title: Urbanization and the incidence of abnormalities of squamous and glandular epithelium of the cervix.
abstract: BACKGROUND
  The large data bases of the Dutch cervical screening program can be exploited to establish the relation between urbanization and the incidence of abnormalities of the squamous and glandular epithelium, including mild or greater changes of the squamous and glandular epithelium of the cervix.
  
  
  METHODS
  Six cytology laboratories in the context of the Dutch cervical screening program screened over 190,000 cervical smears. Urbanization (place of residence) data were derived from postal codes. All smears were coded with the Dutch national coding system, the Dutch national classification system KOPAC, in which squamous abnormalities are coded S4-S9, and glandular cell changes are coded G4-G9. From the scores per 1000 screened women, the relative risk (RR) of living in a large city compared with living in rural areas was calculated. To investigate a trend in incidence in relation to urbanization, the Schaafsma method was used.
  
  
  RESULTS
  Of the smears with positive cytology, mild squamous dysplasia (S4) had the highest incidence per 1000 screened women (4.32), and the lowest incidence was found for adenocarcinoma (in situ; G7/G9; RR, 0.07). The RR for urban women ranged from 1.73 for moderate squamous dysplasia (S5) to 7.55 for adenocarcinoma (in situ; G7/G9). For smears with positive cytology for both squamous and glandular abnormalities, the Schaafsma method indicated a significant positive trend.
  
  
  CONCLUSIONS
  The incidence of squamous and glandular abnormalities are maximal in women who live in a large city, which, in The Netherlands, is where there also is a population at high risk for human papillomavirus and bacterial vaginosis.
authors.affiliation: Leiden Cytology and Pathology Laboratory, Leiden, The Netherlands. m.e.boon@lcpl.nl
authors.forename: Mathilde E
authors.initials: ME
authors.lastname: Boon
authors.forename: Hedda H
authors.initials: HH
authors.lastname: van Ravenswaay Claasen
authors.forename: Roelof P
authors.initials: RP
authors.lastname: van Westering
authors.forename: Lambrecht P
authors.initials: LP
authors.lastname: Kok
mesh_terms: D000230:Adenocarcinoma / Q000453:epidemiology*; D000328:Adult; D002278:Carcinoma in Situ / Q000453:epidemiology*; D016021:Epidemiologic Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008403:Mass Screening; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D027383:Papillomaviridae; D030361:Papillomavirus Infections / Q000150:complications; D012307:Risk Factors; D014412:Tumor Virus Infections / Q000150:complications; D014505:Urban Population; D002578:Uterine Cervical Dysplasia / Q000453:epidemiology*; D002583:Uterine Cervical Neoplasms / Q000453:epidemiology*; D014626:Vaginal Smears