RESUMO
A case-control study to evaluate risk factors for gastric cancer was carried out among 292 cases of gastric cancer and 485 controls in a high-risk area of Venezuela. Subjects were interviewed using a structured questionnaire, which elicited information on residential history, socio-economic status, family history of gastric diseases, smoking, drinking and dietary habits. Habitual diet was estimated from a meal-structured food frequency questionnaire on 75 food items. There was a strong inverse association with social class, as measured by education and by indicators of poverty. The results of the dietary analysis suggest that a diet high in starch and low in meat, fish and fresh vegetables increases risk of gastric cancer. A protective effect was observed for frequent consumption of allium vegetables. Inverse associations were found with height, which may reflect nutritional status in childhood, and with refrigerator use in the first two decades of life. Alcohol and tobacco consumption was investigated among males only, since the prevalence of alcohol and tobacco use was very low in females. Alcohol drinkers were at higher risk than non-drinkers and there was a small excess risk for current smokers compared with never smokers. There was some evidence of familial aggregation of gastric cancer. These findings will have important implications in planning preventive strategies for gastric cancer in Venezuela.
Assuntos
Consumo de Bebidas Alcoólicas/efeitos adversos , Neoplasias Gástricas/epidemiologia , Adulto , Estudos de Casos e Controles , Inquéritos sobre Dietas , Feminino , Humanos , Modelos Logísticos , Masculino , Análise Multivariada , Fatores de Risco , Fumar/efeitos adversos , Fatores Socioeconômicos , Neoplasias Gástricas/etiologia , Venezuela/epidemiologiaRESUMO
In this chapter we first describe the variation of cervical cancer in relation to social class. Thereafter we examine the causes for the occurrence of socioeconomic differences in invasive cervical cancer, using data from two case-control studies carried out in Colombia and Spain. Cervical cancer is the most common cancer in developing countries and the sixth most common in developed countries. In all areas, it is more frequent among women of low socioeconomic status, it is associated with multiple sexual partners and early age at first sexual intercourse, and both incidence and mortality are reduced by screening. According to population-based surveys in industrialized countries, men of low socioeconomic status report fewer sexual partners than men of high socioeconomic status but there is no clear indication that the same is true of women of low socioeconomic status. In the case-control studies in Spain and Colombia, the human papillomavirus and all other sexually transmitted diseases were more prevalent among women in low socioeconomic strata. Number of sexual partners and particularly contacts with prostitutes were higher among husbands of women of low socioeconomic status. Other potential risk factors for the disease, such as smoking and oral contraceptive use, and also cervical cancer screening (Pap smears), were more common in women of high social strata. Women with no schooling had a threefold higher risk in Spain and a fivefold higher risk in Colombia of having cervical cancer compared with women who had achieved a higher educational level. After adjustment for sexual behaviour, HPV DNA status, history of Pap smears and husband's contact with prostitutes, this association was considerably reduced. These results are indicative that socioeconomic differences in the incidence of cervical cancer can be partly explained by differences in the prevalence of HPV DNA. Men's sexual behaviour and particularly contacts with prostitutes might be a major contributor to the higher prevalence of HPV DNA among the poor.
Assuntos
Comportamento Sexual , Classe Social , Neoplasias do Colo do Útero/epidemiologia , Adolescente , Adulto , Fatores Etários , Idoso , Estudos de Casos e Controles , Coito , Colômbia/epidemiologia , Países Desenvolvidos/estatística & dados numéricos , Países em Desenvolvimento/estatística & dados numéricos , Escolaridade , Feminino , Humanos , Incidência , Masculino , Programas de Rastreamento , Pessoa de Meia-Idade , Papillomaviridae , Infecções por Papillomavirus/epidemiologia , Pobreza , Fatores de Risco , Fatores Sexuais , Trabalho Sexual , Parceiros Sexuais , Doenças Virais Sexualmente Transmissíveis/epidemiologia , Espanha/epidemiologia , Cônjuges , Infecções Tumorais por Vírus/epidemiologia , Neoplasias do Colo do Útero/mortalidade , Neoplasias do Colo do Útero/prevenção & controleRESUMO
OBJECTIVES: This study examined the causes of socioeconomic differences in invasive cervical cancer in two countries that differ substantially in cervical cancer incidence and economic development. METHODS: Data were derived from two case-control studies carried out in Spain and Colombia; there were 373 case subjects, 387 control subjects, and 425 husbands interviewed with a structured questionnaire. Exfoliated cells were obtained from cervical or penile scrapes and tested for human papillomavirus (HPV) DNA. RESULTS: Relative to better educated women, women with low educational levels in both countries reported fewer Pap smears and had a higher prevalence of HPV DNA. The prevalence ratio of HPV DNA across educational strata was twofold in Spain and fourfold in Colombia. In both countries, husbands of poorly educated women reported higher use of prostitutes than husbands of better educated women. In Colombia, 30% of husbands of poorly educated women harbored HPV DNA, compared with 10% of husbands of better educated women. CONCLUSIONS: Socioeconomic differences in invasive cervical cancer could be partly explained by differences in the prevalence of HPV DNA and by a lower use of preventive care.
