Elena-Sophie Prigge

Prognostic Impact of AJCC/UICC 8th Edition New Staging Rules in Oropharyngeal Squamous Cell Carcinoma

Introduction The purpose of this study was to test whether the 8th edition of the AJCC/UICC TNM staging system (UICC) precisely differentiates between stages and reflects disease outcome in human papilloma virus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC). Patients and methods OPSCC patients that were diagnosed between 2000 and 2016 were included in this analysis and HPV status was determined by combined DNA and p16 testing. Stratification was done according to 7th and 8th UICC staging rules. Incidence trends of HPV-associated tumorigenesis, 5-year overall survival (OS) according to tumor stages as well as the influence of therapy and prognostic factors toward the outcome were calculated using Kaplan–Meier method and Cox proportional-hazards model. Results A significant increase [2000; n = 8/39 (21%)–2015; n = 17/32 (53%); p = 0.002] in HPV-associated OPSCC was seen in the observation period. Together, 150/599 (25.0%) of the patients had HPV-driven OPSCC and 64.7% of curative treatments in all OPSCC patients included upfront surgery of the primary and the neck. 7th edition staging rules led to no discrimination in all respective four UICC stages in HPV OPSCC underlining the need for new staging rules. However, only discrimination between stages I vs. II and III vs. IV was significant in our patients with HPV-OPSCC (94.4 vs. 77.5%; p = 0.031 and 63.9 vs. 25.0%; p = 0.013), and stages II vs. III did not differ in OS rates (p = 0.257), when applying the new staging rules. For HPV-negative OPSCC, significant outcome differences were only seen between UICC stages III vs. IV (57.6 vs. 35.2%; p = 0.012). Discussion While the 7th edition of UICC shows invalid discrimination between stages, the 8th edition is more suitable for HPV-associated carcinoma. Due to lack of differentiation between stages II and III further adaption is essential.

Risk Factors for Overall Survival Outcome in Surgically Treated Human Papillomavirus-Negative and Positive Patients with Oropharyngeal Cancer

Analysis of overall survival by number of radium-223 injections received in an international expanded access program (iEAP)Introduction: This study reports the oncological outcome of a non-selected series of patients with human papillomavirus(HPV)-positive and -negative oropharyngeal squamous cell carcinoma (OSCC) preferentially managed with upfront surgery. Methods: Consecutive OSCC cases (n = 378) diagnosed from 2000 to 2010 in our department were evaluated for risk factors, HPV association, therapy and overall survival (OS). HPV status was determined by combined DNA and p16 testing, and treatment was defined as the first course of treatment with any kind of surgery (upfront surgery) or primary chemoradiotherapy. OS of HPV-associated and HPV-negative patients was compared using Kaplan-Meier and multivariable Cox regression analyses. Results: The majority of OSCC patients (215 of 361; 69.5%) received upfront surgery as first-line treatment in curative intent. The 5-year OS rate in patients with HPV-positive and HPV-negative tumors were 81.1 and 39.7%, respectively. Upfront surgery in HPV-negative (p < 0.001) and HPV-positive patients (p = 0.05) resulted in improved OS only in advanced stages. Multivariate analysis for patients revealed age in HPV-associated OSCC as an independent predictor for improved survival, and age, performance, N status and therapy as independent predictors in HPV-negative OSCC. Conclusions: Non-selected OSCC patients amenable to curative therapy show poor 5-year OS. The benefit of upfront surgery remains unclear. A younger patient age was the main factor for a better outcome in patients with HPV-associated OSCC.

