-wide association studies (EWAS) promise to advance our understanding of epigenetic variation in cancer and are made possible by the recent emergence of cost-effective high-throughput technologies. Blood is the most widely available source of genomic DNA that can be used for study of cancer-associated alterations in DNA methylation (DNAm). These analyses are complicated by the heterogeneity of blood, which represents multiple cell types with unique DNAm signatures. Shifts in immune profile could confound results since altered leukocyte numbers are common in response to exposures or disease. We applied a novel approach to blood-based EWAS, adjusting for leukocyte composition estimated by epigenetic deconvolution of blood. Normal human peripheral blood leukocytes (n = 47) were isolated by magnetic activated cell sorting and purity was confirmed by fluorescence activated cell sorting. DNAm was interrogated using the Infinium HumanMethylation27 BeadArray (Illumina) on the sorted leukocyte samples and peripheral blood samples from 3 independent case-control studies of bladder cancer (223 cases, 205 controls), head and neck squamous cell carcinoma (HNSCC; 92 cases, 92 controls), and ovarian cancer (131 cases, 274 controls). Differentially methylated loci associated with leukocyte lineage were identified using a series of linear mixed effects models fit to the DNAm data for each of the 26,486 autosomal CpGs for the sorted leukocytes, yielding an F-statistic for each locus. The subject-specific leukocyte distribution (vector ω) was estimated using constrained projections, as previously described by Houseman et al (2012). Several regression parameters were estimated: βj, representing the association of case-status and DNAm at CpG j, unadjusted for ω; αj, representing the corresponding association adjusted for ω, and Γ, the association of case-status and ω. Γ, β and α were each adjusted for age, sex and smoking for bladder cancer and HNSCC, and age for ovarian cancer. Statistical inference was achieved by permutation, where null distributions were obtained by permuting case-status with respect to DNAm values and other covariates, using an omnibus test adjusted for multiple-comparisons, constructed by comparing the observed average F-statistic across all CpGs to the corresponding quantity obtained from the permutation distribution. After adjusting for leukocyte composition (α), the association between DNAm and case-status was significant for all 3 studies (bladder cancer: p = 0.047; HNSCC: p = 0.013; ovarian cancer: p = 0.0002). Subsequent analyses revealed that cancer-associated pathways were overrepresented among significant loci. These results indicate cancer-specific variation in DNAm of peripheral blood, independent of immune cell shifts. Further research is indicated for elucidation of mechanisms driving these observations.

Citation Format: Scott M. Langevin, E. A. Houseman, William P. Accomando, Devin C. Koestler, Brock C. Christensen, Heather H. Nelson, Margaret R. Karagas, Carmen J. Marsit, John K. Wiencke, Karl T. Kelsey. A novel approach to adjust for immune cell distribution in blood-based epigenome-wide association studies of cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4240. doi:10.1158/1538-7445.AM2013-4240

Periodontal disease and mouthwash use are risk factors for head and neck squamous cell carcinoma

PURPOSE

The purpose of this study was to examine associations between oral hygiene, including history of periodontal disease and mouthwash use, and risk of head and neck squamous cell carcinoma (HNSCC).

METHODS

We measured history of oral hygiene and dental care on 513 HNSCC cases and 567 controls from a population-based study of HNSCC. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CI).

RESULTS

Periodontal disease was associated with a slightly elevated risk of HNSCC (OR = 1.09, 95% CI: 1.02, 1.16). Using any type of mouthwash at least once per day was associated with increased risk compared to never using mouthwash (OR = 1.11, 95% CI: 1.02, 1.20). HNSCC was associated with frequent use of non-alcoholic mouthwash compared to using any kind of mouthwash rarely or never (OR = 1.24, 95% CI: 1.05, 1.47).

CONCLUSIONS

Our results support an association between periodontal disease and HNSCC. Our data suggest that mouthwash use is associated with HNSCC, but we noted no difference between the effects of alcohol-containing and non-alcoholic mouthwashes.

Regular dental visits are associated with earlier stage at diagnosis for oral and pharyngeal cancer

PURPOSE

Oral and pharyngeal cancer patients diagnosed at an advanced stage experience increased morbidity and mortality relative to those with localized disease. The aim of this study was to assess the impact of dental insurance status and regularity of dental visits on early detection of oral and pharyngeal cancer.

METHODS

We examined the relationship of dental insurance and frequency of dental visits with stage at diagnosis among 441 oral and pharyngeal cancer cases from a population-based study of head and neck cancer. Ordinal logistic regression models were used to assess the association with stage, and tumor (T) and nodal (N) classification.

