Concept, measurement, and data in migration analysis

Two methods of computing migration rates-one relating moves to population at risk in place of origin and the other using as a denominator the cross-product of population in places of origin and destination-are discussed. It is concluded that the second assumes implicitly that moves originate and terminate as a random population variable.Some difficulties with this particular model are pointed out and the author suggests that other analytical approaches to migration data be sought and in this connection refers to the literature on the mathematical theory of epidemics.

Mutagenic activity of nitrosated foods in an area with a high risk for stomach cancer

In a search for possible sources of mutagens in human foods, a study was made of six common foods in the diet of a population at high risk for gastric cancer (in Nariño, Colombia). No mutagenic activity was demonstrated in nonnitrosated foods. After nitrosation, only one of the foods, fava beans, demonstrated a mutagenic effect. This effect was direct and concentrated in the germ and pulp of the beans.

Ethnic variation in the incidence of stomach cancer in Illinois, 1986-1988

Wide ethnic and geographic variation in stomach cancer incidence has been reported in Eastern and Western countries. Stomach cancer is reported to be the most common malignant neoplasm in Asia, specifically, China, Japan, and Korea. In contrast, stomach cancer incidence in the United States among Caucasians is low and among blacks, moderate to low. Only one other study has directly compared the rates of stomach cancer in the three ethnic groups (i.e., white, African American, and immigrant Korean) living in the same region. The authors extend their investigation by comparing the incidence rate of stomach cancer among the same three ethnic groups in the state of illinois from 1986 to 1988. In this study, the incidence of stomach cancer was observed to be lowest in whites, intermediate in African Americans, and highest in immigrant Koreans. The overall 3-year cumulative incidence rate from 1986 to 1988 was 62.6/100,000 (95% confidence interval (CI) 38.6-86.7), 28.2/100,000 (95% CI 25.7-31), and 22.5/100,000 (95% CI 21.5-23.5) for immigrant Koreans, African Americans, and whites, respectively. The 3-year age-adjusted cumulative incidence rate for immigrant Koreans (172/100,000) was approximately four-and eightfold higher than for African Americans (41/100,000) and whites (21/100,000). The incidence of stomach cancer increased as a function of age in both sexes. Although a higher rate was observed in males than in females, these rates were four-and eightfold higher in African Americans and immigrant Koreans, when compared with their white counterparts in both sexes. Despite a substantial reduction of stomach cancer incidence in the United States and other Western countries, it remains the most frequent malignancy in native and immigrant Koreans. The high rate of stomach cancer in immigrant Koreans compared with African Americans and white populations residing in Illinois indicates either a drastically disproportionate undercount of immigrant Koreans in the 1990 census or a profound genetic-environmental interaction.

Primary brain tumor incidence rates in four United States regions, 1985-1989: a pilot study

There has been controversy in the last decade over whether the reported increase in brain tumors reflects a real increase in incidence rates. Incidence data on the full spectrum of brain tumors is lacking in the discussion since current cancer reports in the United States are restricted to malignant tumors. Data on tumors from four population-based cancer registries in the United States were compiled to provide incidence rates of benign and malignant brain tumors and to assess the feasibility of providing these data on a larger scale. A total of 8,070 primary tumors diagnosed from 1985 to 1989 in Connecticut, Massachusetts, Missouri and Utah were obtained. Brain tumors were defined using the International Classification of Diseases for Oncology codes 191.0-191.9, 192.0-192.3, 192.8-192.9 and 194.3-194.4. Stratum-specific incidence rates by location and histology were estimated by sex, age and region. Age-adjusted rates were standardized to the 1970 United States population. An age-adjusted incidence rate of 9.4/10(5) was observed, which reflects a 36% increase in males and a 68% increase in females over the rate based on malignant tumors alone from the Surveillance, Epidemiology and End Results cancer reporting system. Incorporating benign tumors into cancer registry data would increase the reported incidence rates primarily in females and for meningiomas and nerve sheath tumors. This expanded incidence rate represents a substantial improvement in the ability to describe the occurrence of these complex tumors by subtype with a modest increase in overall case registrations for cancer registries. Centralization of data on all brain tumors appears feasible. Variations in histology-specific rates across regions raises questions that need to be addressed about the ascertainment and accuracy of tumor classification. Use of the cancer registration system to improve the reporting of brain tumors in the United States is important to our understanding of the occurrence of these complex tumors and to our ability to conduct large-scale epidemiologic investigations.

