title: Conisation as a marker of persistent human papilloma virus infection and risk of breast cancer.
abstract: Human papillomavirus (HPV) infection may increase breast cancer (BC) risk.
  
  
  
  To examine this, we used nationwide medical registries to identify all Danish women who underwent conisation to remove HPV-associated cervical precancerous lesions (n=87 782) from 1978 to 2013. We computed the absolute risk of BC and standardised incidence ratios (SIRs) and 95% confidence intervals (95% CIs) for breast cancer, based on national breast cancer incidence rates.
  
  
  
  Conisation was associated with slightly increased BC incidence (SIR=1.1, 95% CI=1.0-1.1), and an absolute BC risk of 7.7% (95% CI=7.3-8.1%) in 35.9 years of follow-up. BC risk was elevated throughout follow-up, especially in the first 5 years (<1 year: SIR=1.2, 95% CI=0.92-1.5; 1-5 years: SIR=1.2, 95% CI=1.1-1.3; ⩾5 years: SIR=1.1, 95% CI=1.0-1.1). Women who underwent conisation and had autoimmune disease had elevated BC risk after 5 years of follow-up (SIR=1.4, 95% CI=1.0-1.8).
  
  
  
  BC risk is slightly elevated in women with persistent HPV infection, possibly due to detection bias.
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus N, 8200 Aarhus N, Denmark.
authors.forename: Mette
authors.initials: M
authors.lastname: Søgaard
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus N, 8200 Aarhus N, Denmark.
authors.forename: Dora K
authors.initials: DK
authors.lastname: Farkas
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus N, 8200 Aarhus N, Denmark.
authors.forename: Anne G
authors.initials: AG
authors.lastname: Ording
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus N, 8200 Aarhus N, Denmark.
authors.forename: Henrik T
authors.initials: HT
authors.lastname: Sørensen
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus N, 8200 Aarhus N, Denmark.
authors.forename: Deirdre
authors.initials: D
authors.lastname: P Cronin-Fenton
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000150:complications*; D019092:Conization; D003718:Denmark; D005260:Female; D006801:Humans; D030361:Papillomavirus Infections / Q000150:complications / Q000453:epidemiology*; D012307:Risk Factors; D002583:Uterine Cervical Neoplasms / Q000150:complications / Q000628:therapy*