Call and recall for cervical cancer screening in a developing country: a randomised field trial.

A randomised field trial was used to assess Mexican women's response to a mailed invitation for a Papanicolaou test. A sample of 4,802 women, 20 to 64 years old, chosen at random from the Mexican Social Security Institute Register were randomly assigned to an intervention and to a control group. A letter of invitation and a reminder were sent to the intervention group. A letter was also sent to the control group at the end of the follow-up period (8.5 weeks) in order to compare the response among women who received a letter in both groups. Cumulative incidence and incidence rates were used to determine the response and the speed of response, respectively. The response among women who had received the letter was 33.5% (efficacy) in the intervention group, while 5.9% (p<0.001) in the control group attended a Papanicolaou test. For the total of women invited, the response was 20.1% (effectiveness) and 3.3% (p<0.001), respectively. The response was greater in rural areas (rural vs. urban/suburban; p = 0.002) and eldest women (50-64 vs. 20-49; p = 0. 02). The response rate was 7 times grater in the intervention than in the control group (RR = 7.1; 95% CI 5.4-9.4; p < 0.001). A mailed invitation to have a Papanicolaou test substantially increases attendance by women who receive it. A mailed reminder improves results. This strategy could be implemented in addition to the ones already in use, mainly among rural and elderly women.

Evaluation model of the Mexican national program for early cervical cancer detection and proposals for a new approach.

INTRODUCTION: An evaluation model on cervical cancer (CC) prevention in Mexico was carried out during 1990-95, using three observation units: women at risk, screening providers, and use of health services. METHODS: A diagnostic procedure of the pitfalls was applied to the following steps of the screening procedure: Pap sampling quality, cytological diagnosis validity, compliance of women, and determinants of nonparticipation. RESULTS: The low effectiveness of screening for CC is due principally to factors associated with quality and coverage. Quality of Pap is deficient; 64 percent of a random sample of specimens lacked endocervical cells. Reading centers presented false negative indices between 10 and 54 percent. Women seek screening in a late stage of disease (55 percent with CC seek care because they have symptoms). In addition, coverage is low; in women between 15 and 49 years of age in Mexico City, 64.2 percent have a history of Pap smears, compared with 30 percent in rural areas. Knowledge of what the Pap is used for strongly determines use of screening. In rural areas, only 40 percent know the purpose of the Pap. CONCLUSIONS: This information justifies an intervention to reorganize CC screening in Mexico, through strategies for improving compliance, quality, follow-up, and treatment for abnormal screens.

The cervical cancer screening program in Mexico: problems with access and coverage.

A cross-sectional study was carried out in two geographic regions of Mexico - Oaxaca (rural area) and Mexico City (urban area) - to determine the main factors for predicting participation in Cervical Cytology Screening Programs (CCSP), in populations with high mortality due to cervical cancer. We included 4,208 women aged between 15 and 49 years, randomly selected through a national household-sample frame. Knowledge of what the Pap test is used for strongly predisposes use of CCSP in Mexico City (odds ratio [OR] = 46.1, 95 percent confidence interval [CI] = 33.1-64.1) and Oaxaca state (OR = 61.5, CI = 42.0-89.9), as well as high socioeconomic level (Mexico: OR = 2.0, CI = 1.1-7.6; Oaxaca: OR = 4.1, CI = 3.1-5.3), high education level (Mexico: OR = 3.6, CI = 1.5-8.8; Oaxaca: OR = 5.3, CI = 2.8-10.0), and access to social security (Mexico: OR = 1.7, CI = 1.4-2.2; Oaxaca: OR = 2.2, CI = 1.8-2.7). Low coverage of the CCSP is confirmed as an important problem in Mexico.

The role of chemoprevention in cancer control.

Chemoprevention can be defined as the use of chemical compounds or medicines to prevent the occurrence of precancerous lesions (markers) or to slow down or revert the progression of clinically established disease. The use of randomized trial design is considered the gold standard for evaluating the preventive value of chemicals against cancer, since they control for confounding and avoid information bias. The principal school in relation to cancer control through chemoprevention is based on studies of cancer and diet. Initially, ecological studies set the cornerstone, but later case-control studies supported the hypothesis of an inverse association between foods and cancer risk (principally epithelial), suggesting that determined micronutrients participate as protection in this process. Other studies include specific chemical analyses, which have potential problems that could lead to erroneous conclusions, such as sample and measurement errors. During this decade randomized intervention trials have been carried out to test this hypothesis, but conclusions have been so diverse and the designs used have been so different in terms of levels of exposure, that consistent conclusions are not possible. We can conclude that using studies with randomized, double-blind, controlled designs is interesting, but problems remain to be solved, including: agent selection, the design to be chosen, and especially the balance between benefits sought and secondary effects, including cost-effectiveness, since some chemicals cannot compete with other preventive or therapeutic measures.