RESULTS

Never or rarely going to the dentist was associated with being diagnosed at higher stage for oral and pharyngeal cancer (cumulative OR = 2.28, 95 % CI: 1.02-5.10) and oral cancer (cumulative OR = 9.17, 95 % CI: 2.70-31.15) compared to those going to the dentist at least annually. Oral and pharyngeal cancer patients who went to the dentist infrequently (cumulative OR = 1.82, 95 % CI: 1.09-3.05) or rarely/never (cumulative OR = 3.24, 95 % CI: 1.59-6.57) were diagnosed with a higher T classification compared with those who went at least annually.

CONCLUSIONS

Receipt of regular dental examinations at least annually may reduce the public health burden of oral and pharyngeal cancer by facilitating earlier detection of the disease.

Peripheral blood immune cell methylation profiles are associated with nonhematopoietic cancers

BACKGROUND

Blood leukocytes from patients with solid tumors exhibit complex and distinct cancer-associated patterns of DNA methylation. However, the biologic mechanisms underlying these patterns remain poorly understood. Because epigenetic biomarkers offer significant clinical potential for cancer detection, we sought to address a mechanistic gap in recently published works, hypothesizing that blood-based epigenetic variation may be due to shifts in leukocyte populations.

METHODS

We identified differentially methylated regions (DMR) among leukocyte subtypes using epigenome-wide DNA methylation profiling of purified peripheral blood leukocyte subtypes from healthy donors. These leukocyte-tagging DMRs were then evaluated using epigenome-wide blood methylation data from three independent case-control studies of different cancers.

RESULTS

A substantial proportion of the top 50 leukocyte DMRs were significantly differentially methylated among head and neck squamous cell carcinoma (HNSCC) cases and ovarian cancer cases compared with cancer-free controls (48 and 47 of 50, respectively). Methylation classes derived from leukocyte DMRs were significantly associated cancer case status (P < 0.001, P < 0.03, and P < 0.001) for all three cancer types: HNSCC, bladder cancer, and ovarian cancer, respectively and predicted cancer status with a high degree of accuracy (area under the curve [AUC] = 0.82, 0.83, and 0.67).

CONCLUSIONS

These results suggest that shifts in leukocyte subpopulations may account for a considerable proportion of variability in peripheral blood DNA methylation patterns of solid tumors.

IMPACT

This illustrates the potential use of DNA methylation profiles for identifying shifts in leukocyte populations representative of disease, and that such profiles may represent powerful new diagnostic tools, applicable to a range of solid tumors.

Peripheral blood DNA methylation profiles are indicative of head and neck squamous cell carcinoma: an epigenome-wide association study

Head and neck cancer accounts for an estimated 47,560 new cases and 11,480 deaths annually in the United States, the majority of which are squamous cell carcinomas (HNSCC). The overall 5 year survival is approximately 60% and declines with increasing stage at diagnosis, indicating a need for non-invasive tests that facilitate the detection of early disease. DNA methylation is a stable epigenetic modification that is amenable to measurement and readily available in peripheral blood. We used a semi-supervised recursively partitioned mixture model (SS-RPMM) approach to identify novel blood DNA methylation markers of HNSCC using genome-wide methylation array data for peripheral blood samples from 92 HNSCC cases and 92 cancer-free control subjects. To assess the performance of the resultant markers, we constructed receiver operating characteristic (ROC) curves and calculated the corresponding area under the curve (AUC). Cases and controls were best differentiated by a methylation profile of six CpG loci (associated with FGD4, SERPINF1, WDR39, IL27, HYAL2 and PLEKHA6), with an AUC of 0.73 (95% CI: 0.62-0.82). After adjustment for subject age, gender, smoking, alcohol consumption and HPV16 serostatus, the AUC increased to 0.85 (95% CI: 0.76-0.92). We have identified a novel blood-based methylation profile that is indicative of HNSCC with a high degree of accuracy. This profile demonstrates the potential of DNA methylation measured in blood for development of non-invasive applications for detection of head and neck cancer.

Allergies and risk of head and neck cancer

BACKGROUND

Individuals with allergies have a heightened Th2 (T helper 2) immunity, which may provide advantages in controlling tumor growth. Inverse associations have been reported among individuals with allergies and risk of brain and pancreatic cancers.