Assuntos
Fatores Socioeconômicos , Neoplasias do Colo do Útero/epidemiologia , Neoplasias do Colo do Útero/etiologia , Adulto , Estudos de Casos e Controles , Colômbia/epidemiologia , DNA Viral/isolamento & purificação , Feminino , Humanos , Pessoa de Meia-Idade , Razão de Chances , Papillomaviridae/genética , Prevalência , Fatores de Risco , Espanha/epidemiologia , Neoplasias do Colo do Útero/virologiaRESUMO
BACKGROUND AND OBJECTIVES: Strong epidemiologic evidence indicates that human papillomavirus (HPV) is the main etiologic factor of cervical cancer. A few cohort studies suggest that most HPV infections are transient in young women and that persistent HPV infections are more common in older women. Little is known about the determinants of persistent HPV infections. The present study was aimed at increasing our knowledge about these determinants. GOALS: To identify risk factors for genital HPV DNA detection among cytologically normal middle-aged women. STUDY DESIGN: Eight hundred ten women who participated as control subjects in three case-control studies on cervical cancer in Spain, Colombia, and Brazil were included in this study. After an interview, women underwent a gynecologic examination with collection of exfoliated cells for a Papanicolaou smear and HPV DNA detection. Human papilloma virus DNA was detected by polymerase chain reaction (PCR)-based hybridization techniques. RESULTS: The HPV positivity rate was 10.5% in the whole population, but was higher in the areas with high incidence of cervical cancer (17% in Brazil and 13% in Colombia) than in Spain (4.9%), which is a low-risk area for cervical cancer. Age was related to the prevalence of HPV DNA in Brazil, but not in Spain and Colombia. In univariate analyses in all three countries, the prevalence of HPV DNA was positively associated with the number of lifetime sexual partners and inversely associated with the levels of family income and with age at first sexual intercourse. There was four times increase in the odds ratio (OR) of HPV infection in women who had six or more lifetime sexual partners compared with those with one or less. The use of any kind of contraceptive tended to decrease the OR for HPV detection. Their ORs ranged from 0.44 (barrier methods) to 0.48 (oral contraceptives). In Spain and Colombia, antibodies against Chlamydia trachomatis were positively associated with the prevalence of HPV DNA. In a final multivariate model, the positive associations with lifetime number of sexual partners, socioeconomic status, and C. trachomatis persisted. CONCLUSIONS: These results support the sexual transmission of HPV and suggest that socioeconomic status and antibodies to C. trachomatis are independent predictors of HPV detection in middle-aged cytologically normal women.