5-aza-2’-deoxycytidine (DAC) treatment downregulates the HPV E6 and E7 oncogene expression and blocks neoplastic growth of HPV-associated cancer cells

High-risk human papillomaviruses (hr HPVs) may cause various human cancers and associated premalignant lesions. Transformation of the host cells is triggered by overexpression of the viral oncogenes E6 and E7 that deregulate the cell cycle and induce chromosomal instability. This process is accompanied by hypermethylation of distinct CpG sites resulting in silencing of tumor suppressor genes, inhibition of the viral E2 mediated control of E6 and E7 transcription as well as deregulated expression of host cell microRNAs. Therefore, we hypothesized that treatment with demethylating agents might restore those regulatory mechanisms. Here we show that treatment with 5-aza-2′-deoxycytidine (DAC) strongly decreases the expression of E6 and E7 in a panel of HPV-transformed cervical cancer and head and neck squamous cell carcinoma cell lines. Reduction of E6 and E7 further resulted in increased target protein levels including p53 and p21 reducing the proliferation rates and colony formation abilities of the treated cell lines. Moreover, DAC treatment led to enhanced expression of tumor the suppressive miRNA-375 that targets and degrades E6 and E7 transcripts. Therefore, we suggest that DAC treatment of HPV-associated cancers and respective precursor lesions may constitute a targeted approach to subvert HPV oncogene functions that deserves testing in clinical trials.