Prevalence of precancerous lesions of the stomach in Venezuela.

Gastric biopsies from 1477 participants in a chemoprevention trial for precancerous lesions of the stomach in Venezuela were evaluated for the prevalence of precancerous lesions and Helicobacter pylori infection. These study subjects were selected from participants in an early detection program for gastric cancer using double-contrast X-ray. Overall, 94% had some type of chronic gastritis (CG) and were positive for H. pylori using Giemsa stain, 49% had atrophic gastritis, 34% had intestinal metaplasia (IM), and 6.5% had dysplasia. There were only three subjects (0.2%) with normal gastric mucosa, and 4% had only superficial gastritis. The prevalence of all of these precancerous lesions increased with age, but there was no clear difference by gender. The prevalence of the various lesions was higher in the antral mucosa than in the fundic mucosa. H. pylori infection was strikingly frequent in our study population, with prevalence rates ranging from 73% in subjects with superficial gastritis to 95% in those with atrophic gastritis and IM and 98% in those with CG. The prevalence of H. pylori was equally high in males and females, and it was significantly positively associated with the degree of infiltration of poly- and mononuclear cells and with that of active regeneration; it was inversely correlated with the degree of atrophy, IM, and dysplasia. Our findings support the precancerous nature of the various gastric lesions and the etiological role of H. pylori infection in CG.

Chemoprevention trial on precancerous lesions of the stomach in Venezuela: summary of study design and baseline data.

A double-blind, placebo-controlled trial is being conducted in a population at high risk for gastric cancer in Venezuela. The main aim of the trial is to assess the effect of antioxidant vitamins (beta-carotene, vitamin C and vitamin E) in blocking the progression of precancerous lesions of the stomach. Within the framework of a screening programme for stomach cancer, 2200 subjects of 35-69 years of age have been recruited. At study entry, a dietary questionnaire was completed, and gastroscopy with the collection of seven gastric biopsies was performed. After baseline examinations, the study participants were randomized to receive antioxidant treatment or placebo for three years. The treatment phase will be completed in mid-1998. At the end of the treatment phase, the investigations performed at study entry will be repeated. Before the initiation of the trial, various pilot studies were carried out that showed an extremely high prevalence of Helicobacter pylori infection (over 90%). Two eradication trials using anti-H. pylori treatments that give good results in Europe and North America gave very poor results in our study population. The low eradication rates achieved (5-20%) suggest a high prevalence of antibiotic-resistant H. pylori strains or high reinfection rates. These disappointing results led to deletion of an anti-H. pylori treatment phase of the main trial.

[Gastrointestinal system tumors in Italian emigrants]. / I tumori dell'apparato gastroenterico nei migranti italiani all'estero.

In this paper we present the risk of death for stomach, colon, rectum and pancreas cancers in Italian migrants to Canada, Argentina, Australia, France and England and Wales. Estimations of relative risks (RR) in Italian migrants, in residents in Italy and in Southern Italy relative to the local born in the host country are shown. Relative risks in Italian migrants to Australia were analysed also by duration of stay in the host country. The Italian migrants' cancer profile in intermediate between the origin and the host population: a reduction of risk of death for stomach cancer and an increase of risk for colorectal cancers are the main results. The results are discussed taking into account the analysis by duration of residence and the pattern of food prevalent in the different countries considered.

Difficulty in eradicating Helicobacter pylori in a population at high risk for stomach cancer in Venezuela.

The bacterium Helicobacter pylori (HP) has been implicated in the etiology of precancerous lesions of the stomach and there is evidence suggesting that it may influence the efficacy of chemoprevention of gastric cancer with vitamin C. Eradication seldom has been attempted in populations from developing countries, with a high prevalence of HP frequently resistant to metronidazole. A randomized, double-blind, controlled trial to evaluate the efficacy of colloidal bismuth subcitrate (120 mg q.i.d.) and amoxycillin (500 mg q.i.d.) in eradicating HP was conducted in 220 subjects drawn from a population with a high prevalence of metronidazole-resistant HP in Tachira state, Venezuela. One month after completion of two weeks' treatment, eradication rates of 6.5 percent in the treatment group and two percent in the placebo group were estimated on the basis of HP diagnosis in biopsies, and of 13.9 percent compared with 3.9 percent on the basis of a 14C-urea breath test, although the negative predictive value of the breath test was very low compared with HP diagnosis in biopsies. In the treatment group, particularly among males, a significant decrease in bacterial load was detected. Reasons for failure of treatment in high HP-prevalence areas are discussed, and it is suggested that primary prevention of HP infection may be the optimal approach to reducing levels of stomach cancer in these high-risk groups.