Assuntos
Papillomaviridae , Infecções por Papillomavirus/epidemiologia , Infecções Tumorais por Vírus/epidemiologia , Adulto , Fatores Etários , Brasil/epidemiologia , Infecções por Chlamydia/complicações , Chlamydia trachomatis , Colômbia/epidemiologia , Feminino , Humanos , Pessoa de Meia-Idade , Análise Multivariada , Razão de Chances , Reação em Cadeia da Polimerase , Prevalência , História Reprodutiva , Fatores de Risco , Estudos Soroepidemiológicos , Comportamento Sexual , Fatores Socioeconômicos , Espanha/epidemiologiaRESUMO
BACKGROUND: Epidemiologic evidence has been inconclusive in linking men's sexual behavior and genital human papillomaviruses (HPVs) with cervical cancer risk in their sexual partners in areas with a high incidence of cervical cancer. PURPOSE: This study assesses the role of men's sexual behavior and the presence of penile HPV DNA on the risk of their wives' developing cervical neoplasia in an area in Colombia with a high incidence of cervical cancer. METHODS: A total of 210 husbands of women with cervical intraepithelial neoplasia grade III (n = 118) or invasive squamous cell carcinoma of the cervix (n = 92) and a total of 262 husbands of women recruited as control subjects (173 and 89, respectively) were interviewed. Questionnaires included detailed information on sexual behavior. Exfoliated cells were obtained from the glans penis and from the distal urethra of the penis. The specimens were analyzed for HPV DNA by use of a polymerase chain reaction-based assay that included a generic probe and 25 type-specific probes. Serum specimens were collected and analyzed for antibodies to Chlamydia trachomatis, Treponema pallidum, herpes simplex virus type II, and Neisseria gonorrhoeae. RESULTS: Limited education (adjusted odds ratio [OR] = 4.4; 95% confidence interval [CI] = 1.9-9.8; for no schooling versus secondary or higher education) and presence of antibodies to C. trachomatis (adjusted OR = 2.5; 95% CI = 1.5-4.4) in husbands were the only identified risk factors for cervical neoplasia in their wives. The prevalence of HPV DNA in the penis was 25.7% among husbands of case women and 18.9% among husbands of control women (adjusted OR = 1.2; 95% CI = 0.6-2.3). Neither the lifetime number of female sexual partners (adjusted OR = 1.0; 95% CI = 0.4-2.6; for > 50 partners versus one to five) nor the lifetime number of female prostitutes as sexual partners (adjusted OR = 1.2; 95% CI = 0.7-2.0; for > or = 21 prostitutes versus one to five) was associated with the risk of cervical cancer. CONCLUSIONS: Our results are compatible with the hypothesis that in the population of Cali, whose women are at high risk of developing cervical cancer, exposure to HPV among young men is a common occurrence and is mediated by contacts with large numbers of female sexual partners and prostitutes. These widespread sexual practices limit the power of case-control studies to detect significant associations between men's sexual behavior and the cervical cancer risk in their sexual partners. HPV DNA detection in the penis of adult men is a poor reflection of lifetime exposure or of etiologically relevant exposure to HPV. The role of C. trachomatis in cervical carcinogenesis deserves further investigation. IMPLICATIONS: Further research is needed to elucidate the male's role in cervical carcinogenesis in populations at high risk for cervical cancer. HPV DNA prevalence surveys and studies of the natural history of HPV in young men will be of great value.
Assuntos
DNA Viral/análise , Papillomaviridae/genética , Pênis/virologia , Comportamento Sexual , Neoplasias do Colo do Útero/virologia , Carcinoma de Células Escamosas/virologia , Estudos de Casos e Controles , Colômbia/epidemiologia , Feminino , Humanos , Incidência , Masculino , Análise Multivariada , Fatores de Risco , Neoplasias do Colo do Útero/epidemiologia , Displasia do Colo do Útero/virologiaRESUMO
This study evaluates the association of antibodies against HPV-16-derived peptides with cervical cancer and estimates the sensitivity and specificity of the serological assays in relation to HPV DNA detection in cervical cells by PCR. Study subjects were derived from 4 case-control studies carried out in Spain and Colombia. Sera from 544 cases of CIN III and invasive cancer and of 543 age-matched controls were tested for antibodies to 5 peptides derived from E2, E7 (3 partially overlapping frames of HPV 16 denoted E7/ 1, E7/2, E7/3) and L2 open reading frames of HPV 16. HPV DNA was detected using a L1-PCR based method. Among cancer controls, antibody response to E2 and E7/1, E7/2, E7/3 was higher in Colombia (22.5%,7.2%,11.7%,12.6% respectively) than in Spain (17.1 %, 4.7%, 5.9%, 5.9%). E7 antibodies were related to stage, particularly in CIN III vs. invasive stages and less markedly within invasive stages. Detection of antibodies to the E7/1 was associated to CIN III (OR = 1.8). The risk of invasive cervical cancer was increased among those with antibodies to E2 (OR = 2.2), to E7/1 (OR = 4.2), to E7/2 (OR = 4.3), and to E7/3 (OR = 2.5). Presence of antibodies to all the 3 E7 peptides increased the risk of CIN III (OR = 5.6) and that of invasive cancer (OR = 17.5). High levels of antibodies to E7/1 or E7/2 or E7/3 increased the risk of invasive cervical cancer (OR for high levels of antibodies vs. negatives to E7/1 OR = 22.6; E7/2 OR = 7.5, E7/3 OR = 3.4). In the present analysis, antibodies to L2 were not associated with either CIN III or cervical cancer. Serological markers of HPV 16 detected less than half of the HPV-16-DNA-positive cases. It is concluded that antibodies to E2 and particularly E7 antigens are strongly associated with cervical cancer. Antibodies to E7 seem to be a moderate marker of tumor burden.