[Risk factors for cancer of the esophagus: a case control study in a metropolitan area of south-eastern Brazil]

The association between esophageal cancer and smoking and drinking habits, instruction and nutritional factors was examined by means of the utilization of data of a case-control study which was undertaken in the city of S. Paulo (Brazil). Eighty five cases were compared with two hundred and ninety two hospital controls, with different diseases, including other kinds of cancer. The crude estimations of the odds ratios were calculated for all the variables. Logistic regression was used in the next steps of the analysis. The drinking habit [odds ratio = 3.68, 95% confidence interval (1.74 - 7.78)], the smoking habit [odds ratio 4.86; 95% confidence interval (1.95 - 12.13)] and the frequent eating of hot pepper [odds ratio = 2.48; 95% confidence interval (1.46 - 4.23)] are important risk factors for the disease. The estimate of odds ratio for smoking ordinary cigarette was 3.43 (1.31-8.97) and for smoking of corn straw hand-rolled cigarrette was of 4.18 (1.38-12.66).

Large bowel cancer following gastric surgery for benign disease: a cohort study

Early studies suggested that gastric surgery for benign ulcer disease was associated with a subsequent increase in the risk of large bowel cancer. Dietary fats, altered bacterial flora, and secondary bile acids are considered to play a major role in the disease etiology. Gastric surgery is known to alter bile salt metabolism as well as bacterial flora in the colon. This cohort study was designed to investigate the risk of large bowel cancer following gastric surgery for benign ulcer disease and to identify potential patient and treatment characteristics that may be associated with this risk. A cohort of 15,983 males was selected from Department of Veterans Affairs hospital admissions in 1970 and 1971. The exposed group (n = 7,609) included all males treated with gastric surgery (resection or vagotomy and drainage) for benign ulcer disease. The unexposed group (n = 8,374) was a random sample of all other male patients from the same time period and database. All subjects were followed through 1989 to identify vital status and cause of death. Deaths were identifiable by computerized linkage of the subjects' social security numbers with the Department of Veterans Affairs Beneficiary Identification Record Locator System and the National Death Index. The cause of death was documented by two certified nosologists from the death certificates of 99% of the deceased patients. Statistical analyses included estimations of risk based on standardized mortality ratios and standardized risk ratios. In this selected cohort, no increase in large bowel cancer risk was detected (risk ratio = 0.81, 95% confidence interval 0.62-1.05). The type of surgical procedure, ulcer diagnosis, age at the time of surgery, and length of follow-up did not alter the risk estimates. Unlike the previously identified increase in gastric cancer risk following ulcer surgery, no elevation in the risk of large bowel cancer following such surgery was detected in this study. Factors that may alter gastric surgery sequelae and resultant site-specific cancer risks deserve further investigations.

A cohort study of stomach cancer risk in men after gastric surgery for benign disease

BACKGROUND

For the past 40 years, investigators have suggested that there exists an increased risk of stomach cancer following gastric surgery for benign disease. Recent cohort studies have consistently identified an increased risk of stomach cancer beginning 20 years or more following gastric surgery. Validation of this association and elucidation of risk factors related to gastric cancer have been complicated by variability in study designs.

PURPOSE

This cohort study was designed to investigate the risk of stomach cancer following gastric surgery and to identify patient and treatment characteristics that may alter this risk.

METHODS

Medical admission records of 17077 male military veterans hospitalized during 1970-1971 in U.S. Department of Veterans Affairs (VA) hospitals were examined. From this initial cohort, 1094 patients who died within the 1st year following gastric surgery were excluded. Data analysis was performed on the final cohort consisting of 15,983 patients divided into the following two groups: 1) an exposed group (gastric surgery group) that included 7609 patients receiving gastric surgery for a documented benign disorder and 2) an unexposed group (comparison group) that included 8374 male patients randomly selected from all other hospitalized male patients in the patient database. The comparison group was matched to the gastric surgery group by age (within 10 years), race, hospital, and year of admission. Mortality follow-up utilized the following three sources to identify vital status: 1) the VA Patient Treatment File (1970-1988), 2) the VA Beneficiary Identification Record Linkage System (1970-1989), and 3) the National Death Index (1979-1988). Death certificates were obtained for 99% of the deceased patients. Analyses included estimations of risk using standardized rate ratios (SRRs) and proportional hazards techniques.

RESULTS

A statistically significant increase in risk of stomach cancer was demonstrated among males during the 20 years following gastric surgery (SRR = 1.9; 95% confidence interval [CI] = 1.3-2.4; P = .0001). The risk of developing gastric cancer was greatest during the 2nd to 5th postoperative years (SRR = 2.8; 95% CI = 1.6-4.5; P < .01) and during years 11-15 (SRR = 2.5; 95% CI = 1.2-4.8; P < .01). Also, the risk of developing gastric cancer was greatest among those treated by gastrectomy for any type of ulcer (SRR = 2.6; 95% CI = 1.2-4.9; P < .01) and those having any type of gastric surgery when the primary diagnosis was gastric ulcer (SRR = 2.9, 95% CI = 1.4-5.3; P < .01).

CONCLUSIONS

This study confirms that men undergoing gastrectomy for benign disease and men receiving any gastric surgery for gastric ulcer are at increased risk for developing gastric cancer. Unlike earlier studies, we find that the increased risk is not delayed for 20 years.