METHODS

We examined the relationship between allergies and risk of head and neck squamous cell carcinoma (HNSCC) in a population-based case-control study with 1,014 cases and 1,193 frequency-matched controls. Logistic regression models were used to estimate odds ratios (OR) and 95 % confidence intervals (95 % CI) controlling for age, sex, race, smoking history, alcohol consumption, and education. In addition, in a subset of the population, models were adjusted for HPV16 status.

RESULTS

Individuals with allergies had a 19 % lower risk of HNSCC (OR = 0.81, 95 % CI = 0.67-0.98). Associations with allergies were stronger for laryngeal (OR = 0.66, 95 % CI = 0.45-0.97) and oropharyngeal (OR = 0.73, 95 % CI = 0.57-0.92) cancers, while no association was observed for oral cavity cancers (OR = 0.98, 95 % CI = 0.76-1.26). History of asthma was not associated with overall HNSCC, but the association was statistically significant for oropharyngeal cancer (OR = 0.67, 95 % CI = 0.44-0.99). HPV16 status did not confound or modify the associations with allergies.

CONCLUSIONS

Elevated Th2 immunity in individuals with history of allergies and asthma may reduce the risk of HNSCC. Additional research into related mechanisms may provide new insights into how to treat HNSCC.

IMPACT

These findings may provide new insight into biological pathways that could lead to a better understanding of the etiology of this disease.

Abstract 5022: Immune biology drives cancer specific methylation profiles in blood

Blood leukocytes from patients with solid tumors exhibit complex and distinct cancer-associated patterns of DNA methylation. However, the biological mechanisms underlying these patterns remain poorly understood. Since epigenetic biomarkers offer significant clinical potential for cancer detection, we sought to address a mechanistic gap in recently published works, hypothesizing that this variation is in large part due to shifts in leukocyte populations. To discern differentially methylated regions (DMRs) among leukocyte subtypes, we assessed epigenome-wide DNA methylation in sorted, purified, healthy human peripheral blood leukocyte subtypes. Performing a targeted analysis of leukocyte DMRs from epigenome-wide blood methylation data in three independent case-control studies of different cancers revealed that leukocyte DMRs predict case status with a high degree of accuracy (area under the curve = 0.82, 0.83, and 0.67, forhead and neck squamous cell carcinoma (HNSCC), ovarian, and bladder cancer, respectively). These results demonstrate that blood-derived differences in DNA methylation patterns in patients with solid tumors are largely attributable to systematic differences in the DMRs that define specific, known leukocyte sub-populations, suggesting that the unique epigenetic signatures in blood from solid tumor patients arise as a result of immune responses represented by shifts in leukocyte populations.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5022. doi:1538-7445.AM2012-5022

In utero exposures, infant growth, and DNA methylation of repetitive elements and developmentally related genes in human placenta

BACKGROUND

Fetal programming describes the theory linking environmental conditions during embryonic and fetal development with risk of diseases later in life. Environmental insults in utero may lead to changes in epigenetic mechanisms potentially affecting fetal development.

OBJECTIVES

We examined associations between in utero exposures, infant growth, and methylation of repetitive elements and gene-associated DNA in human term placenta tissue samples.

METHODS

Placental tissues and associated demographic and clinical data were obtained from subjects delivering at Women and Infants Hospital in Providence, Rhode Island (USA). Methylation levels of long interspersed nuclear element-1 (LINE-1) and the Alu element AluYb8 were determined in 380 placental samples from term deliveries using bisulfite pyrosequencing. Genomewide DNA methylation profiles were obtained in a subset of 184 samples using the Illumina Infinium HumanMethylation27 BeadArray. Multiple linear regression, model-based clustering methods, and gene set enrichment analysis examined the association between birth weight percentile, demographic variables, and repetitive element methylation and gene-associated CpG locus methylation.

RESULTS

LINE-1 and AluYb8 methylation levels were found to be significantly positively associated with birth weight percentile (p = 0.01 and p < 0.0001, respectively) and were found to differ significantly among infants exposed to tobacco smoke and alcohol. Increased placental AluYb8 methylation was positively associated with average methylation among CpG loci found in polycomb group target genes; developmentally related transcription factor binding sites were overrepresented for differentially methylated loci associated with both elements.

CONCLUSIONS

Our results suggest that repetitive element methylation markers, most notably AluYb8 methylation, may be susceptible to epigenetic alterations resulting from the intrauterine environment and play a critical role in mediating placenta function, and may ultimately inform on the developmental basis of health and disease.