Humane Papillomviren bei Plattenepithelkarzinomen der Kopf- und Halsregion

Human papilloma viruses (HPV) are responsible for approximately half of all oropharyngeal squamous cell carcinomas (OPSCC) and incidence rates of HPV-associated OPSCC continue to increase substantially. The defined viral carcinogenesis permits development of specific diagnostic, therapeutic, and prophylactic approaches. Laboratory identification of HPV-associated OPSCC may be achieved by p16(INK4a) immunohistochemistry combined with HPV DNA detection by polymerase chain reaction (PCR) using tumor tissue. Patients with HPV-associated OPSCC have a relatively good prognosis; therefore, the HPV status plays an important role in patient guidance. Due to the relatively favorable prognosis, ongoing studies are evaluating whether less rigorous therapy for HPV-positive patients results in equally good cure rates. The criteria for patient selection are, however, still uncertain. Particularly markers for detection of HPV-positive patients with a high risk of treatment failure are lacking. Besides tumor stage and comorbidities, distinct genomic, epigenetic, and immunologic alterations are prognostically relevant for HPV-associated OPSCC, and might be of predictive value. Furthermore, the characteristic molecular alterations suggest the possibility of novel vigilant and specific therapy approaches. These may be inhibitors of the phosphatidylinositol 3‑kinase (PI3K) pathway, which is frequently activated in HPV-associated OPSCC, and immunotherapeutic methods, e. g., therapeutic vaccination. Although prophylactic HPV vaccinations may also prevent development of HPV-associated OPSCC, foreseeable effects on OPSCC incidence will be low, given the low vaccination rates in Germany. This highlights the fact that interdisciplinary research networks should enhance the necessary activities related to HPV-associated OPSCC.ZusammenfassungHumane Papillomviren (HPV) verursachen bereits etwa die Hälfte aller Oropharynxkarzinome („oropharyngeal squamous cell carcinoma“, OPSCC) und die Neuerkrankungsrate HPV-assoziierter OPSCC steigt weiter stark an. Die virale Ursache ermöglicht die Entwicklung spezifischer diagnostischer, therapeutischer und prophylaktischer Verfahren. Die labortechnische Identifizierung eines HPV-assoziierten OPSCC kann durch die p16INK4a-Immunhistologie kombiniert mit einem HPV-DNA-Nachweis mittels Polymerasekettenreaktion (PCR) aus Tumorgewebe erfolgen. Patienten mit HPV-assoziierten OPSCC haben eine relativ gute Prognose, daher spielt die Feststellung der HPV-Assoziation in der Patientenberatung eine wichtige Rolle. Aufgrund der relativ günstigen Prognose wird in laufenden Studien geprüft, ob mit einer weniger intensiven Therapie für HPV-positive Patienten gleiche Heilungsraten erreicht werden können. Die Kriterien für eine Selektion geeigneter Patienten sind allerdings noch unklar. Insbesondere fehlen bisher Marker zur Erkennung HPV-positiver Patienten mit hohem Risiko für Therapieversagen. Neben