Gastric precancerous process in a high risk population: cohort follow-up

In an attempt to characterize the natural history of the gastric precancerous process, 1422 residents of a high risk area of Nariño, Columbia, have been followed from 3-16 years (average 5.1) with repeated gastric biopsies, for a total of 7290 person-years. The original cohort consisted of 1788 individuals yielding a successful completion rate of 79.5%. Comparison of initial and subsequent biopsies revealed a very complex dynamic flow of both progressive and regressive events, suggesting sporadic environmental forces of modulation. One-time measurement of gastric juice, pH, and nitrite failed to predict future events in the gastric mucosa. The net loss of individuals whose gastric mucosa initially showed normal histology or superficial gastritis was 3.3%/year, representing a net gain of 1.7% for chronic atrophic gastritis, 0.9% for intestinal metaplasia, and 0.7% for dysplasia. The incidence rate of gastric cancer in this population was 0.16/100 person-years. The net rates of progression were higher and those of regression lower in older compared to younger individuals. The general pattern detected is that of a slow forward movement in the previously described hierarchical organization of precursor lesions. The presence of progressive as well as regressive changes and the slow pace of change offer special opportunities to inhibit progression through intervention strategies targeting previously identified etiological factors. The difficulties and opportunities offered by the long term follow-up studies as well as the congruency of the findings with current etiological hypotheses are discussed.

Gastric precancerous process in a high risk population: cross-sectional studies

The gastric precancerous process is evaluated in 1788 participants in a gastroscopy survey in the population of Nariño, Colombia, which has one of the highest gastric cancer incidence rates on record. A detailed histological classification is used, and a hierarchical distribution of lesions is described with the main stages being gland neck hyperplasia, atrophy (gland loss), intestinal metaplasia and dysplasia. Acute inflammation was not found to be a specific stage in the sequence but rather a common finding in all stages of the precancerous spectrum. Indices of disease progression for the different steps are calculated and found to increase with gastric pH and nitrate and nitrite content of the gastric juice. The effects of high pH and nitrite content are intimately correlated. Relative risks of specific lesions, namely, hyperplasia, atrophy, metaplasia, and dysplasia, increase linearly with higher pH, nitrate, and nitrite values in the gastric juice. The severity of atrophy correlates with the prevalence of metaplasia, suggesting a sequential relationship between the described stages, a finding supported by all parameters examined. The model of progression described may serve as a basis for comparisons with populations at different levels of gastric cancer risk but it fails to provide information concerning the time required for each change, which should be provided by follow-up (cohort) studies.

Risk factors of gastric precancerous lesions in a high-risk Colombian population. II. Nitrate and nitrite

Gastric nitrite content was studied in relation to precancerous lesions of the stomach in a case-control study conducted in a high-risk Colombian population. The proportion of detectable nitrite in gastric juice and the mean pH were significantly higher among those with precancerous lesions (chronic atrophic gastritis, intestinal metaplasia, and dysplasia) than among the controls (normal and superficial gastritis); the proportion and mean pH increased with the progression of histological changes from normal to dysplasia. Nitrite was not detectable in gastric juice with a pH less than 5.0. A positive association was found between the proportion of detectable nitrite and the risk of gastric precancerous lesions. Odds ratios of 4.39 for intestinal metaplasia and 24.72 for dysplasia remained significant after controlling for confounders. This finding suggests that nitrite may be a precursor of a mutagen that targets gastric epithelial cells.

Risk factors of gastric precancerous lesions in a high-risk Colombian population. I. Salt

A case-control study for stomach cancer was conducted in a high-risk population in Nariño, Colombia to determine the risk of gastric precancerous lesions associated with salt intake measured by sodium-to-creatinine ratio of a single urine sample. Gastric biopsies and urine samples were collected from 263 individuals. Urinary sodium-to-creatinine ratios were studied in relation to histological data from the biopsies. Significantly high odds ratios for precancerous lesions (chronic atrophic gastritis, intestinal metaplasia, and dysplasia) were associated with higher sodium-to-creatinine ratios. Adjusted odds ratios (OR) of 2.50 for chronic atrophic gastritis and 7.24 for dysplasia were found. The association with intestinal metaplasia was weaker and not significant (OR = 1.57). Furthermore, an excess risk associated with adding salt to food at the table was found among patients with precancerous lesions (OR = 1.80). These findings support the two-step involvement of salt in the process of gastric precancerous lesions.