Abstract A37: Peripheral blood DNA methylation profiles are predictive of head and neck squamous cell carcinoma

Head and neck cancer accounts for an estimated 47,560 new cases and 11,480 deaths annually in the United States, the majority of which are squamous cell carcinomas (HNSCC). The overall 5-year survival is approximately 60% and declines with increasing stage at diagnosis, indicating a need for non-invasive tests that facilitate the detection of early disease. DNA methylation is a stable epigenetic modification that is amenable to measurement and readily available in peripheral blood. DNA methylation profiles are commonly altered in tumor tissue, including HNSCC. We applied a semi-supervised recursively partitioned mixture model (SS-RPMM) approach to identify novel blood DNA methylation markers of HNSCC using genome-wide methylation array data (26,486 autosomal CpG loci) for peripheral blood samples from 92 HNSCC cases and 92 cancer-free controls. Subjects were randomly split into training (n = 92) and testing (n = 92) sets, stratified by case-control status to ensure an equal distribution of cases and controls between sets. A series of mixed effects models were fit to the training data only and CpG loci were ranked according to absolute t-statistic. The top M loci were selected to train a classifier, where M was chosen using a nested cross-validation procedure, which was then fit to the testing data. To assess the performance of the resultant markers in the testing data, we constructed receiver operating characteristic (ROC) curves and calculated the corresponding area under the curve (AUC). Cases and controls were best differentiated by a methylation profile of 6 CpG loci (associated with FGD4, SERPINF1, WDR39, IL27, HYAL2 and PLEKHA6), resulting in 4 classes, with an AUC of 0.73 (95% CI: 0.62–0.82). After adjustment for subject age, gender, smoking, alcohol consumption and HPV16 serostatus, the AUC increased to 0.85 (95% CI: 0.76–0.92). There was no significant difference in stage at diagnosis, tumor site or HPV-16 serostatus for cases by class. We have identified a novel blood-based methylation profile that is predictive of HNSCC with a high degree of accuracy. Although not yet adequate for use in clinical settings, this profile demonstrates the potential of DNA methylation measured in blood for development of non-invasive applications for detection of head and neck cancer.

Citation Information: Cancer Prev Res 2011;4(10 Suppl):A37.

Female hormonal and reproductive factors and head and neck squamous cell carcinoma risk

Men are much more likely than women to develop head and neck squamous cell carcinoma (HNSCC), a discrepancy that is insufficiently explained by gender differences in smoking and alcohol consumption. It has been hypothesized that differential hormonal exposures may account for some of this risk but thus far the literature on female reproductive factors and HNSCC risk has been sparse. To address the association of HNSCC with female hormonal and reproductive factors, a case-control study was conducted on 149 women with head and neck cancer and 158 controls. After adjusting for potential confounding, postmenopausal women using female hormones for more than 5 years showed a borderline protective effect for HNSCC (adjusted OR = 0.47, 95% CI: 0.20-1.08), with a borderline trend across duration of use categories (P = 0.06). There was no association of HNSCC with age at menarche, hysterectomy/oophorectomy status, oral contraceptive use, history of fertility medication, or number of pregnancies, parity, or age at first pregnancy or live birth. The findings of this study do not support a link between HNSCC and reproductive factors, although the borderline association with HRT warrants further investigation.

The influence of aging, environmental exposures and local sequence features on the variation of DNA methylation in blood

In order to properly comprehend the epigenetic dysregulation that occurs during the course of disease, there is a need to characterize the epigenetic variability in healthy individuals that arises in response to aging and exposures, and to understand such variation within the biological context of the DNA sequence. We analyzed the methylation of 26,486 autosomal CpG loci in blood from 205 healthy subjects, using three complementary approaches to assess the association between methylation, age or exposures, and local sequence features, such as CpG island status, repeat sequences, location within a polycomb target gene or proximity to a transcription factor binding site. We clustered CpGs (1) using unsupervised recursively partitioned mixture modeling (RPMM) and (2) bioinformatically-informed methods, and (3) also employed a marginal model-based (non-clustering) approach. We observed associations between age and methylation and hair dye use and methylation, where the direction and magnitude was contingent on the local sequence features of the CpGs. Our results demonstrate that CpGs are differentially methylated dependent upon the genomic features of the sequence in which they are embedded, and that CpG methylation is associated with age and hair dye use in a CpG context-dependent manner in healthy individuals.

