Factors associated with non-epithelial ovarian cancer among Mexican women: a matched case-control study.

The purpose of this study was to identify risk factors associated with the development of non-epithelial ovarian cancer in Mexican women. A case-control study was carried out on women registered with the Mexican Institute of Social Security in Mexico City over a period of two years (1995-97). Twenty-eight new cases were recruited from the Gynecology and Obstetrics Hospital no. 4, "Luis Castelazo Ayala", and were matched by age with 84 controls selected randomly. Eighteen (64.3%) cases of germ cell tumors and 10 (35.7%) stromal sex cord tumors were found. The number of full term pregnancies was associated inversely to development of stromal sex cord tumors with lower risk in women with more than three full term pregnancies (odds ratio, 0.02: 95% confidence interval, 0.001-0.56) compared to nulliparous women. No associations were found respecting to germ cell tumors. Parity was inversely associated to development of stromal sex cord tumors, probably as a result of the endocrine system's influence on the ovaries. The development of germ cell tumors could be associated to factors not evaluated in this study.

Mexico City physicians' awareness about cervical cancer prevention: implications for cancer screening.

BACKGROUND: In spite of an early cancer detection program (CCSP), Mexico has a mortality rate for cervical cancer of 16.5 per 100,000 women. METHOD: A cross-sectional study of 330 physicians at the Mexico City General Hospital evaluated their knowledge of the CCSP, etiology, diagnostic alternatives, and treatment guidelines. Variance analysis was the statistical procedure used. Replies to a questionnaire about cervical cancer prevention awareness were scored on a scale from 1 to 9. RESULTS: According to the awareness scale, the global average classification was 4.4, with 50% of the physicians scoring 4 or less. There was no difference in the CCSP knowledge scores of gynecologists (mean 4.92, 95% CI 4.2-5.3), oncologists (mean 4.85, 95% CI 4.3-5.5), pathologists (mean 5.23, 95% CI 4.9-5.6), and those in other specialties (mean 4.29, 95% CI 4.2-5.0), p > 0.05. Many respondents attributed CCSP's lack of effectiveness to public apathy (68.12%). CONCLUSIONS: The effectiveness of the CCSP can be improved by educating health professionals if this education is combined with elimination of obstacles to its use. More information is needed to justify revising how doctors are educated in terms of not only quality of the training but also the contents of pre- and postgraduate training programs.

Epidemiology and molecular pathology of gallbladder cancer.

Gallbladder cancer is usually associated with gallstone disease, late diagnosis, unsatisfactory treatment, and poor prognosis. We report here the worldwide geographical distribution of gallbladder cancer, review the main etiologic hypotheses, and provide some comments on perspectives for prevention. The highest incidence rate of gallbladder cancer is found among populations of the Andean area, North American Indians, and Mexican Americans. Gallbladder cancer is up to three times higher among women than men in all populations. The highest incidence rates in Europe are found in Poland, the Czech Republic, and Slovakia. Incidence rates in other regions of the world are relatively low. The highest mortality rates are also reported from South America, 3.5-15.5 per 100,000 among Chilean Mapuche Indians, Bolivians, and Chilean Hispanics. Intermediate rates, 3.7 to 9.1 per 100,000, are reported from Peru, Ecuador, Colombia, and Brazil. Mortality rates are low in North America, with the exception of high rates among American Indians in New Mexico (11.3 per 100,000) and among Mexican Americans. The main associated risk factors identified so far include cholelithiasis (especially untreated chronic symptomatic gallstones), obesity, reproductive factors, chronic infections of the gallbladder, and environmental exposure to specific chemicals. These suspected factors likely represent promoters of carcinogenesis. The main limitations of epidemiologic studies on gallbladder cancer are the small sample sizes and specific problems in quantifying exposure to putative risk factors. The natural history of gallbladder disease should be characterized to support the allocation of more resources for early treatment of symptomatic gallbladder disease in high-risk populations. Secondary prevention of gallbladder cancer could be effective if supported by cost-effective studies of prophylactic cholecystectomy among asymptomatic gallstone patients in high-risk areas.

Case-control study of diabetes, obesity, physical activity and risk of endometrial cancer among Mexican women.