dem Tumorstadium und der Komorbidität sind bei HPV-assoziierten OSPCC bestimmte genomische, epigenetische und immunologische Veränderungen prognostisch relevant und könnten einen prädiktiven Nutzen haben. Die charakteristischen Veränderungen auf molekularer Ebene lassen zudem neue schonendere und spezifischere Therapieansätze möglich erscheinen. Hierzu gehören Inhibitoren des bei HPV-assoziierten OPSCC häufig aktivierten Phosphatidylinositol-3-Kinase(PI3K)-Signalwegs sowie immuntherapeutische Verfahren, z. B. die therapeutische Impfung. Obwohl die prophylaktische HPV-Impfung auch die Entstehung HPV-assoziierter OPSCC verhindern kann, wird der Effekt auf die Inzidenz von OPSCC mit den in Deutschland niedrigen Impfraten in absehbarer Zeit gering sein. Dies verdeutlicht, dass interdisziplinäre Forschungsnetzwerke die notwendige Aktivität zu HPV-assoziierten OPSCC verstärkt sicherstellen sollten.AbstractHuman papilloma viruses (HPV) are responsible for approximately half of all oropharyngeal squamous cell carcinomas (OPSCC) and incidence rates of HPV-associated OPSCC continue to increase substantially. The defined viral carcinogenesis permits development of specific diagnostic, therapeutic, and prophylactic approaches. Laboratory identification of HPV-associated OPSCC may be achieved by p16INK4a immunohistochemistry combined with HPV DNA detection by polymerase chain reaction (PCR) using tumor tissue. Patients with HPV-associated OPSCC have a relatively good prognosis; therefore, the HPV status plays an important role in patient guidance. Due to the relatively favorable prognosis, ongoing studies are evaluating whether less rigorous therapy for HPV-positive patients results in equally good cure rates. The criteria for patient selection are, however, still uncertain. Particularly markers for detection of HPV-positive patients with a high risk of treatment failure are lacking. Besides tumor stage and comorbidities, distinct genomic, epigenetic, and immunologic alterations are prognostically relevant for HPV-associated OPSCC, and might be of predictive value. Furthermore, the characteristic molecular alterations suggest the possibility of novel vigilant and specific therapy approaches. These may be inhibitors of the phosphatidylinositol 3‑kinase (PI3K) pathway, which is frequently activated in HPV-associated OPSCC, and immunotherapeutic methods, e. g., therapeutic vaccination. Although prophylactic HPV vaccinations may also prevent development of HPV-associated OPSCC, foreseeable effects on OPSCC incidence will be low, given the low vaccination rates in Germany. This highlights the fact that interdisciplinary research networks should enhance the necessary activities related to HPV-associated OPSCC.

Humane Papillomviren bei Plattenepithelkarzinomen der Kopf- und Halsregion@@@Human papillomavirus and squamous cell cancer of the head and neck region: Relevanz für Prognose, Therapie und Prophylaxe@@@Prognostic, therapeutic and prophylactic implications

