Desing and methods of a population-based natural history study of cervical neoplasia in a rural province of Costa Rica: the Guanacaste Project / Diseño y métodos usados en un estudio poblacional sobre la historia natural de las neoplasias de cuello uterino en una provincia rural de Costa Rica: el Proyecto de Guanacaste

En el presente trabajo se describe la fase de reclutamiento de un estudio poblacional sobre la historia natural de las neoplasias de cuello uterino en Guanacaste, provincia rural costarricense donde las tasas de cáncer cervicouterino invasor son invariablemente altas. Las metas principales del estudio son investigar el papel que desempeñan la infección por el virus del papiloma humano (VPH) y sus cofactores en la etiología de las neoplasias cervicouterinas de alto grado, y evaluar las nuevas tecnologías empleadas en el tamizaje del cáncer cervical. Para empezar se seleccionó una muestra aleatoria de segmentos censuales y, con la ayuda de trabajadores de acción comunitaria del Ministerio de Salud de Costa Rica, se hizo un recuento de todas las habitantes de 18 años de edad o mayores. De las 10 738 mujeres que cumplían con los requisitos para participar, 10 049 (93,6%) fueron entrevistadas después de haber dado su consentimiento informado por escrito. Después de la entrevista sobre los factores de riesgo del cáncer cervicouterino, se hizo un examen pélvico a las mujeres que dijeron haber tenido actividad sexual. El examen pélvico incluyó la determinación del pH vaginal y la obtención de células para análisis citológico mediante tres técnicas distintas. También se obtuvieron células cervicales para determinar la presencia y cantidad de ADN de 16 tipos de VPH diferentes y se tomaron dos fotografías del cérvix que fueron interpretadas en un local distinto por un experto en colposcopia. Por último, se sacaron muestras de sangre para hacer ensayos inmunológicos y determinaciones de micronutrientes. Las mujeres con un diagnóstico citológico anormal o un cervigrama positivo, más una muestra del grupo en general, fueron remitidas para hacerles colposcopia y se tomaron biopsias cuando se observaron lesiones. El tamizaje con fines de reclutamiento servirá de base para un estudio de prevalencia de casos y controles, y las integrantes de la cohorte sin enfermedad avanzada tendrán un seguimiento activo a intervalos mínimos de un año, con el propósito de estudiar la historia natural de la infección por VPH y los orígenes de las lesiones escamosas intraepiteliales de alto grado. Se describe en detalle la operación de campo y se hace especial alusión a la realización de estudios de este tipo en países en desarrollo. También se presentan datos descriptivos sobre la prevalencia de la enfermedad y la exposición a diversos factores de riesgo

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 the geographic variation of invasive cervical cancer in Costa Rica

The incidence of cervical cancer in Costa Rica is about twice as high in the coastal regions as in the interior. To study these regional variation, we used data from a 1986-1987 case-control study of 192 Costa Rican women with invasive cervical cancer and 372 controls. Risk factors identified included the following: The study participant's (1) number of sexual partner, (2) age at first sexual intercourse, (3) number of live births, (4) presence of type 16/18 human papillomavirus (HPV) DNA, (5) venereal disease (VD) history, (6) Pap smear history, and (7) socioeconomic status. The adjusted relative risk (RR) and 95 percent confidence intervals (CI) for each of these risk factors were as follows: (1) -4 vs. 1 sexual partner: RR = 2.0,95 percent CI = 1.1-3.5; (2) age of initiation -15 vs. 18 years: RR = 1.5, 95 percent CI = 0.9-2.5; (3) -6 vs. -1 live birth: RR = 1.7, 95 percent CI = 0.7-3.9; (4) HPV 16/18 DNA in cervix: RR = 2.8, 95 percent CI = 1.9-4.2; (5) VD history: RR = 2.2, 95 percent CI 1.2-4.0; (6) no Pap smear; RR = 2.4 95 percent CI = 1.5-3.8; and (7) low socioeconomic status: RR = 2.0, 95 percent CI = 1.2-3.2. The population-attibutable risk related to HPV detection, four or more sexual partners, six or more live births, no prior Pap smear, and low socioeconomic status were 39 percent, 38 percent, 29 percent, and 22 percent, respectively

Relacion del tabaquismo con canceres de vias respiratorias, digestivas y urinarias: Estudio de casos y testigos / Relationship between smoking and cancers of respiratory, digestive, and urinary tract: A case control study

In Medellin, Colombia, a study was conducted on the relationship between smoking and the incidence of cancer. Data were also collected on the consumption of alcohol and coffee. Cases of cancer of the bladder, larynx, oral/hypopharyngeal cavity, and the lung were included, and controls were matched with the patients on the basis of sex, age, and socioeconomic status. Most of the tobacco smoked by the population studied was black tobacco. Verification of a strong correlation between the consumption of tobacco and cancer of these four sites confirms that smoking is a serious added health risk in the developing countries. It was confirmed that the habitual consumption of alcoholic beverages, especially those with a high alcohol content such as aquavite, increases the risk of developing cancers of the bladder, larynx, and oral/hypopharyngeal cavity. A correlation was observed between the consumption of coffe and cancers of the larynx and oral/hypopharyngeal cavity- an apparently new result that deserves to be investigated in greater depth. Research of this type is needed in the developing countries in order to have the information on which to base the adoption of anti-smoking measures