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BACKGROUND: Worldwide, breast cancer is the most common cancer and is the leading cause of cancer death among women. METHODS: To describe global trends, we compared age-adjusted incidence and mortality rates over three decades (from 1973-77 to 1993-97) and across several continents. RESULTS: Both breast cancer incidence and mortality rates varied 4-fold by geographic location between countries with the highest and lowest rates. Recent (1993-1997) incidence rates ranged from 27/100,000 in Asian countries to 97/100,000 among US white women. Overall, North American and northern European countries had the highest incidence rates of breast cancer; intermediate levels were reported in Western Europe, Oceania, Scandinavia, and Israel; and Eastern Europe, South and Latin America, and Asia had the lowest levels. Breast cancer incidence rose 30-40% from the 1970s to the 1990s in most countries, with the most marked increases among women aged > or =50 years. Mortality from breast cancer paralleled incidence: it was highest in the countries with the highest incidence rates (between 17/100,000 and 27/100,000), lowest in Latin America and Asia (7-14/100,000), and rose most rapidly in countries with the lowest rates. CONCLUSIONS: Breast cancer incidence and mortality rates remain highest in developed countries compared with developing countries, as a result of differential use of screening mammograms and disparities in lifestyle and hereditary factors. Future studies assessing the combined contributions of both environmental and hereditary factors may provide explanations for worldwide differences in incidence and mortality rates.

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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.

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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

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Los problemas que plantean los estudios epidemiológicos sobre cáncer en los países en desarrollo con frecuencia son de carácter único. En este artículo se relata la experiencia de los autores al llevar a cabo un estudio de casos y testigos sobre carcinoma invasor de cuello uterino en cuatro países latinoamericanos (Colombia, Costa Rica, México, y Panamá). El estudio incluyo, la realización de entrevistas y la obtención de muestras biológicas de 759 pacientes con carcinoma invasor de cuello uterino, 1 467 mujeres que sirvieron como testigos apareados y 689 compañeros sexuales de las mujeres monógamas incluidas en el estudio. Se describen en términos generales la planificación y los métodos usados en la selección, en la realización de encuestas y en la obtención de datos completos, en lo posible exentos de sesgos. También se señalan algunas de las principales ventajas y desventajas de la investigación epidemiológica en zonas en desarrollo similares a las de este estudio

Disponible en inglés en Bull PAHO 25(1), 1991

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The challenges involved in conducting epidemiologic studies of cancer in developing countries can be and often are unique. This article reports on our experience in performing a case-control study of invasive cervical cancer in four Latin American countries (Colombia, Panama, Mexico, and Costa Rica), the summary medical results of which have been published in a previous issue of this journal. The study involved a number of principal activities- mainly selecting, conducting interviews with, and obtaining appropriate biologic specimenes from 759 cervical cancer patients, 1,467 matched female controls, and 689 male sex partners of monogamous female subjects. This presentation provides an overview of the planning and methods used to select the subjects, conduct the survey work, and obtain complete and effectively unbiased data. It also points out some of the important advantages and disadvantages of working in developing areas similar to those serving as locales for this study

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Risk factor for invasive carcinoma of the uterine cervix in Latin America

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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

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In Medellin, Colombia, a study was conducted on the relationship between smoking and the incidence of cancer. Data were also collected on the consumptiion 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

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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

This article was also published in spanish in the Bol. Oficina Sanit. Panam Vol. 114, No. 1, 1993

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