title: Design and methods of a population-based natural history study of cervical neoplasia in a rural province of Costa Rica: the Guanacaste Project.
abstract: This paper reports on the enrollment phase of a population-based natural history study of cervical neoplasia in Guanacaste, a rural province of Costa Rica with consistently high rates of invasive cervical cancer. The main goals of the study are to investigate the role of human papillomavirus (HPV) infection and its co-factors in the etiology of high-grade cervical neoplasia, and to evaluate new cervical cancer screening technologies. To begin, a random sample of censal segments was selected and enumeration of all resident women 18 years of age and over was conducted with the aid of outreach workers of the Costa Rican Ministry of Health. Of the 10738 women who were eligible to participate, 10049 (93.6%) were interviewed after giving written informed consent. After the interview on cervical cancer risk factors was administered, a pelvic examination was performed on those women who reported previous sexual activity. The pelvic examination included a vaginal pH determination and collection of cervical cells for cytologic diagnosis using three different techniques. Additional cervical cells were collected for determination of the presence and amount of DNA from 16 different types of HPV, and two photographic images of the cervix were taken and interpreted offsite by an expert colposcopist. Finally, blood samples were collected for immunologic and micronutrient assays. Women with any abnormal cytologic diagnosis or a positive Cervigram, as well as a sample of the whole group, were referred for colposcopy, and biopsies were taken when lesions were observed. The enrollment screening will serve as the basis for a prevalent case-control study, and the members of the cohort free from serious disease will be followed actively, at intervals of no more than a year, to study the natural history of HPV infection and the origins of high-grade squamous intraepithelial lesions (HSIL). Details of the field operation are outlined, with particular reference to the realization of this kind of study in developing countries. Descriptive data on the prevalence of disease and exposure to various risk factors are also presented.
authors.affiliation: International Agency for Research on Cancer, Lyon, France.
authors.forename: R
authors.initials: R
authors.lastname: Herrero
authors.forename: M H
authors.initials: MH
authors.lastname: Schiffman
authors.forename: C
authors.initials: C
authors.lastname: Bratti
authors.forename: A
authors.initials: A
authors.lastname: Hildesheim
authors.forename: I
authors.initials: I
authors.lastname: Balmaceda
authors.forename: M E
authors.initials: ME
authors.lastname: Sherman
authors.forename: M
authors.initials: M
authors.lastname: Greenberg
authors.forename: F
authors.initials: F
authors.lastname: Cárdenas
authors.forename: V
authors.initials: V
authors.lastname: Gómez
authors.forename: K
authors.initials: K
authors.lastname: Helgesen
authors.forename: J
authors.initials: J
authors.lastname: Morales
authors.forename: M
authors.initials: M
authors.lastname: Hutchinson
authors.forename: L
authors.initials: L
authors.lastname: Mango
authors.forename: M
authors.initials: M
authors.lastname: Alfaro
authors.forename: N W
authors.initials: NW
authors.lastname: Potischman
authors.forename: S
authors.initials: S
authors.lastname: Wacholder
authors.forename: C
authors.initials: C
authors.lastname: Swanson
authors.forename: L A
authors.initials: LA
authors.lastname: Brinton
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002278:Carcinoma in Situ / Q000097:blood / Q000453:epidemiology* / Q000209:etiology; D002294:Carcinoma, Squamous Cell / Q000097:blood / Q000453:epidemiology* / Q000209:etiology; D015331:Cohort Studies; D003127:Colposcopy; D015897:Comorbidity; D003364:Costa Rica / Q000453:epidemiology; D004279:DNA, Viral / Q000032:analysis; D004032:Diet; D004812:Epidemiologic Methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D027383:Papillomaviridae / Q000302:isolation & purification / Q000472:pathogenicity*; D030361:Papillomavirus Infections / Q000150:complications / Q000453:epidemiology*; D015995:Prevalence; D017584:Reproductive History; D012307:Risk Factors; D012424:Rural Population; D012907:Smoking / Q000453:epidemiology; D012959:Socioeconomic Factors; D014412:Tumor Virus Infections / Q000150:complications / Q000453:epidemiology*; D002577:Uterine Cervical Diseases / Q000097:blood / Q000453:epidemiology; D002583:Uterine Cervical Neoplasms / Q000097:blood / Q000453:epidemiology* / Q000209:etiology; D014626:Vaginal Smears; D002578:Uterine Cervical Dysplasia / Q000097:blood / Q000453:epidemiology* / Q000209:etiology
chemical_list: D004279:DNA, Viral