Human papilloma viruses (HPV) are responsible for approximately half of all oropharyngeal squamous cell carcinomas (OPSCC) and incidence rates of HPV-associated OPSCC continue to increase substantially. The defined viral carcinogenesis permits development of specific diagnostic, therapeutic, and prophylactic approaches. Laboratory identification of HPV-associated OPSCC may be achieved by p16(INK4a) immunohistochemistry combined with HPV DNA detection by polymerase chain reaction (PCR) using tumor tissue. Patients with HPV-associated OPSCC have a relatively good prognosis; therefore, the HPV status plays an important role in patient guidance. Due to the relatively favorable prognosis, ongoing studies are evaluating whether less rigorous therapy for HPV-positive patients results in equally good cure rates. The criteria for patient selection are, however, still uncertain. Particularly markers for detection of HPV-positive patients with a high risk of treatment failure are lacking. Besides tumor stage and comorbidities, distinct genomic, epigenetic, and immunologic alterations are prognostically relevant for HPV-associated OPSCC, and might be of predictive value. Furthermore, the characteristic molecular alterations suggest the possibility of novel vigilant and specific therapy approaches. These may be inhibitors of the phosphatidylinositol 3‑kinase (PI3K) pathway, which is frequently activated in HPV-associated OPSCC, and immunotherapeutic methods, e. g., therapeutic vaccination. Although prophylactic HPV vaccinations may also prevent development of HPV-associated OPSCC, foreseeable effects on OPSCC incidence will be low, given the low vaccination rates in Germany. This highlights the fact that interdisciplinary research networks should enhance the necessary activities related to HPV-associated OPSCC.ZusammenfassungHumane Papillomviren (HPV) verursachen bereits etwa die Hälfte aller Oropharynxkarzinome („oropharyngeal squamous cell carcinoma“, OPSCC) und die Neuerkrankungsrate HPV-assoziierter OPSCC steigt weiter stark an. Die virale Ursache ermöglicht die Entwicklung spezifischer diagnostischer, therapeutischer und prophylaktischer Verfahren. Die labortechnische Identifizierung eines HPV-assoziierten OPSCC kann durch die p16INK4a-Immunhistologie kombiniert mit einem HPV-DNA-Nachweis mittels Polymerasekettenreaktion (PCR) aus Tumorgewebe erfolgen. Patienten mit HPV-assoziierten OPSCC haben eine relativ gute Prognose, daher spielt die Feststellung der HPV-Assoziation in der Patientenberatung eine wichtige Rolle. Aufgrund der relativ günstigen Prognose wird in laufenden Studien geprüft, ob mit einer weniger intensiven Therapie für HPV-positive Patienten gleiche Heilungsraten erreicht werden können. Die Kriterien für eine Selektion geeigneter Patienten sind allerdings noch unklar. Insbesondere fehlen bisher Marker zur Erkennung HPV-positiver Patienten mit hohem Risiko für Therapieversagen. Neben dem Tumorstadium und der Komorbidität sind bei HPV-assoziierten OSPCC bestimmte genomische, epigenetische und immunologische Veränderungen prognostisch relevant und könnten einen prädiktiven Nutzen haben. Die charakteristischen Veränderungen auf molekularer Ebene lassen zudem neue schonendere und spezifischere Therapieansätze möglich erscheinen. Hierzu gehören Inhibitoren des bei HPV-assoziierten OPSCC häufig aktivierten Phosphatidylinositol-3-Kinase(PI3K)-Signalwegs sowie immuntherapeutische Verfahren, z. B. die therapeutische Impfung. Obwohl die prophylaktische HPV-Impfung auch die Entstehung HPV-assoziierter OPSCC verhindern kann, wird der Effekt auf die Inzidenz von OPSCC mit den in Deutschland niedrigen Impfraten in absehbarer Zeit gering sein. Dies verdeutlicht, dass interdisziplinäre Forschungsnetzwerke die notwendige Aktivität zu HPV-assoziierten OPSCC verstärkt sicherstellen sollten.AbstractHuman papilloma viruses (HPV) are responsible for approximately half of all oropharyngeal squamous cell carcinomas (OPSCC) and incidence rates of HPV-associated OPSCC continue to increase substantially. The defined viral carcinogenesis permits development of specific diagnostic, therapeutic, and prophylactic approaches. Laboratory identification of HPV-associated OPSCC may be achieved by p16INK4a immunohistochemistry combined with HPV DNA detection by polymerase chain reaction (PCR) using tumor tissue. Patients with HPV-associated OPSCC have a relatively good prognosis; therefore, the HPV status plays an important role in patient guidance. Due to the relatively favorable prognosis, ongoing studies are evaluating whether less rigorous therapy for HPV-positive patients results in equally good cure rates. The criteria for patient selection are, however, still uncertain. Particularly markers for detection of HPV-positive patients with a high risk of treatment failure are lacking. Besides tumor stage and comorbidities, distinct genomic, epigenetic, and immunologic alterations are prognostically relevant for HPV-associated OPSCC, and might be of predictive value. Furthermore, the characteristic molecular alterations suggest the possibility of novel vigilant and specific therapy approaches. These may be inhibitors of the phosphatidylinositol 3‑kinase (PI3K) pathway, which is frequently activated in HPV-associated OPSCC, and immunotherapeutic methods, e. g., therapeutic vaccination. Although prophylactic HPV vaccinations may also prevent development of HPV-associated OPSCC, foreseeable effects on OPSCC incidence will be low, given the low vaccination rates in Germany. This highlights the fact that interdisciplinary research networks should enhance the necessary activities related to HPV-associated OPSCC.