OBJECTIVES: Obesity, hypertension and diabetes are closely associated with endometrial cancer (EC). This study evaluates the relationship between diabetes and risk of EC on the basis of obesity. METHODS: A case control study was carried out in Mexico City from 1995 to 1997. Eighty-five histologically confirmed cases were compared with 668 population-based controls obtained through frequency matching. Diabetes status, weight, height and other factors were determined through personal interviews among both cases and controls. RESULTS: Compared to women without diabetes, those with diabetes had an adjusted odds ratio of 3.6 (95% CI = 1.7, 7.4) for EC. This association was modified by body mass index (p interaction < 0.001). Compared to non-overweight and non-diabetic women, non-overweight (OR = 3.9. 95% CI = 0.88, 18.0) and overweight (OR = 5.9, 95% CI = 1.6, 21.1) diabetic women had a non-significant elevated risk of EC. However, elevated risk estimates were observed for obese diabetic women (OR = 8.0, 95% CI = 2.8, 22.7). CONCLUSIONS: Our results strongly suggest an interaction effect between obesity and diabetes that significantly increases the risk of EC. This, in turn, may explain the growing number of new EC cases recently observed in developing countries with reduced birth rates and an increased incidence of both obesity and diabetes mellitus.

The power of information and contraceptive choice in a family planning setting in Mexico.

OBJECTIVES: This study measured the effect of information about family planning methods and STD risk factors and prevention, together with personal choice on the selection of intrauterine devices (IUDs) by clients with cervical infection. METHODS: We conducted a randomised, controlled trial in which family planning clients were assigned to one of two groups, the standard practice (control) group in which the provider selected the woman's contraceptive and the information and choice (intervention) group. The study enrolled 2107 clients in a family planning clinic in Mexico City. RESULTS: Only 2.1% of the clients had gonorrhoea or chlamydial infections. Significantly fewer women in the intervention group selected the IUD than the proportion for whom the IUD was recommended in the standard care group by clinicians (58.2% v 88.2%, p = 0.0000). The difference was even more pronounced among infected women: 47.8% v 93.2% (intervention v control group, p = 0.0006). CONCLUSIONS: The intervention increased the selection of condoms and reduced the selection of IUDs, especially among women with cervical infections, for whom IUD insertion is contraindicated.

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.

Reproductive factors of ovarian and endometrial cancer risk in a high fertility population in Mexico.

A case-control study was carried out in Mexico City during 1995-1997 among women with epithelial ovarian cancer (84 cases) and endometrial cancer (85 cases). The control group consisted of 668 healthy women, matched according to age categories. In a multivariate analysis, the reproductive risk factors for ovarian and endometrial cancer are similar. The risk of ovarian cancer was inversely related to the number of full-term pregnancies; the odds ratio (OR) was 0.17 and the 95% confidence interval (CI) was 0.05-0.54 when comparing nulliparous women versus those with more than seven pregnancies. For endometrial cancer, a similar association was observed (OR, 0.11; 95% CI, 0.04-0.34). The use of oral contraceptive hormones was inversely associated with both ovarian (OR, 0.36; 95% CI, 0.15-0.83) and endometrial cancer risk (OR, 0.36; 95% CI, 0.14-0.90). In women with a history of more than 8.7 years without ovulation, the risk of ovarian cancer decreased four times (OR, 0.23; 95% CI, 0.10-0.50), and that of endometrial cancer decreased more than five times (OR, 0.17; 95% CI, 0.08-0.35). These two neoplasms are clearly typified as hormone dependent, and it is possible to establish that "ovulation" and "exfoliative" mechanisms jointly determine the level of risk for both ovarian and endometrial cancer.

Cervical cancer screening in developing countries: why is it ineffective? The case of Mexico.

