A prospective study of diet, lifestyle, and genetic factors and the risk of cancer in Khon Kaen Province, northeast Thailand: description of the cohort.

Cohort studies are the preferred design in observational epidemiology, but few involving the general population have been performed in Asia, and most concern affluent urban populations.The Khon Kaen study has recruited about 25,000 subjects, aged mainly 35-64, from villages in the relatively underdeveloped north-east of Thailand. All subjects underwent simple physical examination, completed an interviewer-administered questionnaire (including sections on lifestyle, habits, and diet) and donated specimens of blood, which were processed and stored in a biological bank at -20 degrees C. Female subjects (about 16,500) were offered screening by Pap smear, and specimens of cells from the cervix were stored at -20 degrees C. This paper describes the methodology of the study, and the characteristics of the participants. Almost all subjects are peasant farmers, with low annual income and body mass, although 14.6% of women had a BMI in the obese range (>30 kg/m(2)). Smoking was common among men (78% regular smokers, most of whom used home-produced cigarettes), but rare among women. Fertility levels were relatively high, with a more than half the women having four or more live births. 23.4% of subjects were infected with the liver fluke Opisthorchis viverrini, known to be highly endemic in this region. Follow-up of the cohort is by record-linkage to the provincial cancer registry. By 2003, 762 cancer cases had occurred, the most common being cancers of the liver (363 cases) and cervix uteri (44 cases). The antecedents of these cancers are being investigated using a nested case-control approach. The cohort will yield increasing numbers of cancers for study in the next decade, giving important information on the relative importance of dietary and lifestyle factors in a rural population, undergoing gradual transition to a more westernised lifestyle.

Consistency of cytology diagnosis for cervical cancer between two laboratories.

The principal approach to the prevention of cancer of the cervix uteri has been through screening programmes, using the cervical smear (Pap test) to detect precursor lesions. The sensitivity and specificity of Pap smears depend on the skill of the observer in recognizing and classifying a variety of cellular abnormalities. We have studied the reproducibility of cytological diagnosis, according the Bethesda classification, made by cytologists in Khon Kaen, north-east Thailand, and in Helsinki, Finland, on smears taken from rural women undergoing screening during 1994-2001. A total of 313 slides were reviewed. The prevalence of abnormalities was relatively high, since the series included smears judged abnormal in Khon Kaen or from women who developed cancer during follow-up, as well as a group whose smears were negative. In general, the reviewing cytologist in Finland evaluated more slides as abnormal than in the initial report. The level of agreement between the two observers was evaluated by calculating the coefficient of concordance (Kappa). The kappa score depended upon the degree of detail in the diagnosis; it was 0.43 for the presence or not of an epithelial abnormality (the General Categorization of the Bethesda system), and rather higher (0.5) for separating low grade from high grade (HSIL or worse) abnormalities or glandular lesions. Agreement was only fair (0.37) when the more detailed Bethesda categories (seven) were used. The reproducibility of cervical cytology evaluations is critical to the success of screening programmes, and in this programme in a moderate-high risk population of women in rural Thailand, we found that agreement between skilled observers, at the level of tests requiring diagnostic follow-up or not, was only moderate. The women in this study are being traced to evaluate the true sensitivity of screening in terms of the lesions found on histology, during a prolonged follow up of 4 or more years.

Early detection of cervical cancer with visual inspection methods: a summary of completed and on-going studies in India