Humane Papillomviren bei Plattenepithelkarzinomen der Kopf- und Halsregion: Relevanz für Prognose, Therapie und Prophylaxe

Human papilloma viruses (HPV) are responsible for approximately half of all oropharyngeal squamous cell carcinomas (OPSCC) and incidence rates of HPV-associated OPSCC continue to increase substantially. The defined viral carcinogenesis permits development of specific diagnostic, therapeutic, and prophylactic approaches. Laboratory identification of HPV-associated OPSCC may be achieved by p16(INK4a) immunohistochemistry combined with HPV DNA detection by polymerase chain reaction (PCR) using tumor tissue. Patients with HPV-associated OPSCC have a relatively good prognosis; therefore, the HPV status plays an important role in patient guidance. Due to the relatively favorable prognosis, ongoing studies are evaluating whether less rigorous therapy for HPV-positive patients results in equally good cure rates. The criteria for patient selection are, however, still uncertain. Particularly markers for detection of HPV-positive patients with a high risk of treatment failure are lacking. Besides tumor stage and comorbidities, distinct genomic, epigenetic, and immunologic alterations are prognostically relevant for HPV-associated OPSCC, and might be of predictive value. Furthermore, the characteristic molecular alterations suggest the possibility of novel vigilant and specific therapy approaches. These may be inhibitors of the phosphatidylinositol 3‑kinase (PI3K) pathway, which is frequently activated in HPV-associated OPSCC, and immunotherapeutic methods, e. g., therapeutic vaccination. Although prophylactic HPV vaccinations may also prevent development of HPV-associated OPSCC, foreseeable effects on OPSCC incidence will be low, given the low vaccination rates in Germany. This highlights the fact that interdisciplinary research networks should enhance the necessary activities related to HPV-associated OPSCC.ZusammenfassungHumane Papillomviren (HPV) verursachen bereits etwa die Hälfte aller Oropharynxkarzinome („oropharyngeal squamous cell carcinoma“, OPSCC) und die Neuerkrankungsrate HPV-assoziierter OPSCC steigt weiter stark an. Die virale Ursache ermöglicht die Entwicklung spezifischer diagnostischer, therapeutischer und prophylaktischer Verfahren. Die labortechnische Identifizierung eines HPV-assoziierten OPSCC kann durch die p16INK4a-Immunhistologie kombiniert mit einem HPV-DNA-Nachweis mittels Polymerasekettenreaktion (PCR) aus Tumorgewebe erfolgen. Patienten mit HPV-assoziierten OPSCC haben eine relativ gute Prognose, daher spielt die Feststellung der HPV-Assoziation in der Patientenberatung eine wichtige Rolle. Aufgrund der relativ günstigen Prognose wird in laufenden Studien geprüft, ob mit einer weniger intensiven Therapie für HPV-positive Patienten gleiche Heilungsraten erreicht werden können. Die Kriterien für eine Selektion geeigneter Patienten sind allerdings noch unklar. Insbesondere fehlen bisher Marker zur Erkennung HPV-positiver Patienten mit hohem Risiko für Therapieversagen. Neben dem Tumorstadium und der Komorbidität sind bei HPV-assoziierten OSPCC bestimmte genomische, epigenetische und immunologische Veränderungen prognostisch relevant und könnten einen prädiktiven Nutzen haben. Die charakteristischen Veränderungen auf molekularer Ebene lassen zudem neue schonendere und spezifischere Therapieansätze möglich erscheinen. Hierzu gehören Inhibitoren des bei HPV-assoziierten OPSCC häufig aktivierten Phosphatidylinositol-3-Kinase(PI3K)-Signalwegs sowie immuntherapeutische Verfahren, z. B. die therapeutische Impfung. Obwohl die prophylaktische HPV-Impfung auch die Entstehung HPV-assoziierter OPSCC verhindern kann, wird der Effekt auf die Inzidenz von OPSCC mit den in Deutschland niedrigen Impfraten in absehbarer Zeit gering sein. Dies verdeutlicht, dass interdisziplinäre Forschungsnetzwerke die notwendige Aktivität zu HPV-assoziierten OPSCC verstärkt sicherstellen sollten.AbstractHuman papilloma viruses (HPV) are responsible for approximately half of all oropharyngeal squamous cell carcinomas (OPSCC) and incidence rates of HPV-associated OPSCC continue to increase substantially. The defined viral carcinogenesis permits development of specific diagnostic, therapeutic, and prophylactic approaches. Laboratory identification of HPV-associated OPSCC may be achieved by p16INK4a immunohistochemistry combined with HPV DNA detection by polymerase chain reaction (PCR) using tumor tissue. Patients with HPV-associated OPSCC have a relatively good prognosis; therefore, the HPV status plays an important role in patient guidance. Due to the relatively favorable prognosis, ongoing studies are evaluating whether less rigorous therapy for HPV-positive patients results in equally good cure rates. The criteria for patient selection are, however, still uncertain. Particularly markers for detection of HPV-positive patients with a high risk of treatment failure are lacking. Besides tumor stage and comorbidities, distinct genomic, epigenetic, and immunologic alterations are prognostically relevant for HPV-associated OPSCC, and might be of predictive value. Furthermore, the characteristic molecular alterations suggest the possibility of novel vigilant and specific therapy approaches. These may be inhibitors of the phosphatidylinositol 3‑kinase (PI3K) pathway, which is frequently activated in HPV-associated OPSCC, and immunotherapeutic methods, e. g., therapeutic vaccination. Although prophylactic HPV vaccinations may also prevent development of HPV-associated OPSCC, foreseeable effects on OPSCC incidence will be low, given the low vaccination rates in Germany. This highlights the fact that interdisciplinary research networks should enhance the necessary activities related to HPV-associated OPSCC.

Abstract 828: Methylation status of HPV16 E2-binding sites identifies subtypes of HPV-associated oropharyngeal squamous cell carcinomas

