title: Interval cancers in nasopharyngeal carcinoma screening: comparing two screening intervals after a negative initial screening result.
abstract: OBJECTIVE
  To examine the optimal screening interval among the individuals who received a negative Epstein-Barr virus immunoglobulin A antibodies against viral capsid antigen (VCA-IgA) serum test result and who comprised the majority of the population screened for nasopharyngeal carcinoma (NPC).
  
  
  METHODS
  Screening was performed in Sihui, Guangdong, China, offering a repeated screening for participants with an initial negative test either after 4-5 years in one centre (short interval centre), or 9-10 years in another (long interval centre). The characteristics and incidence rates (IRs) of interval NPCs (defined as cases diagnosed outside the screening protocol while within the screening interval) were compared between these two centres. Standard incidence ratios (SIRs) were also calculated using the general Sihui population as the reference.
  
  
  RESULTS
  Seven interval NPCs were detected in the short interval centre (IR: 17.8/10(5) person-years) and 20 in the long interval centre (IR: 20.8/10(5) person-years during the first four years and 43.5/10(5) person-years during the remaining years). The SIR in the short interval centre was 0.43 (95% confidence interval [CI]: 0.17-0.89); SIR in the long interval centre was 0.47 (95% CI: 0.17-1.02) during the first four years and 0.90 (95% CI: 0.49-1.51) during the remaining years. No aggressive interval NPC was observed in the short interval centre; four were identified in the long interval centre.
  
  
  CONCLUSIONS
  The incidence of NPC, especially aggressive NPC, was low during the first few years after a negative screening; the incidence increased to the general population level afterwards. A screening interval of 4-5 years may therefore be more suitable than 9-10 years after a negative VCA-IgA test in NPC screening.
authors.affiliation: State Key Laboratory of Oncology in Southern China, and Department of Epidemiology, Cancer Prevention Center, Sun Yat-Sen University Cancer Center, Guangzhou, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Chen
authors.forename: Qi-Hong
authors.initials: QH
authors.lastname: Huang
authors.forename: Fang
authors.initials: F
authors.lastname: Fang
authors.forename: Zhi-Wei
authors.initials: ZW
authors.lastname: Liu
authors.forename: Ke
authors.initials: K
authors.lastname: Liu
authors.forename: Shang-Hang
authors.initials: SH
authors.lastname: Xie
authors.forename: Qing
authors.initials: Q
authors.lastname: Liu
authors.forename: Ming-Huang
authors.initials: MH
authors.lastname: Hong
authors.forename: Zhen-Er
authors.initials: ZE
authors.lastname: Liao
authors.forename: Wei-Min
authors.initials: WM
authors.lastname: Ye
authors.forename: Yi-Xin
authors.initials: YX
authors.lastname: Zeng
authors.forename: Su-Mei
authors.initials: SM
authors.lastname: Cao
mesh_terms: D000328:Adult; D000914:Antibodies, Viral / Q000097:blood; D000956:Antigens, Viral / Q000276:immunology; D002277:Carcinoma; D002681:China / Q000453:epidemiology; D055088:Early Detection of Cancer / Q000706:statistics & numerical data*; D020031:Epstein-Barr Virus Infections / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology / Q000276:immunology; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D015994:Incidence; D008297:Male; D008875:Middle Aged; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology / Q000821:virology; D009369:Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology / Q000276:immunology; D013997:Time Factors
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral; D007070:Immunoglobulin A