BACKGROUND: Mexico established a national cervical cancer-screening program in 1974. Despite the implementation of the program, there was a steady mortality trend of 16 per 100,000 women over 15 years. 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 non-participation. RESULTS: The low effectiveness of screening on cervical cancer is principally due to factors associated with quality and coverage. Pap quality is deficient; 64% of a random sample of specimens lacked endocervical cells. Reading centers presented false negative indices of between 10 and 54%. Women seek screening in a late stage of disease (55% with cervical cancer 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% have a history of Pap, compared with 30% in rural areas. Knowledge of what the Pap is used for strongly determines the use of screening. In rural areas, only 40% of women are informed about the purpose of the Pap test. CONCLUSIONS: A proposal to reorganize Mexico's screening program includes the following five main strategies: (a) increased coverage; (b) improved quality control of how cervical smears are taken; (c) better interpretation of Pap tests; (d) guaranteed treatment for those whose tests show abnormalities, and (e) improved follow-up.

Barriers to early detection of cervical-uterine cancer in Mexico.

In Mexico, a woman dies of cervical-uterine cancer every 2 hours, indicating a low impact by the national program for early detection of this cancer, principally because of problems related to quality and coverage. Through a qualitative study, we identified the principal barriers to use of the detection program from the point of view of actual and potential program users. Four focus groups were organized in standard conditions in Mexico City (urban, developed) and in the southern state of Oaxaca (rural, economically disadvantaged area). Participants were either women with at least one previous Papanicolaou (Pap) test or women who had never had the test. Barriers to Pap test use included (1) lack of knowledge about cervical-uterine cancer etiology, (2) not knowing that the Pap test exists, (3) the conception that cancer is an inevitably fatal disease, (4) problems in doctor/medical institution-patient relationships, (5) giving priority to unmet needs related to extreme poverty, (6) opposition by the male sexual partner, (7) rejection of the pelvic examination, (8) long waits for sample collection and receiving results, and (9) perceived high costs for care. To increase coverage of the early detection program for cervical-uterine cancer in Mexico, the needs, perceptions, and beliefs of women and their partners must be taken into account when developing policy and planning, given the role these factors play in the decision-making process that leads to their participation or nonparticipation in this program.

Prostate cancer mortality trends in Mexico, 1980-1995.

BACKGROUND: In Mexico, prostate cancer (PC) is the second highest cause of mortality by cancer in men. In 1991, there were 2,473 deaths, with a crude rate of 5.66 cases per 100,000 men age 40 or over. For this same year, the ratio of proportional mortality to the total number of malignant tumors was 12.6%. Our objectives were to determine the trends and geographic distribution of mortality for PC in Mexico for 1980-1995. METHODS: Crude and adjusted mortality rates were carried out for 1980-1995. A test for trend was done using the simple lineal regression method. The standardized mortality ratio (SMR) was calculated for 1980-1995 for each Mexican state. RESULTS: The total number of deaths by PC in Mexico for 1980-1995 was 32,349. The crude mortality rate increased during that period from 3.16 to 6.75 cases per 100,000 men over age 40. The statistical trend test with respect to time was significant (P<0.0001). The state of Southern Baja California showed a higher SMR, and a smaller SMR was shown for the state of Quintana Roo. CONCLUSIONS: The mortality trends for PC increased for the period studied. It represents a serious problem for public health. We find that the central and northern states of the country, characterized by a greater industrial and socioeconomic development, are those with a higher SMR.

[The factors that determine participation in cervical cancer screening in the state of Morelos]. / Factores que determinan la participación en el tamizaje de cáncer cervical en el estado de Morelos.

OBJECTIVE: To determine the main factors associated to participation in an early detection program of cancer (DPC), in a population with a high cervical cancer (CC) mortality rate. MATERIAL AND METHODS: A population-based, cross-sectional study was performed in the state of Morelos, which included 3,197 women aged between 15 and 49 years, randomly selected from a household sample frame of the 33 municipalities of the state. RESULTS: Awareness of the utility of the Papanicolaou (Pap) test (OR 29.6, 95% CI 23.6-37) and a former history of gynecological symptoms (OR 1.7, 95% CI 1.2-2.4) predisposed to greater use of the DPC. Factors associated to the use of the Pap test were precedents of using one contraceptive (OR 1.4, 95% CI 1.1-1.8) or two or more contraceptives (OR 2.1, 95% CI 1.6-2.8). CONCLUSIONS: In the state of Morelos, Mexico, screening for cervical cancer is offered opportunistically in the context of health care use. Therefore, the precedent of using health care services is the main determining factor for use of the DPC program. These results reveal the need to design alternative strategies to promote participation among women who have no access to health services, since they constitute the population group at highest risk of developing CC.

