title: Previous tonsillectomy modifies odds of tonsil and base of tongue cancer.
abstract: BACKGROUND
  Tonsillectomy is a commonly performed surgical procedure that involves removal of the palatine tonsils. The purpose of this study is to examine the association between previous tonsillectomy and odds of oropharyngeal squamous cell carcinoma (OPSCC) in a large population-based case-control study. We hypothesise that previous tonsillectomy is associated with a decreased odds of tonsil cancer with no impact on the odds of developing base of tongue (BOT) cancer.
  
  
  METHODS
  This was a population-based, frequency-matched case-control study with multinomial logistic regression, including 1378 controls, 108 BOT cancer cases, and 198 tonsil cancer cases. Demographic and risk factor data were collected using a structured questionnaire during an in-home visit conducted by trained nurse-interviewers. The human papillomavirus (HPV) tumour status was determined through Luminex-based multiplex PCR and p16 status by immunohistochemistry.
  
  
  RESULTS
  Previous tonsillectomy was associated with a nearly two-fold increased odds of BOT cancer (OR=1.95, 95% CI 1.25-3.06, P=0.003) and a large decrease in the odds of tonsil cancer (OR=0.22, 95% CI 0.13-0.36, P<0.001). When HPV status was considered, tonsillectomy was associated with a decreased odds of HPV-positive tonsil cancer (OR=0.17, 95% CI 0.08-0.34, P<0.001) and an increased risk of HPV-positive BOT cancer (OR=2.46, 95% CI 1.22-4.95, P=0.012). When p16 status was considered, tonsillectomy was associated with an increased odds of p16-positive BOT cancer (OR=2.24, 95% CI 1.16-4.35, P=0.017) and a decreased odds of p16-positive tonsil cancer (OR=0.14, 95% CI 0.07-0.31, P<0.001).
  
  
  CONCLUSIONS
  Previous tonsillectomy modifies the odds of both tonsil and BOT cancer, with decreased odds of tonsil cancer and increased odds of BOT cancer. A history of previous tonsillectomy may play a role in OPSCC risk stratification when considered along with other covariates such as sexual history, smoking status, and age.
authors.affiliation: Department of Otolaryngology/Head and Neck Surgery, University of North Carolina at Chapel Hill School of Medicine, 170 Manning Drive, CB 7070, Chapel Hill, NC 27599, USA.|Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.|Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Jose P
authors.initials: JP
authors.lastname: Zevallos
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Angela L
authors.initials: AL
authors.lastname: Mazul
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Nidia
authors.initials: N
authors.lastname: Rodriguez
authors.affiliation: Department of Otolaryngology/Head and Neck Surgery, University of North Carolina at Chapel Hill School of Medicine, 170 Manning Drive, CB 7070, Chapel Hill, NC 27599, USA.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Weissler
authors.affiliation: International Agency for Research on Cancer (IARC), Lyon, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Brennan
authors.affiliation: International Agency for Research on Cancer (IARC), Lyon, France.
authors.forename: Devasena
authors.initials: D
authors.lastname: Anantharaman
authors.affiliation: International Agency for Research on Cancer (IARC), Lyon, France.
authors.forename: Behnoush
authors.initials: B
authors.lastname: Abedi-Ardekani
authors.affiliation: Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: D
authors.initials: D
authors.lastname: Neil Hayes
authors.affiliation: Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.|Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Olshan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000453:epidemiology* / Q000601:surgery / Q000821:virology; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000453:epidemiology* / Q000601:surgery / Q000821:virology; D006801:Humans; D008297:Male; D008875:Middle Aged; D014066:Palatine Tonsil / Q000601:surgery* / Q000821:virology; D027383:Papillomaviridae / Q000302:isolation & purification; D030361:Papillomavirus Infections / Q000453:epidemiology* / Q000601:surgery / Q000821:virology; D011379:Prognosis; D014062:Tongue Neoplasms / Q000453:epidemiology* / Q000601:surgery / Q000821:virology; D014068:Tonsillectomy; D055815:Young Adult