Assuntos
Anticorpos Antivirais/imunologia , Carcinoma/imunologia , Papillomaviridae/imunologia , Displasia do Colo do Útero/imunologia , Neoplasias do Colo do Útero/imunologia , Adulto , Antígenos Virais/imunologia , Carcinoma/microbiologia , Carcinoma in Situ/imunologia , Carcinoma in Situ/microbiologia , Estudos de Casos e Controles , Colômbia , Feminino , Humanos , Espanha , Neoplasias do Colo do Útero/microbiologiaRESUMO
A randomized chemoprevention trial on precancerous lesions of the stomach is being conducted in Tachira State, Venezuela. The aims of the study are to evaluate the efficacy of vitamin supplementation in preventing the progression rate of precancerous lesions. Here we report on the pilot phase of the study in which two antioxidant preparations were evaluated on their ability to raise antioxidant levels in plasma and in gastric juice. The study aimed also to determine the antibiotic sensitivity profiles of Helicobacter pylori isolates prevalent in the area. Forty-three subjects with precancerous lesions (chronic gastritis, chronic atrophic gastritis, intestinal metaplasia and dysplasia) of the stomach were randomized to one of two antioxidant treatments. Treatment 1 (250 mg of standard vitamin C, 200 mg of vitamin E and 6 mg of beta-carotene three times a day) or treatment 2 (150 mg of standard vitamin C, 500 mg of slow release vitamin C, 75 mg of vitamin E and 15 mg of beta-carotene once a day) for 7 days. Blood levels of total vitamin C, beta-carotene and alpha-tocopherol and gastric juice levels of ascorbic acid and total vitamin C were measured before and after treatment on day 8. Both treatments increased the plasma levels of total vitamin C, beta-carotene and alpha-tocopherol/cholesterol but not those of ascorbic acid or total vitamin C in gastric juice. Treatment 1 was the best choice and resulted in a greater increase in the plasma levels of beta-carotene and alpha-tocopherol. H. pylori was cultured from 90% of the gastric biopsies; 35 isolates were identified which were highly resistant to metronidazole, a front-line antibiotic recommended against H. pylori in other settings.