A case-control study of large bowel cancer and hormone exposure in women

Several lines of evidence indicate a potential role for hormonal or reproductive factors in the subsequent development of large bowel cancer in women. To evaluate the relationship between hormone exposure and large bowel cancer a case-control study was carried out in 18 Illinois hospitals. Female cases, ages 45-74 (n = 90), and controls (n = 208) were identified from an ongoing large bowel cancer study. Data were obtained from medical records, personal interviews, and a subsequent mail survey with a questionnaire specific to hormone usage. Menopausal estrogen use was found to be protective with respect to the subsequent development of large bowel cancer with an odds ratio of 0.6 (95% CI, 0.33-0.99). This effect remained after controlling individually for age at diagnosis, ever pregnant (yes/no), parity, age at first birth, hysterectomy with documented oophorectomy, cholecystectomy, and appendectomy. Simultaneous adjustment, using logistic regression, for age at diagnosis, parity, hysterectomy, and cholecystectomy resulted in an adjusted odds ratio for menopausal estrogen use and large bowel cancer of 0.5 (95% CI, 0.27-0.90). Subsite analysis revealed the protective effect to be strongest for the rectal cancer cases. These data support the hypothesis that exogenous hormones may alter the risk of large bowel cancer in women.

Dietary vitamins A and C and lung cancer risk in Louisiana

The authors describe the results of a hospital-based incident case-control study of lung cancer conducted in a high-risk region of southern Louisiana from January 1979 through April 1982. Dietary intake of carotene, retinol, and vitamin C was estimated from food frequency questionnaires administered to 1253 cases and 1274 controls. An inverse association was found between level of carotene intake and lung cancer risk, and this protective effect was specific for squamous and small cell carcinoma (odds ratio [OR] = 0.84, 95% confidence interval: 0.64-1.09, high intake). A stronger protective effect for these tumors was associated with dietary vitamin C intake (OR = 0.65, 0.50-0.87, high intake). A significant inverse gradient in risk with retinol intake was limited to adenocarcinoma (OR = 0.64, 0.44-0.94, high intake) and more pronounced among blacks.

Genetic etiology of gastric carcinoma: II. Segregation analysis of gastric pH, nitrate, and nitrite

A study of gastric pH, nitrate, and nitrite in 110 families collected as part of a cohort from the Narino region of Colombia is presented. All three traits are familial and have a significant linearly increasing age trend. Gastric pH has a clear bimodal distribution but does not show Mendelian segregation. The nitrate distribution is slightly skewed, but generational heterogeneity explains the data best. Gastric nitrite is also biomodal with a clear break at concentration 1.08 micrograms/ml, and 74% of the observations at zero concentration; it shows a recessive Mendelian segregation with significant residual spouse correlation. This model also fits the data best when nitrite is dichotomized into detected (measurable) and undetected values. The estimated frequency of the recessive allele is .57, so that an estimated 32% of the population sampled are recessives. Recessives whose spouses have measurable nitrite have an estimated penetrance of 99.3% at age 30 years, whereas those whose spouses have zero or undetected nitrite have a penetrance of only 8.8% at age 30 years. It appears that gastric nitrite, and, from our previous study of these families, chronic atrophic gastritis are important biologic markers for the early identification of persons predisposed to gastric cancer.

Cigarette smoking and invasive cervical cancer

A case-control study of 480 patients with invasive cervical cancer and 797 population controls, conducted in five geographic areas in the United States, included an evaluation of the relationship of several cigarette smoking variables to cervical cancer risk. Although smoking was correlated with both age at first intercourse and number of sexual partners, a significant smoking-related risk persisted for squamous cell carcinoma after adjustment for these factors (relative risk, 1.5). The risk of squamous cell cancers increased significantly with intensity and duration of smoking. Twofold excess risks were seen for those smoking 40 or more cigarettes per day and those smoking for 40 or more years. In addition, users of nonfilter cigarettes were at particularly high risk. Increased risks, however, were observed only among recent and continuous smokers. In contrast to squamous cell cancer, no relationship was observed between smoking and risk of adenocarcinoma or adenosquamous carcinoma (n = 63). These results suggest a causal relationship between cigarette smoking and invasive squamous cell cervical cancer, perhaps through a late-stage or promotional event, although the mechanisms of action require further elucidation.

Diet and chronic atrophic gastritis: a case-control study

A hospital-based case-control study of gastric cancer precursor lesions was conducted in a high-risk black population in southern Louisiana. Ninety-three subjects with biopsy-proved advanced chronic atrophic gastritis were compared to two control series: a gastroscopy clinic series and a general hospital-admission series. Dietary case-control differences indicated a protective effect associated with fruit and vegetable intake and with dietary vitamin C and a risk elevation associated with milk consumption. The protective effect associated with consumption of fruits, vegetables, and vitamin C is consistent with findings for gastric cancer and with the etiologic hypothesis of intragastric nitrosation. A twofold increased risk was associated with cigarette smoking. Gastric juice pH, NO3-, and NO2- were determined for subjects undergoing gastroscopy, and comparisons were made between this high-risk U.S. group and a Colombian population with a much greater magnitude of risk; the latter had higher NO3- and NO2- levels. An increase in pH was associated with increasing severity of gastric lesions. Levels of pH and NO2- concentration were significantly correlated (P less than .0005); however, in Louisiana the large difference in NO2- concentration associated with pH elevation is not associated with histopathologic severity. Divergent trends with severity of lesions for NO3- concentration were seen in the two populations.

