Examinando por Autor "Irwin, Kathleen L."
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Ítem Cervical cancer risk and use of depot-medroxyprogesterone acetate in Costa Rica(International Journal of Epidemiology., Volumen 17, no. 4, 1988) Oberle, Mark W.; Irwin, Kathleen L.; Rosero-Bixby, Luis; Fortney, Judith A.; Lee, Nancy C.; Whatley, Annes S.; Bonhomme, Michele G.The long-term safety of the injectable contraceptive, depot medroxyprogesterone acetate (DMPA), has been the subject of intense debate, chiefly because of reports of breast and endometrial neoplasia in animal studies. Most epidemiological studies of DMPA use and cancer have been hindered by small sample size and short periods of potential latency.1-3 A recent, large case-control study by the World Health Organization (WHO) did not identify any overall increased risk of invasive cervical cancer among DMPA users.4-5 However, women who had used DMPA for five years or more had an elevated risk of invasive cervical cancer, compared to never users (odds ratio = 2.2, 95% confidence interval, 1.2 - 4.2). This increased risk was confined to long-term users who were under 46 years of age at diagnosis or who began using DMPA before 30 years of age. The WHO study did not include cases of carcinoma in situ (CIS). Costa Rica offers an opportunity to examine the relationship between DMPA use and cervical cancer, bfccause of its high incidence of cervical cancer and the popularity of DMPA after its introduction in the early 1970s. In 1983, cervical cancer was the most commonly reported cancer and the second leading cause of cancer mortality among Costa Rican women.6 The reported incidence of invasive cervical cancer in 1983 was 36.2/100 000 women, one of the highest rates in the world.6 DMPA has been a popular contraceptive in Costa Rica; approximately 11 % of currently married women, 15-49 years of age have used an injectable contraceptive, chiefly DMPA.7 However, since 1983, DMPA has not been approved for contraceptive use in Costa Rica. To further address the long-term safety of DMPA, the Costa Rican Demographic Association conducted a population-based, case-control study of cervical and breast cancer in Costa Rica in 1984-85. We report here our analysis of the association between DMPA use and cervical cancer. The breast cancer cases are the subject of a separate report.8Ítem Estudios de detección selectiva del cáncer de cérvix y del cáncer de mama en Costa Rica(Bol Of Sanit Panam, Vol. 109, no. 3, 1990) Irwin, Kathleen L.; Oberle, Mark W.; Rosero-Bixby, LuisEl cáncer de cuello uterino (cáncer de cérvix) y el cáncer de mama son las principales causas de morbilidad y mortalidad femenina por cáncer en Costa Rica. Se evaluaron los métodos de detección de estos dos tipos de cáncer en las mujeres costarricenses de 25 a 58 años a partir de los datos de una encuesta nacional realizada en 1984 y 1985. El frotis de cuello uterino (frotis cervical) es un método muy utilizado para detectar el cáncer de cérvix, y 83,5% de las mujeres señalaron que se habían hecho por lo menos un frotis. Sin embargo, más de un tercio no se habían hecho el primer frotis o la primera exploración ginecológica hasta los 30 años, mucho después de la edad media de la primera relación sexual. Las pruebas de detección fueron menos comunes en grupos de mujeres de alto riesgo de cáncer de cérvix, incluidas las que tenían múltiples compañeros sexuales y las que habían tenido varios hijos. Un análisis de casos y testigos reveló que él riesgo de cáncer invasor en las mujeres que se habían hecho un frotis cervical era alrededor de la mitad del riesgo correspondiente en las mujeres que no se habían hecho ningún frotis. Menos de la mitad de las mujeres señalaron que se habían hecho explorar las mamas por un profesional o que habían practicado la autoexploración mamaria. Las mujeres mayores de 50 años, que por su edad se encuentran en el grupo más expuesto al cáncer de mama, eran las que con menor frecuencia se habían sometido a ambos tipos de exploración. Se podría aumentar la frecuencia de las pruebas de detección de los cánceres de cérvix y de mama prestando especial atención, por medio del sistema de servicios de salud existente, a las mujeres de los grupos de alto riesgo que no se hayan sometido a suficientes exploraciones.Ítem Oral contraceptives and cervical cancer risk in Costa Rica(Journal of the American Medical Association, Vol. 259, no. 1, 1988) Irwin, Kathleen L.; Rosero-Bixby, Luis; Oberle, Mark W.; Lee, Nancy C.To examine the relationship between cervical cancer and oral contraceptive (OC) use, we analyzed data from a population-based, case-control study in Costa Rica. Women aged 25 to 58 years in whom cervical cancer was diagnosed and reported to the National Tumor Registry were examined as two separate case groups: invasive cervical cancer and carcinoma in situ (CIS). Controls were women aged 25 to 58 years identified through a national survey. Women who had used OCs had no increased risk of invasive cervical cancer compared with women who had never-used OCs (relative risk, 0.8; 95% confidence interval, 0.5 to 1.3). Women who had used OCs had an increased risk of CIS compared with those who had never used OCs (relative risk, 1.6; 95% confidence interval, 1.2 to 2.2). However, further analyses indicated that this increased risk was confined to those who had recently used OCs. Also, the risk of CIS was not elevated in subgroups in which a history of cervical smears was not strongly linked to OC use. The elevated risk of CIS among OC users may therefore reflect a bias caused by enhanced detection of disease rather than a causal association.Ítem Screening practices for cervical and breast cáncer in Costa Rica(Bull Pan Am Health Organ. v. 25, n.1,, 1991) Irwin, Kathleen L.; Oberle, Mark W.; Rosero Bixby, LuisCervical cancer and breast cancer are leading causes of cancer-related morbidity and mortality in Costa Rica. This article reports results of an evaluation of cervical and breast cancer screening practices among Costa Rican women 25 to 58 years old that was based on a nationwide 1984-1985 survey. The evaluation showed that while Pap smears were widely used to screen for cervical cancer, many women did not have their first cervical smear or gynecologic examination until age 30, and that cervical cancer screening was less common among certain high-risk groups, including women with multiple sexual partners and those with high parity. Less than half the women surveyed reported having had a breast examination by a health care provider. Utilization of both cervical cancer and breast cancer screening examinations could be increased by targeting inadequately screened high-risk women through the existing health care system.Ítem The effect of using different reference dates for control exposure measurement on relative risk estimates in a case-control study(Journal Clinical Epidemiologycal, Vol. 46, no. 5, 1993) Rampey, Alvin H.; Irwin, Kathleen L.; Oberle, Mark W.; Kinchen, Steven; Lee, Nancy C.; Marsden, Anne; Rosero Bixby, LuisArtículo científico -- Universidad de Costa Rica, Instituto de Investigaciones en Saud. 1993. Debido a las políticas de la revista en la que el artículo fue publicado, no es posible distribuir la edición del editor/PDF. In case-control studies in which case and control enrollment periods are not identical, exposure status for time-dependent variables is often measured relative to a reference date. Using data from a case-control study of the relation between cervical cancer and oral contraceptive (OC) use in which control enrollment began 6 months after the end of case enrollment, we evaluated the effect on odds ratios from using five different reference dates to determine the controls' exposure status. The choice of reference date had little effect on the odds ratios in this study. Reference dates for time-dependent exposure variables should be considered carefully in studies when case and control enrollment periods are not identical.