Evaluation of the cervical cancer screening programme in Mexico: a population-based case-control study.

BACKGROUND: This study presents the evaluation of the Mexico City Cervical Cancer Screening Programme (CCSP). Uterine cervical cancer (CC) is still a major public health problem in Mexico. Various actions aimed at reducing mortality from CC have been unsuccessful with an estimated 62000 deaths reported between 1980 and 1995. METHODS: The authors performed a study of cases and controls chosen on a population basis that included a sample of 233 cases of cancer in situ, and 397 cases of invasive cervical cancer obtained from eight hospitals, and a sample of 1005 controls representative of the general population. The results are presented stratified by case type, classified according to whether the cancer is invasive or not. RESULTS: The results show low impact of the cervical cancer screening programme in Mexico. Women who had a history of use of the Papanicolaou smear (PAP), who did not seek testing due to gynaecological symptoms and who had received their PAP results, had a 2.63 times lower risk of developing invasive cervical cancer (OR = 0.38; 95% CI: 0.28-0.52). CONCLUSIONS: The principal findings of this study in relation to the low impact of the screening programme in Mexico, are the low level of existing coverage and late use of health services by women at risk.

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.

Epidemiologic panorama of colorectal cancer in Mexico, 1980-1993.

INTRODUCTION: Colorectal cancer is the third cause of cancer-related death in the world, with 468,000 estimated deaths in 1993. In some countries mortality rates have started to decline, and survival rates have increased. In this study performed in Mexico, information is presented on the increase in mortality from this form of cancer, especially in more economically developed areas. METHODS: The mortality trend for colorectal cancer was evaluated and standardized by five-year age groups in the period 1980 to 1993. Also, the standardized mortality ratio was calculated for Mexico's 32 states, as was the possible association between mortality and indicators of rurality level and fertility rates in the different regions of Mexico. RESULTS: In the period studied, 18,962 deaths were officially reported. The average age of death was 66 years. The mortality rate among women (1.8) was significantly higher than among men (1.55 per 100,000 inhabitants). Mortality from colorectal cancer grew by 100 percent in both genders (beta = 0.089; P < 0.001), especially in the age group 34 and younger, in the 45 to 49 age group, and in the older than 75 age group (P < 0.05). The standardized mortality ratio was greater in the states in the north of Mexico. Finally, an inverse correlation was observed throughout Mexico between the rurality index (r = -0.60; P < 0.001) and the fertility rates (r = -0.43; P < 0.05) and mortality from colorectal cancer. CONCLUSIONS: In this study, there is evidence that mortality from this cancer is higher in geographic areas with greater socioeconomic development, similar to regional patterns observed in other countries. In Mexico, the coming years will see a serious epidemic in mortality from this disease; therefore, immediate attention must be given to identifying the profile of high-risk subjects and implementing early cancer detection measures.

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.

Human papilloma virus 16-18 infection and cervical cancer in Mexico: a case-control study.

Cervical cancer (CC) is one of the principal public health problems in Mexico. The national mortality rate due to CC was estimated at 21.8 per 100,000 among women over 15 years old during 1994. Despite this high incidence little is known in Mexico about the risk factors for CC. The objectives of the study were to evaluate the association between CC and HPV types 16 and 18 in women living in Mexico City. From August, 1990 to December, 1992, a case-control study was carried out in the metropolitan area of Mexico City. HPV 16-18 types were determined in a sample of 148 CC cases and 204 controls randomly selected from a sample frame representative of the metropolitan area of Mexico City. Sixty cases corresponded to in situ CC and 88 cases to the invasive phase. Determination of HPV 16 and 18 types was done by polymerase chain reaction using primers specific to E6/E7. Results showed that 48.3% of in situ CC cases and 48.8% of invasive CC cases were positive for HPV 16 while only 13.2% were positive among the 204 controls. Association between HPV 16 infection in the in situ cancer cases had an estimated odds ratio (OR) of 5.17 (95% CI 2.60-10.51). In the invasive cervical cancer cases, association between HPV 16 infection and invasive CC in this sample had an OR of 3.84 (95% CI 2.04-7.22). For the total sample, the estimated OR was 5.48 (95% CI 3.07-9.62). In the total sample, those women with a strong positive reaction to PCR were associated with a large increase in the risk, OR of 38.0 (95% CI 8.66-167.1). The prevalence the HPV 18 was 6.7%, only observed in the invasive cervical cancer cases. At present there is general consensus that HPV is the principal causal agent in C C etiology. This study intends to contribute to the knowledge concerning the etiology of cervical cancer. However, it is necessary to consider that the single most effective tool in the reduction of mortality due to cervical cancer has been the Pap test. Secondary prevention has proven to be highly effective in other populations, and this should be viewed as a priority activity for all at-risk populations. Although a vaccine for HPV may be available in the near future its efficacy in primary prevention has yet to be demonstrated.