The first fifty years of the Connecticut Tumor Registry: reminiscences and prospects

The first fifty years of the Connecticut Tumor Registry (1935-1985) have seen unprecedented progress in the collection of standardized data on cancer patients and in the processing of these data, from paper documents to punch cards and magnetic tapes. The need for collecting such information was first recognized, in the early 1930s, by a group of physicians, health professionals, and laymen in New Haven who observed alarming increases in cancer rates and poor survival of cancer patients in this city. This paper recalls the growth and development of the registry and the role played by the Connecticut legislature, the State Medical Society, the Connecticut Department of Health, and the National Cancer Institute in this process. For half a century, the registry has provided assistance to practitioners, hospitals, and research scientists, not only in Connecticut but across the country and around the world. By making available reliable data on incidence and survival, the registry has played a key role in patient management, clinical trials, and etiologic studies. It has also demonstrated the value and served as an exemplary model of a population-based registry. At this juncture in its history, prospects for the future of the Connecticut Tumor Registry appear bright. Its data base will be an essential resource for the recently established Cancer Control Research Unit (CCRU) in the state and for new intervention studies by investigators at Yale, the University of Connecticut, and the State Health Department.

Genetic etiology of gastric carcinoma: I. Chronic atrophic gastritis

Scientific evidence has accumulated to show that chronic atrophic gastritis (CAG) is a precursor of gastric carcinoma, especially its intestinal histologic type; thus the etiology of CAG is of interest. Data on 110 families (557 individuals) collected as part of a large cohort from the Narino region of Colombia, South America, are analyzed to determine the familiality of CAG as a risk factor, and the possible involvement of a major gene in its etiology. We found that age and having an affected mother are important risk factors. In the sample, 45% are affected; 56% of individuals above 30 are affected, whereas only 28% of those 30 and under are affected; 48% of those with affected mothers are affected, but only 7% of those with unaffected mothers are affected. A positive spouse association was confounded with age. Sex and an affected father are not significant risk factors. The genetic (segregation) analysis showed Mendelian transmission of a recessive autosomal gene with penetrance dependent on age and mother's CAG status. Homozygous recessives account for an estimated 61% of the sampled population and have penetrance reaching 72% at age 30 if the mother is affected, and 41% if the mother is not affected. Carriers and non-carriers, who make up an estimated 39% of the sampled population, have an appreciable estimated risk after age 50. The environment, particularly diet, as the sole determinant of CAG needs reevaluation; some combined action of genes and environment seems more plausible.

Urinary sodium-to-creatinine ratio as an indicator of gastric cancer risk

The difficulties in the estimation of daily intake of sodium chloride in populations are discussed. Total daily output calculations are hindered by the difficulties investigators encounter in obtaining accurate 24-hour urine collections in field work situations. As an alternative, urinary sodium-to-creatinine ratios were investigated. Such ratios, which do not change significantly with circadian excretion rhythms, are useful indicators of the amount of sodium excreted in the urine. Preliminary observations in Colombian populations at high and low risk of gastric cancer indicated higher sodium excretion in the high-risk group. Loss of sodium by other means, especially perspiration, needs to be estimated in some other way.

Correlations of values of micronutrients in sera with gastric pathology

Sera were collected in a high-risk area for stomach cancer in Colombia from 857 residents who had been gastroscoped. The levels of 6 micronutrients (retinol, beta-carotene, ascorbic acid, vitamin E, prealbumin, retinol-binding protein) were measured and the mean values correlated with the presence of gastric pathology thought to represent precursors of stomach cancer. Two micronutrients showed important variations in mean levels by gastric pathology: beta-carotene and vitamin E. Beta-carotene levels were low in patients with dysplasia, but no differences were detected for retinol levels.

Dietary determinants of gastric cancer in south Louisiana inhabitants

In south Louisiana, 391 recently diagnosed gastric cancer patients and an equal number of controls were interviewed. Questions asked covered residential and occupational histories, environmental exposures, tobacco use, diet, alcohol consumption, and pertinent demographic characteristics. Elevated relative risks were found for use of tobacco and alcohol products. Diet was found to be the main determinant of gastric cancer risk in south Louisiana. Both dietary patterns and dietary risk factors differed for blacks and whites, although fruits as a group and dietary vitamin C were found to exert strong protective effects for both blacks and whites. Consumption of smoked foods and homemade or home-cured meats increased risk of gastric cancer for blacks but not for whites. The findings are discussed in the light of the prevailing etiologic hypotheses.

Serum micronutrient levels in relation to gastric pathology

As part of an ongoing cohort study of gastric cancer precursors in Nariño, Colombia, blood levels of ascorbic acid, vitamin E, retinol, pre-albumin, retinol binding protein and carotenoids were measured and correlated with histopathologic findings of gastric biopsies. Carotene levels in both sexes and vitamin E levels in males were significantly lower in subjects with gastric dysplasia than in subjects with normal mucosa and subjects with less advanced gastric lesions (chronic atrophic gastritis and intestinal metaplasia). No other significant correlations were found.