La India es un país de alto riesgo de cáncer cervical, donde se presentan cerca de la cuarta parte de los casos del total mundial (126 000 casos incidentes y 71 000 muertes durante 2000). La tasa de incidencia estandarizada por edad se encuentra en el rango de 16 a 55 por 100 000 mujeres en diferentes regiones con tasas particularmente altas en áreas rurales. El control del cáncer cervical por detección temprana y tratamiento es una prioridad del Programa Nacional de Control de Cáncer y, desafortunadamente, no hay programas organizados de tamizaje citológico en este país. La infraestructura técnica y financiera para organizar tamizaje en este tipo de cáncer, ha promovido la inspección visual como una potencial alternativa de la citología cervical en la India. Se investigan cuatro tipos de opciones de detección visual de neoplasia cervical: a) inspección a ojo desnudo sin la aplicación de ácido acético, opción ampliamente conocida como downstaging; b) inspección de ojo desnudo después de la aplicación de ácido acético de 3 a 5 por ciento (VIA); c) VIA usando un dispositivo de aumento (VIAM); d) inspección visual después de la aplicación de yodo-lugol (VILI). Se ha mostrado que el Downstaging ha sido pobremente sensible y específico para detectar neoplasia cervical y no es considerado ampliamente como una prueba de tamizaje conveniente para cáncer cervical. VIA, VIAM y VILI son frecuentemente investigados en estudios de corte transversal multicéntricos (sin verificación de sesgo), en los que se evalúan simultáneamente la citología y las pruebas del VPH; los resultados de esas investigaciones estarán disponibles próximamente. Estos estudios proveerán información valiosa sobre el desarrollo de pruebas comparativas para detectar lesiones de alto grado precursoras de neoplasia cervical, y cáncer invasor. Los resultados de los análisis de los datos de dos estudios previos indicaron una sensibilidad aproximada de 93.4 por ciento y una especificidad de 85.1 por ciento para VIA en la detección de CIN 2-3 o lesiones invasoras, comparadas con las de citología con 72.1 por ciento y 91.6 por ciento de sensibilidad y especificidad, respectivamente. La eficacia de VIA para la reducción de la incidencia y la mortalidad de cáncer cervical y su costo-efectividad están siendo actualmente investigadas en dos ensayos de intervención aleatorizados controlados en población de la India. Uno de esos estudios es un ensayo con cuatro brazos que establece la eficacia...

Trends in Cancer Incidence in Kyadondo County; Uganda; 1960-1997

Incidence rates of different cancers have been calculated for the population of Kyadondo county (Kampala; Uganda) for four time periods (1960-1966; 1967-1971; 1991-1994; 1995-1997); spanning 38 years in total. The period coincides with marked social and lifestyle changes and with the emergence of the AIDS epidemic. Most cancers have increased in incidence over time; the only exceptions being cancers of the bladder and penis. Apart from these; the most common cancers in the early years were cervix; oesophagus and liver; all three have remained common; with the first two showing quite marked increases in incidence; as have cancers of the breast and prostate. These changes have been overshadowed by the dramatic effects of the AIDS epidemic; with Kaposi's sarcoma emerging as the most common cancer in both sexes in the 1990s; and a large increase in incidence of squamous cell cancers of the conjunctiva. In the most recent period; there also seems to have been an increase in the incidence of non-Hodgkin lymphomas. So far; lung cancer remains rare. Cancer control challenge. With little improvement in the incidence of cancers associated with infection and poverty (liver; cervix; oesophagus); it must face the burden of AIDS-associated cancers; while coping with the emergence of cancers associated with Weternization of lifestyles (large bowel; breast and prostate)

AIDS-related Cancers in Africa: maturation of the epidemic in Uganda

The AIDS epidemic has passed its peak in Uganda; with possible consequences for the risk of cancers related to infectious agents. Objective: To compare the incidence of cancers linked to infections with HIV; before the AIDS epidemic (the 1960s); at its high point (the early 1990s) when HIV - seroprevalence and AIDS notifications peaked; and after the onset of its decline in the later 1990s. Methods: Analysis of incidence rates of infection-associated cancers in the population of Kyadondo county; in 1960-1971; 1991-1994; and 1995-1997. Comparison with data on prevalence of HIV infection; and notifications of AIDS. Results: The incidence of Kaposi's sarcoma has increased enormously since the 1960s; with a shift to earlier age at onset; and more generalised and nodal disease; there has been little change in the profile during the 1990s. There was a large increase in incidence of squamous cell carcinomas of the conjunctiva; which has continued through the 1990s. Non-Hodgkin's lymphomas showed little increase in incidence until the most recent period; in which the incidence has increased both in children (particularly Burkitt's lymphomas) and adults. Although the incidence of cervical cancer was higher in the 1990s than the 1960s; it seems doubtful that this is related to HIV infection. Certain other cancers which have been linked to AIDS in western populations (Hodgkin's disease; anal carcinoma; childhood leiomyosarcoma) show no changes in risk. Conclusion: The AIDS epidemic has dramatically changed the profile of cancer in Uganda. Trends in the AIDS-related cancers are consistent with current knowledge concerning the mechanisms behind the increased risk. The incidence of certain cancers with a viral aetiology (liver; cervix; penis; Hodgkin's disease) appears not to have been influenced by AIDS