MicroRNA-137 promoter methylation is associated with poorer overall survival in patients with squamous cell carcinoma of the head and neck

BACKGROUND

The overall 5-year survival rate of approximately 60% for head and neck cancer patients has remained essentially unchanged over the past 30 years. MicroRNA-137 (miR-137) plays an essential role in cell-cycle control at the G1/S-phase checkpoint. However, the aberrant miR-137 promoter methylation observed in squamous cell carcinoma of the head and neck (SCCHN) suggests a tumor-specific molecular defect that may contribute to disease progression.

METHODS

The goal of this study was to assess, in formalin-fixed, paraffin-embedded tumor tissue, the association between miR-137 promoter methylation and survival (both overall and disease free) and with prognostic factors including stage, tumor size, lymph node positivity, tumor grade, and surgical tumor margin positivity.

RESULTS

The promoter methylation status of miR-137 was ascertained by methylation-specific polymerase chain reaction and detected in 11 of 67 SCCHN patients (16.4%), with no significant differences according to site (oral cavity, pharynx, larynx). Methylation of the miR-137 promoter was significantly associated with overall survival (hazard ratio, 3.68; 95% confidence interval, 1.01-13.38) but not with disease-free survival or any of the prognostic factors evaluated.

CONCLUSIONS

The results of this study indicate that miR-137 is methylated in tumor tissue from pharyngeal and laryngeal squamous cancers, in addition to oral squamous cell carcinoma, and that miR-137 promoter methylation has potential utility as a prognostic marker for SCCHN.

Determinants of head and neck cancer survival by race

BACKGROUND

Several factors contribute to the documented racial disparity in head and neck cancer, among which are socioeconomic status, access to care, and biologic factors.

METHODS

Clinical characteristics of 87 African-American patients with head and neck cancer and a random sample of 261 white patients matched on age and smoking dose were associated with outcome.

RESULTS

Black patients with cancers of the oral cavity and larynx were more likely diagnosed with advanced stages than whites, after adjusting for socioeconomic and insurance status and other confounding factors. There was a significant difference in relapse-free survival between blacks and whites with tumors of the larynx (hazard ratio [HR] = 3.36, 95% confidence interval [CI]: 1.62-7.00), but not with tumors of the oral cavity or pharynx.

CONCLUSIONS

Differences in disease outcome may be attributed to a combination of tumor stage, socioeconomic status, and access to health care. The inclusion of biologic markers such as human papillomavirus (HPV) status is needed in future studies to further evaluate racial disparities in head and neck cancer outcomes.

The impact of health insurance status on the survival of patients with head and neck cancer

BACKGROUND

In 2006, it was estimated that 47 million people in the United States are without insurance. Studies have shown that patients who are uninsured or are insured by Medicaid are more likely to present with more advanced cancer. The objective of this study was to examine whether cancer recurrence and mortality of patients diagnosed with squamous cell carcinoma of the head and neck are associated with insurance status, after adjusting for known cancer risk factors. The main outcome measures were overall survival and relapse-free survival.

METHODS

Retrospective cohort of patients with a biopsy-proven primary squamous cell carcinoma of the oral cavity, pharynx, or larynx diagnosed or treated at the University of Pittsburgh Medical Center between 1998 and 2007. Patients were stratified by their insurance status, including private insurance, uninsured/Medicaid, Medicare disability (Medicare under age 65), and Medicare 65 years + . Covariates included age, gender, race, smoking status, alcohol consumption, anatomic tumor site, treatment, stage at diagnosis, and occupational prestige score. Cox proportional hazards regression was used to estimate the effect of insurance status on overall survival, relapse-free survival, tumor stage, and lymph node involvement.

RESULTS

A total of 1231 patients were included in the analysis. Patients with Medicaid/uninsured (hazard ratio [HR], 1.50; 95% confidence interval [CI], 1.07-2.11) and Medicare disability (HR, 1.69; 95% CI, 1.16-2.48) had significantly lower overall survival compared with patients with private insurance; the result was independent of variables known to affect outcome, such as alcohol and tobacco use. For all squamous cell carcinoma of the head and neck (SCCHN) cancer sites, Medicaid and uninsured patients were significantly more likely to present with an advanced stage tumor at diagnosis (odds ratio [OR] = 2.94; 95% CI, 1.72-5.01) and to present with at least 1 positive lymph node (OR = 1.84; 95% CI, 1.16-2.90) compared with patients with private insurance.

CONCLUSIONS

Patients with Medicaid/uninsured and Medicare disability were at increased risk of death after a diagnosis of SCCHN when compared with patients with private insurance, after adjustment for age, gender, race, smoking, alcohol use, site, socioeconomic status, treatment, and cancer stage.