Sodium intake and gastric cancer

To test the hypothesis that excessive intake of sodium chloride is a factor in gastric carcinogenesis, urinary excretion of sodium and creatinine was measured in Colombian subjects. Age, sex, weight, and height regression slopes for creatinine excretion were more similar in Colombia than in other countries. Sodium/creatinine (S/C) ratios correlated with 24-h urinary excretion of sodium revealed higher sodium excretion in populations with higher gastric cancer rates. The S/C ratios were not affected by circadial rhythms, making it possible to use single urine samples to investigate interpopulation differences in sodium excretion.

The impact of vaginal cytology on cervical cancer risks in Cali, Colombia

The role of vaginal cytology screening in preventing invasive carcinoma of the cervix was investigated in Cali, Colombia. The history of previous participation in screening programs was obtained from 204 patients with invasive carcinoma and from 2 sets of age-matched controls: one from the same health center and one for the same neighborhood of the patient. Our results show that the risk of developing invasive carcinoma is at least 10 times greater in non-screened than in screened women.

Passive smoking and lung cancer

Questions about the smoking habits of parents and spouses were asked in a case-control study involving 1338 lung cancer patients and 1393 comparison subjects in Louisiana, USA. Non-smokers married to heavy smokers had an increased risk of lung cancer, and so did subjects whose mothers smoked. There was no association between lung cancer risk and paternal smoking. The association with maternal smoking was found only in smokers and persisted after controlling for variables indicative of active smoking. It is not clear whether the results reflect a biological effect associated with maternal smoking or the inability to control adequately for confounding factors related to active smoking. This preliminary finding deserves further investigation.

An epidemiologic study on carcinoma of the breast following irradiation for benign conditions in infancy and childhood

To investigate the relationship of irradiation during infancy and childhood to the subsequent development of carcinoma of the breast, 996 eligible patients were studied at Evanston Hospital, Evanston, Illinois, and Northwestern Memorial Hospital, Chicago. This was a case-control study, with those in the control group being selected from concurrent hospital admissions for nonmalignant surgical conditions. A second group consisting of those with benign biopsy results was also studied. The Mantel-Haenszel method of analysis, controlling for age and race, was used to estimate the approximate relative risk of carcinoma of the breast in the irradiated group compared with that for the nonirradiated group. The type of radiation history included radiotherapy for mastitis or enlarged thymus (nine patients), irradiation of the head and neck (69 patients), diagnostic fluoroscopies (ten patients) and miscellaneous irradiation (52 patients) for bursitis, eczema or keloid. Based upon the data obtained from the results of this study and its analysis, we conclude that there is little evidence of increased risk of carcinoma of the breast after irradiation about the head, neck and chest areas for benign conditions in the population being studied herein. Such a risk, if indeed it exists at all for this population, is estimated to be about 10 per cent.

Trends in cancer incidence in Cali, Colombia

Trends in cancer incidence from 1962 to 177 provided by the cancer registry of Cali, Colombia, are presented. A decline in rates of cancer of the oral cavity, esophagus, and larynx, has coincided with an increase in the rates of lung cancer in women of all ages and in men over 65 years of age. No such rise in lung cancer has been detected in young males. Colon cancer incidence has increased, and a larger proportion of tumors in later years is concentrated around the sigmoid colon. Cervical cancer incidence has declined, but carcinoma in situ of the cervix is being more frequently diagnosed probably as a consequence of vaginal cytology screening programs. Similarities of these findings with those of Puerto Rico and contrasts with trends in the United States and Europe are discussed.

Diet and gastric cancer: nutrition survey in a high-risk area

A nutrition survey was done in four Colombian villages situated in the rural area of Nariño, previously identified as exhibiting different levels of risk for gastric cancer and its precursor lesions. The survey was based on personal visits by trained interviewers to a random sample of families in each village. The major findings of the survey reflected a higher consumption of fava beans in villages with high indices of gastric cancer risk and a higher consumption of fresh fruits and vegetables in villages where such indices were lower. Excessive salt intake and lower potassium intake in villages with a high risk of gastric cancer were suggested, but further work is required to test this preliminary observation. A generally low intake of animal proteins and a high intake of cereals in Nariño did not discriminate between villages at different levels of risk to gastric cancer and its precursors.

Socio-economic class differences in cancer incidence in Cali, Colombia

Based on census tract information, cancer incidence rates for three socio-economic strata of the city of Cali, Colombia, were calculated. Strong negative associations with socio-economic status were found for cancers of the cervix and stomach. Colon cancer and endocrine-related cancers were positively associated with socio-economic status, while no such association was found for rectal cancer. Contrary to data from developed countries, all smoking-related cancers were positively associated with socio-economic class. The role of socio-economic gradients in developing countries is stressed as a basis for etiological research.

