EB病毒能排除鼻咽癌吗
近日，香港中文大学的卢煜明（Dennis Lo）教授团队，基于液态活检技术，通过检测Epstein-Barr病毒的DNA，在鼻咽癌筛查中进行尝试，结果可提高该疾病的早期检测和生存率。表明此方法至少对于这种在当地普遍存在的癌症是有效的。该项研究于8月10日在线发表在新英格兰医学杂志（NEJM）上。
总共有20174名40~62岁的受试者接受了EBV DNA筛查，1112人（5.5%）在血浆样本中检测到EBV DNA。
309人（占所有受试人群的1.5%，最初检测为阳性人群的27.8%）重复检测的结果持续为阳性。在这309名受试者中，有300人进一步接受内镜检查，275人接受了内镜检查和MRI检查；其中34人（11%）诊断为鼻咽癌。在筛查出的鼻咽癌患者中，I期或II期鼻咽癌的患者比例明显高于历史对照组（71% vs. 20%，P < 0.001），大约半数（n=16 [47%]）为I期，显著高于既往文献报道的5%~7%。筛查后诊断为鼻咽癌的患者，其3年无进展生存率优于历史对照组（97% vs. 70%；P＜0.001）。
9名受试者拒绝接受进一步的检查，其中1人在入组32个月后发生鼻咽癌晚期。在筛查后1年内，仅1名血浆样本EBV DNA检测阴性的受试者出现鼻咽癌。血浆中EBV DNA在鼻咽癌筛查中的敏感性和特异性分别为97.1%和98.6%。
图：鼻咽癌阶段的分布和生存率的变化
研究结论：血浆样本EBV DNA分析有助于早期无症状鼻咽癌的筛查。EBV DNA筛查使鼻咽癌更早被发现，患者结局明显优于历史对照组。
（本研究由嘉道理慈善基金会及香港研究资助局资助）
K.C. Allen Chan, et al. Analysis of Plasma Epstein–Barr Virus DNA to Screen for Nasopharyngeal Cancer. N Engl J Med 2017; 377:513-522.
BACKGROUND:Circulating cell-free Epstein-Barr virus (EBV) DNA is a biomarker for nasopharyngeal carcinoma. We conducted a prospective study to investigate whether EBV DNA in plasma samples would be useful to screen for early nasopharyngeal carcinoma in asymptomatic persons.METHODS:We analyzed EBV DNA in plasma specimens to screen participants who did not have symptoms of nasopharyngeal carcinoma. Participants with initially positive results were retested approximately 4 weeks later, and those with persistently positive EBV DNA in plasma underwent nasal endoscopic examination and magnetic resonance imaging (MRI).RESULTS:A total of 20,174 participants underwent screening. EBV DNA was detectable in plasma samples obtained from 1112 participants (5.5%), and 309 (1.5% of all participants and 27.8% of those who initially tested positive) had persistently positive results on the repeated sample. Among these 309 participants, 300 underwent endoscopic examination, and 275 underwent both endoscopic examination and MRI; of these participants, 34 had nasopharyngeal carcinoma. A significantly higher proportion of participants with nasopharyngeal carcinoma that was identified by screening had stage I or II disease than in a historical cohort (71% vs. 20%, P<0.001 by the chi-square test) and had superior 3-year progression-free survival (97% vs. 70%; hazard ratio, 0.10; 95% confidence interval, 0.05 to 0.18). Nine participants declined to undergo further testing, and 1 of them presented with advanced nasopharyngeal carcinoma 32 months after enrollment. Nasopharyngeal carcinoma developed in only 1 participant with negative EBV DNA in plasma samples within 1 year after testing. The sensitivity and specificity of EBV DNA in plasma samples in screening for nasopharyngeal carcinoma were 97.1% and 98.6%, respectively.
CONCLUSIONS:Analysis of EBV DNA in plasma samples was useful in screening for early asymptomatic nasopharyngeal carcinoma. Nasopharyngeal carcinoma was detected significantly earlier and outcomes were better in participants who were identified by screening than in those in a historical cohort. (Funded by the Kadoorie Charitable Foundation and the Research Grants Council of the Hong Kong government; ClinicalTrials.gov number, NCT02063399 .).
