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 10 738 women who were eligible to participate, 10 049 (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.

Determinants of human papillomavirus 16 serological conversion and persistence in a population-based cohort of 10 000 women in Costa Rica

“…As previously described, study enrolment was conducted in 1993 -94 with approval from the NCI and local institutional review boards (Herrero et al, 1997;Hildesheim et al, 2001;Bratti et al, 2004). Briefly, the cohort was a representative sample of the adult female population in Guanacaste, Costa Rica in 1993 -94.…”

A case–control study of endogenous hormones and cervical cancer

“…The Guanacaste cohort has been described in detail (Herrero et al, 1997). The study was conducted after approval by the NCI and local institutional review boards, and all participants provided written informed consent.…”

Family history as a co‐factor for adenocarcinoma and squamous cell carcinoma of the uterine cervix: Results from two studies conducted in Costa Rica and the United States

“…12 As a starting point for our efforts to evaluate the role of genetic susceptibility in the development of cervical cancer, we sought to evaluate whether family history of cervical or other cancers is associated with cervical cancer of squamous or glandular origin. For this purpose, data from 2 large studies were evaluated: a casecontrol study of squamous cervical cancers and its precursors nested within a population-based cohort of 10,000 women in Costa Rica, 13 and a multicenter case-control study of in situ and invasive squamous and adenocarcinomas conducted in the United States.…”