[Epidemiology of cancer of the esophagus in São Paulo, Brazil]

São examinados aspectos da incidência de câncer do esôfago para residentes no município de São Paulo, (Brasil), no ano de 1975. Dados coletados pelo Registro de Câncer mostram um coeficiente de 6,4 e 1,3 por cem mil homens e mulheres, respectivamente; quando padronizados pela "população mundial" os coeficientes são 9,2 e 2,0 por cem mil. As taxas do sexo masculino mostram que São Paulo está a um nível de risco maior do que outras três cidades brasileiras, com dados conhecidos, Fortaleza, Recife e Rio de Janeiro; no sexo feminino não há evidências de diferenças, a não ser possivelmente em relação a Fortaleza. As curvas de incidência específica segundo idade e sexo concordam com o padrão descrito por Higginson e Muir; valores para a inclinação do 1nI (incidência específica por idade) nas idades 35 a 75 foram 5,7 para o sexo masculino e 4,4 para o feminino, ajustando-se uma linha reta. Os nativos de São Paulo apresentam uma menor incidência do que os nascidos fora da cidade; para as duas categorias de imigrantes brasileiros residentes de São Paulo, as incidências para homens são consistentemente altas. As razões masculino-feminino de incidência apresentam regularidade nos grupos brasileiros; entre os estrangeiros as razões são maiores.

Atherosclerosis and polyps of the colon. Quantification of precursors of coronary heart disease and colon cancer

The prevalence of adenomatous and hyperplastic polyps of the colon and the degree of involvement of the aorta by atherosclerotic lesions were evaluated in 842 autopsies from New Orleans. A positive statistical association between the two variables was found in white males under 75 years of age. In black males a positive correlation between atherosclerotic lesions and adenomatous (but not hyperplastic) polyps was found. The most extensive involvement of the aorta by atherosclerosis was found in patients in whom adenomatous and hyperplastic polyps coincided. The possibilities that dietary factors may account for these findings and its relevance in relation to colon cancer and coronary heart disease are discussed.

Morbidity from cancer in La Paz, Bolivia

Data from a population-based Cancer Registry in La Paz, Bolivia, are presented. The city is located at approximately 4,000 meters above sea level and has a strong cultural influence consisting of Aymará Indians immigrating from the altiplano. Incidence rates in females are high for cancer of the cervix, the gallbladder and the thyroid gland. Males display unusually high rates of testicular cancer. Stomach cancer rates are lower than among other Andean populations. Smoking-related cancer and cancers related to sex-hormones are lower than average in incidence. Cancer of the nasal mucosa and paranasal sinuses is unusually high in frequency.

Screening--does it apply to breast cancer?

Developments in the field of mammography as an adjunct screening procedure conducted at the Health Insurance Plan of Greater New York (HIP) are reviewed. As technology improves, new, non-invasive procedures for breast cancer screening may be proposed. Their test will pose the same problems encountered in the HIP trial: the definition of a control population receiving "conventional" screening; the rescreening of study and control women at specified intervals; the ability to maintain standardized diagnostic and treatment procedures for asymptomatic positives; long-term follow-up to determine whether a measurable reduction in breast cancer mortality in the study population has been achieved. These technical questions are capable of resolution and new or revised breast cancer screening modalities will be proposed, tested and possibly adopted in future years.

A case-control study of large bowel cancer in Japan

This investigation of diet and other environmental factors reports on 588 patients with colorectal cancer and 1,176 hospitalized controls in three prefectures of Japan. Weak (not statistically significant) positive effects were found for social class and urbanization. The significant association of colorectal cancer with consumption of beef, string beans, or starches previously described for Hawaiian Japanese were not reproduced here. An association with hakusal (cabbage) agreed with other reports on a negative association with cruciferous vegetables. An analysis of the subset of cases in the low rectum yielded results similar to those for the total series. The failure to uncover important food effects in Japan is attributed to the difficulty of detecting case-control differences in areas with homogeneous diet practices. Further epidemiologic research aided by leads from ongoing work with animals may provide ideas for more sharply defined questions, should stress new approaches for more accurate diet histories, and should continue to emphasize tumor localization.

Premalignant lesions of the cervix in women of Cali, Colombia

A detailed histologic study was made of uterine cervices from 441 autopsy specimens from the population of Cali, Colombia. Women in this city have one of the highest registered incidence rates of cancer of the uterine cervix. The following prevalence (in percent) of lesions in adult women was found: cervicitis, 79; reserve cell hyperplasia, 14; squamous metaplasia, 41; dysplasia, 9. Contrary to expectations, no increase in prevalence of these lesions was found with age, lower socioeconomic status, or number of pregnancies. A similar study of a sample of hysterectomies performed for uterine prolapse showed approximately the same results. The findings suggest that promotional factors are more important than initiator factors in uterine cervical carcinogenesis.

