title: The population impact of human papillomavirus/cytology cervical cotesting at 3-year intervals: Reduced cervical cancer risk and decreased yield of precancer per screen.
abstract: BACKGROUND
  The objective of cervical screening is to detect and treat precancer to prevent cervical cancer mortality and morbidity while minimizing overtreatment of benign human papillomavirus (HPV) infections and related minor abnormalities. HPV/cytology cotesting at extended 5-year intervals currently is a recommended screening strategy in the United States, but the interval extension is controversial. In the current study, the authors examined the impact of a decade of an alternative, 3-year cotesting, on rates of precancer and cancer at Kaiser Permanente Northern California. The effect on screening efficiency, defined as numbers of cotests/colposcopy visits needed to detect a precancer, also was considered.
  
  
  METHODS
  Two cohorts were defined. The "open cohort" included all women screened at least once during the study period; > 1 million cotests were performed. In a fixed "long-term screening cohort," the authors considered the cumulative impact of repeated screening at 3-year intervals by restricting the cohort to women first cotested in 2003 through 2004 (ie, no women entering screening later were added to this group).
  
  
  RESULTS
  Detection of cervical intraepithelial neoplasia 3/adenocarcinoma in situ (CIN3/AIS) increased in the open cohort (2004-2006: 82.0/100,000 women screened; 2007-2009: 140.6/100,000 women screened; and 2010-2012: 126.0/100,000 women screened); cancer diagnoses were unchanged. In the long-term screening cohort, the detection of CIN3/AIS increased and then decreased to the original level (2004-2006: 80.5/100,000 women screened; 2007-2009: 118.6/100,000 women screened; and 2010-2012: 84.9./100,000 women screened). The number of cancer diagnoses was found to decrease. When viewed in terms of screening efficiency, the number of colposcopies performed to detect a single case of CIN3/AIS increased in the cohort with repeat screening.
  
  
  CONCLUSIONS
  Repeated cotesting at a 3-year interval eventually lowers population rates of precancer and cancer. However, a greater number of colposcopies are required to detect a single precancer. Cancer 2016;122:3682-6. © 2016 American Cancer Society.
authors.affiliation: Clinical Genetics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland.
authors.forename: Michelle I
authors.identifier: http://orcid.org/0000-0002-4080-7242
authors.initials: MI
authors.lastname: Silver
authors.affiliation: Clinical Genetics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland.
authors.forename: Mark
authors.initials: M
authors.lastname: Schiffman
authors.affiliation: Regional Laboratory, Kaiser Permanente Northern California, Berkeley, California.
authors.forename: Barbara
authors.initials: B
authors.lastname: Fetterman
authors.affiliation: Regional Laboratory, Kaiser Permanente Northern California, Berkeley, California.
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Poitras
authors.affiliation: Clinical Genetics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland.
authors.forename: Julia C
authors.initials: JC
authors.lastname: Gage
authors.affiliation: Clinical Genetics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Wentzensen
authors.affiliation: Regional Laboratory, Kaiser Permanente Northern California, Berkeley, California.
authors.forename: Thomas
authors.initials: T
authors.lastname: Lorey
authors.affiliation: Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, New York.
authors.forename: Walter K
authors.initials: WK
authors.lastname: Kinney
authors.affiliation: Division of Gynecologic Oncology, Kaiser Permanente Medical Care Program, Oakland, California.
authors.forename: Philip E
authors.initials: PE
authors.lastname: Castle
mesh_terms: D000328:Adult; D002140:California; D003127:Colposcopy / Q000379:methods; D005260:Female; D006801:Humans; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D065006:Papanicolaou Test / Q000379:methods; D027383:Papillomaviridae / Q000302:isolation & purification; D030361:Papillomavirus Infections / Q000150:complications* / Q000821:virology; D011230:Precancerous Conditions / Q000175:diagnosis / Q000209:etiology* / Q000473:pathology / Q000821:virology*; D012307:Risk Factors; D040242:Risk Reduction Behavior; D002583:Uterine Cervical Neoplasms / Q000175:diagnosis / Q000209:etiology* / Q000473:pathology / Q000821:virology*; D014626:Vaginal Smears / Q000379:methods; D002578:Uterine Cervical Dysplasia / Q000175:diagnosis / Q000473:pathology / Q000821:virology
keywords: biopsy; cervical cancer; cervical intraepithelial neoplasia; colposcopy; cotest; human papillomavirus; screening