Reproducibility study of cervical cytopathology in Mexico: a need for regulation and professional accreditation.

Due to the high rate of false negative results in diagnosis of cervical cytopathology, in many countries its practice has been transformed through the application of several interventions aimed at medical regulation to improve diagnostic accuracy. Diagnostic reproducibility of gynecological cytopathology was evaluated in a series of 20 cytology specimens [Papanicolaou (Pap)] and 20 cervical biopsy. (CB) studies in different clinical stages, during 1994. The observation unit consisted of 30 pathologists who observed 2 groups of 20 Pap and 20 CB specimens. The standard was a cytopathologist certified by the Pathological Anatomy Council of Mexico. Intraclass reproducibility in gynecological cytopathology is low in Mexico. In a group analysis, concordance increased as clinical status of the cervical lesion increased. For moderate dysplasia, concordance in Pap was kappa = 0.04, compared to 0.23 in CB. Concordance of diagnosis of invasive cancer was 0.29 for Pap and 0.64 for CB. Using weighted kappa at the individual level for all possible diagnoses, concordance varied from 0.29 to 0.59 for Pap, and 0.42 to 0.65 for CB. The problem of reproducibility in cervical cytopathology in Mexico emphasizes the need for continuing education, uniform diagnostic criteria, and the advantages of a single operational classification-possibly the Bethesda System-since current classification systems are obsolete.

[Epidemiology of cancer of the breast in Mexico. Consequences of demography transition]. / La epidemia de cáncer de mama en México. Consecuencia de la transición demográfica?

OBJECTIVE: Analyze the relation between reductions in fertility and the inverse en breast cancer mortality in the different states of Mexico for the period 1979-1994. MATERIALS AND METHODS: Fertility rates and beast cancer mortality rates were utilized to analyze the proposed relationship in the states of the country. Principal component analysis and classification analysis were then used in the confirmatory analysis of this relationship. RESULTS: There is an important decrease in fertility trends overall with regional differences: the northern states of Mexico have lowest then the southern states. These regional differences are inversely related to the observed differences in breast cancer mortality within the states: the northern states have levels of breast cancer mortality much higher than the southern states. CONCLUSIONS: The increase in mortality due to breast cancer and its relation to the decrease in fertility illustrates the importance that must be given to the preventive aspect of health services since in the near future Mexican women will exhibit reproductive behaviors similar to women in developed countries.

[Cost-benefit analysis of the Program for Early Screening of Cervico-uterine Cancer]. / Análisis costo beneficio del Programa de Detección Oportuna del Cáncer Cervicouterino.

OBJECTIVE: Previous researches pointed out the critical changes needed to increase the efficiency of the National Screening Programme of Cervical Cancer in Mexico. These changes were assessed through a cost-benefit analysis. This paper presents the results of that appraisal. Figures are presented as US Dollars of 1996 valued as 7.5 pesos for each dollar. RESULTS: The operational unitary cost of the integral process of the cytology-the obtention of the Pap smear, its transportation to the interpretation centre, its analysis, and the notification of results to users-was estimated in US$ 11.6. If the proposed changes are operated, the cost of each citology would increase by 32.7%. The benefit/cost ratio would be 2 and the net benefit of 88 millions of US dollars for the next five years. CONCLUSIONS: The operation of the proposed changes is socially desirable, but should be supported the training activities of the personnel, the increase of the coverage of women at risk, the quality control activities, the monitoring of the program and the communication with women detected as positive cases.