Assuntos
Antioxidantes/uso terapêutico , Infecções por Helicobacter/prevenção & controle , Helicobacter pylori , Lesões Pré-Cancerosas/prevenção & controle , Neoplasias Gástricas/prevenção & controle , Vitaminas/uso terapêutico , Adulto , Idoso , Antioxidantes/análise , Ácido Ascórbico/administração & dosagem , Ácido Ascórbico/sangue , Ácido Ascórbico/uso terapêutico , Carotenoides/administração & dosagem , Carotenoides/sangue , Carotenoides/uso terapêutico , Quimioprevenção , Doença Crônica , Progressão da Doença , Feminino , Suco Gástrico/química , Gastrite/tratamento farmacológico , Gastrite Atrófica/tratamento farmacológico , Helicobacter pylori/efeitos dos fármacos , Helicobacter pylori/isolamento & purificação , Humanos , Masculino , Metaplasia , Pessoa de Meia-Idade , Projetos Piloto , Venezuela , Vitamina E/administração & dosagem , Vitamina E/sangue , Vitamina E/uso terapêutico , Vitaminas/análise , Vitaminas/sangue , beta CarotenoRESUMO
The authors propose a method to perform a combined analysis of matched and unmatched case-control studies that is based on an adaptation of logistic regression and can be performed using standard software. This methodology can be used to do pooled analyses of studies with different designs. Likelihood ratio tests can be performed to assess association, heterogeneity, or trend. The standard errors of the coefficients allow the derivation of a Wald test and the calculation of confidence intervals. Another application is to compare relative risk estimators for the same risk factors studied in different phases of a disease in an effort to explore factors that may be more important in one phase than in another. Interaction terms of risk factors with variables that code the different pooled studies can be used for this purpose. The advantage of using this method is that a formal statistical comparison can be performed in which the regression coefficients of the interaction terms estimate the relative differences in risk (odds ratio ratios) between the studies. This estimation can be adjusted for other confounder factors. Two examples of application using data from case-control studies on cervical cancer and colorectal cancer are presented to illustrate the use of this epidemiologic method.
Assuntos
Estudos de Casos e Controles , Métodos Epidemiológicos , Medição de Risco , Colômbia/epidemiologia , Neoplasias Colorretais/epidemiologia , Neoplasias Colorretais/etiologia , Feminino , Humanos , Modelos Logísticos , Masculino , Análise de Regressão , Estudos Retrospectivos , Fatores de Risco , Parceiros Sexuais , Fumar/efeitos adversos , Fumar/epidemiologia , Espanha/epidemiologia , Neoplasias do Colo do Útero/epidemiologia , Neoplasias do Colo do Útero/etiologia , Displasia do Colo do Útero/epidemiologia , Displasia do Colo do Útero/etiologiaRESUMO
Data from four case-control studies on invasive cervical cancer and on cervical intraepithelial neoplasia grade III (CIN III) that were concurrently conducted in Spain and Colombia were used to look for factors that might favor the progression from CIN III to the invasive stage. These studies were compared in two ways; a case-case comparison and an estimation of the ratio of odds ratios with the use of of special logistic regression model that took into account the different design of each study and possible confounding factors. Variables studied were human papillomavirus status, viral load, viral types, sexual behavior, sexually transmitted diseases, reproductive patterns, oral contraceptives, and smoking. Both CIN III and invasive cervical cancer have a very similar profile of risk factors and none of them was different in a consistent way to suggest a role in the progression from CIN III to invasive cervical cancer. Some methodological problems such as cohort-specific differences and some selection biases could be adjusted for with a careful statistical analysis. Other problems derived from the cross-sectional nature of the design are unavoidable and should be considered in the interpretation of the results.
Assuntos
Transformação Celular Neoplásica/patologia , Displasia do Colo do Útero/patologia , Neoplasias do Colo do Útero/patologia , Adulto , Estudos de Casos e Controles , Colômbia/epidemiologia , Feminino , Humanos , Pessoa de Meia-Idade , Infecções por Papillomavirus/complicações , Paridade , Análise de Regressão , Estudos Retrospectivos , Fatores de Risco , Comportamento Sexual , Infecções Sexualmente Transmissíveis/complicações , Fatores Socioeconômicos , Espanha/epidemiologia , Neoplasias do Colo do Útero/etiologiaRESUMO
A human papillomavirus (HPV) type 16 virus-like particle-based ELISA was used to assess antivirion immune responses in 300 women participating in cervical cancer case-control studies in Colombia and Spain. Virion IgG antibodies were detected in the sera of 51% and 59% of women with HPV-16 DNA-positive invasive cervical cancer and 81% and 73% of women with HPV-16 DNA-positive cervical intraepithelial neoplasia grade III (CIN III) in Colombia and Spain, respectively. Capsid antibodies were detected in 22% and 3% of cancer controls (P < .001) and in 43% and 10% of CIN III controls (P = .010) from Colombia and Spain, respectively. Since Colombia has an 8-fold higher incidence of cervical cancer, these results demonstrate an association between ELISA positivity and cancer risk. Capsid antibody responses did not correlate with humoral responses of the same women to HPV-16 E6 and E7 oncoproteins.