Background: The viral E2 protein is a transcriptional repressor of the HPV oncogenes E6/E7 and loss of E2 function is considered a key step in carcinogenesis. Integration of HPV into the host genome may disrupt the E2 gene. Furthermore, methylation of CpG dinucleotides in E2 binding sites (E2BSs) in the HPV upstream regulatory region (URR) may interfere with transcriptional repression of E6 and E7 by the E2 protein. We hypothesized that CpG methylation of the E2BS is found in a proportion of HPV16-associated oropharyngeal squamous cell cancers (OPSCC) in association with E2 gene integrity and viral integration. Methods: Methylation of 10 CpGs within the URR, encompassing E2BSs 1, 2, 3 and 4, was quantitatively analyzed by bisulfite pyrosequencing in 57 HPV16-associated OPSCC. E2 status was analyzed by gene amplification and quantitative real-time RT-PCR. Viral integration was determined by integration-specific PCR methods. Results: Three subgroups with differential E2BSs3 and 4 methylation were identified: a) complete methylation (>80%) associated with presence of integrated HPV genomes with intact E2 gene, b) intermediate methylation levels (20-80%) with predominantly episomal HPV genomes with intact E2, and c) no methylation ( Conclusions: E2BSs3 and 4 methylation in oropharyngeal cancers with episomal HPV and integrated HPV with intact E2 gene might explain deregulated viral oncogene expression in the presence of E2. The methylation level appears to be of prognostic significance for patients with HPV-associated OPSCC. Citation Format: Ernst-Jan M. Speel, Miriam Reuschenbach, Christian U. Huebbers, Elena-Sophie Prigge, Justo L. Bermejo, Simon Kalteis, Simon Preuss, Jutta Kolligs, Nadine C. Olthof, Bernd Kremer, Steffen Wagner, Jens P. Klussmann, Svetlana Vinokurova, Magnus von Knebel Doeberitz. Methylation status of HPV16 E2-binding sites identifies subtypes of HPV-associated oropharyngeal squamous cell carcinomas. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 828. doi:10.1158/1538-7445.AM2015-828

Abstract A18: Defining ovarian mucinous tumors: Cancer genes and heterogeneity

Background: Mucinous ovarian carcinomas (MC) and mucinous borderline ovarian tumours (MBOT) are associated with ERBB2 amplification and KRAS activating mutations. These events occur in a near-mutually exclusive pattern, and KRAS mutations are more prevalent in MBOTs than MC9s whereas ERBB2 amplification is more frequently seen in MCs. Frequencies of mutations in other oncogenes and tumour suppressor genes in MC are not well established though TP53, BRAF, NRAS, and CDKN2A mutations have all been reported. As these carcinomas are commonly chemo-resistant a definitive molecular categorization of this subtype is needed as treatment options are explored. Methods: We undertook review of pathology reports and after exclusion of potential gastric, appendiceal or pancreatic involvement over 100 mucinous ovarian tumours were identified. HPV testing was undertaken to exclude rare metastasis from endocervical primary site. All specimens were assayed for p53 expression via TMA and subject to sequencing of common cancer gene hotspots using Ion-Torrent or Illumina MiSeq. Previously derived data on ERBB2 status was combined in our analysis and, where available, samples showing heterogeneity of ERBB2 amplification and any other Ras-pathway activating mutation were microdissected with components evaluated independently for concurrent hotspot mutations. Results: All samples were consistent with mucinous tumours of ovarian origin and none were HPV positive. We detected mutations in KRAS, BRAF, CDKN2A, TP53, PTEN, PIK3CA as well as presumed somatic/detrimental, variants in APC that have not previously been reported in mucinous tumours. Despite some samples having enriched tumour content, lower than expected allelic frequencies of KRAS activating mutations suggested intra-tumoural heterogeneity. This was consistent with results observed previously with rare ERBB2 amplification coinciding KRAS mutations. Conclusions: The prevalence of Ras-pathway mutations, especially amongst borderline lesions, suggests these mutations are critical for tumour onset. However varying allelic frequencies of KRAS mutations suggest progression to carcinoma is strongly influenced by other molecular features. Citation Format: Michael S. Anglesio, Robertson Mackenzie, Stefan Kommoss, Boris J. Winterhoff, Benjamin Kipp, Jaoquin Garcia, Jesse S. Voss, Kevin Halling, Sarah Kerr, Janine Senz, Winnie Yang, Magnus von Knebel Doeberitz, Elena-Sophie Prigge, Miriam Reuschenbach, Anna V. Tinker, Blake Gilks, Jamie N. Bakkum-Gamez, David G. Huntsman, Jessica N. McAlpine. Defining ovarian mucinous tumors: Cancer genes and heterogeneity. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr A18.