Abstract PL04-01: Screening for nasopharyngeal carcinoma using plasma Epstein-Barr virus DNA: Technological and clinical insights

Abstract

Abstract Epstein-Barr virus (EBV) DNA is released by a number of EBV-associated malignancies into the plasma. Examples of such malignancies include nasopharyngeal carcinoma (NPC), certain lymphomas and EBV-associated gastric carcinoma. Plasma EBV DNA in such malignancies exhibits a strong correlation with tumor stage, clinical progress and prognosis; and is thus an archetypal circulating tumor DNA species. Our group is interested in exploring the use of plasma EBV DNA to screen for NPC. We have recently completed a prospective population screening project involving over 20,000 middle aged men in Hong Kong. Using plasma EBV DNA as a screening tool, NPC could be found at a much earlier stage than was normally possible. Furthermore, the prognosis of the NPC patients identified through such screening was much more favorable than those diagnosed without such screening. The positive predictive value of this approach was 11%. False-positive results were observed a proportion of subjects without NPC. Factors that contributed to increased false-positive results included advancing age and surprisingly, the ambient temperature of the day when samples were collected. Hence, a higher percentage of false-positive results were observed when samples were collected in colder weather. We hypothesized that such results might be related to the fluctuations in the effectiveness of the immune system in certain individuals due to ambient temperature. Since the reporting of the above-mentioned results, we have been exploring approaches for further enhancing the positive predictive value. Through the use of targeted massively parallel paired-end sequencing, we found that the size profiles of plasma EBV DNA in subjects with NPC and those without were different. Indeed, by combining such size profile and the concentration of plasma EBV DNA as measured by sequencing, the positive predictive value could be further enhanced. Very recently, we investigated the epigenetic profile of plasma EBV DNA in subjects with NPC and those without cancer, in an attempt to further enhance the positive predictive value of the approach. We believe that the development of a robust approach for NPC screening using circulating EBV DNA would have major public health impact, allowing the earlier detection and treatment of NPC in high prevalence areas. We also believe that such developments would also guide the development of other circulating tumor DNA markers for early cancer detection. Citation Format: Yuk Ming Dennis Lo. Screening for nasopharyngeal carcinoma using plasma Epstein-Barr virus DNA: Technological and clinical insights [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 PL04-01.