Cancer and "cancer related" colorectal lesions in São Paulo, Brazil

A series of 832 necropsy specimens were studied grossly with a magnifying lens and all lesions identified were studied microscopically. The age and sex-specific prevalence of adenomatous and hyperplastic polyps is reported and results are compared with those of other populations. A correlation was made between polyps and cancer of the colon and rectum (407 cases). The data suggest that São Paulo is a community in a transitional stage between intermediate and high risk of cancer of the colon. The epidemiologic characteristics of lower rectum cancer are peculiar to some populations and appear unrelated to colon cancer. The black population of São Paulo has a higher prevalence than that reported for African negroes. The data also implicate adenomatous polyps, diverticulosis and hemorrhoids as being probably related diseases.

Epidemiologic pathology of gastric ulcer and gastric carcinoma among Japanese in Hawaii

This case-control study of Hawaiian Japanese indicated that gastric ulcer in the proximal portion of the pyloric antrum has features similar to those of gastric cancer. Such ulcers occurred at sites most frequently and most severely affected by intestinal metaplasia, although metaplasia tended to be more extensive with cancer than with ulcer. Metaplastic mucosa was more vulnerable to the action of pepsin and acid than was normal mucosa. The risk of ulceration would rise when a sufficiently lagrge area of the antrum was intestinalized and when the corpus continued to produce significant quantities of these substances. This study showed a strong association between salt intake, ulcer, and metaplasia. Significant but less dramatic associations were demonstrated between metaplasia and the use of traditional Japanese foods and smoking. The question was raised as to whether salt promotes ulceration or whether it potentiates the action of a mutagen that causes intestinal metaplasia.

Gastric cancer in Colombia. II. Case-control epidemiologic study of precursor lesions

Endoscopic surveys in the Department of Narino (Colombia) showed that natives of areas of very high risks for stomach cancer have a higher prevalence of atrophic gastritis and intestinal metaplasia than do persons born in other parts of Narino. In these surveys, diets were compared between individuals with and without evidence of these suspect precursor lesions of stomach cancer and between individuals born in the areas designated as high and low risk for stomach cancer. The composite evidence from the comparisons indicated lettuce to be negatively associated with stomach cancer and raised the possibility to a positive association for corn. The relationship of these findings to other epidemiologic evidence and the implications for applying the epidemiology of stomach cancer to the epidemiology of precursor lesions were examined.

Gastric cancer in Colombia. III. Natural history of precursor lesions

The premalignant process in the gastric mucosa was studied by gastroscopic surveys of Colombian populations, and the prevalence of superficial gastritis, chronic atrophic gastritis, and intestinal metaplasia was calculated for population samples having a very high gastric cancer risk (Nariño), very low risk (Cartagena), and intermediate risk (Cali). The prevalence of individuals with normal mucosa in successive age groups was used to estimate "depletion" curves, which were taken as indicators of the dynamics of the premalignant process in each community. Differences corresponding to the geographic variation in stomach cancer risk were found: In the high-risk areas of Nariño, around 75% of the population developed some type of gastritis by 45 years of age, whereas in the low- and intermediate-risk population of Cartagena and Cali, the proportion of such lesions did not exceed 50% at age 45 or thereafter. The effect of environmental factors in early life seemed to be important in determining the prevalence of lesions in each population.

Gastric cancer in Colombia. I. Cancer risk and suspect environmental agents

A case control study of patients discharged from hospitals revealed fourfold differences in geographic variation in stomach cancer risk within the Department of Narino (Colombia). Data from gastroscopic surveys of population groups, samples of water supplies, and urine and saliva in Narino also indicated a generally positive correlation among the following parameters: 1) gastric cancer risk, 2) prevalence of chronic atrophic gastritis and intestinal metaplasia, 3) nitrate content of well waters, and 4) nitrate excretion by the population. Urinary excretion reflected the ingestion of nitrates, and this implied a higher average intake of nitrates in the populations at high risk for stomach cancer. The Narino data could be construed as presumptive epidemiologic evidence for the role of nitrate availability in the etiology of stomach cancer.

Stomach cancer in Japan

A study of 783 patients with stomach cancer and 1,566 hospital controls in Hiroshima and Miyagi prefectures of Japan showed that farmers, representing mostly the lowest socioeconomic class, had higher risk of developing stomach cancer. The usual inverse gradient in risk by social class was in the urban population of Miyagi, but not Hiroshima, prefecture. The study in Japan did not reproduce the association of stomach cancer with consumption of salted/dried fish and salt-pickled vegetables described for the Hawaiian Japanese. Salted/dried fish and pickled vegetables were more widely used by farmers than by nonfarmers in Japan or by Japanese migrants to Hawaii. The ability to detect associations for these typical Japanese foods in Hawaii stemmed from the fact that these reduced levels of use were more completely expressed by the Hawaiian-Japanese controls than by patients. The lower risk of developing stomach cancer for lettuce and celery users agreed with the Hawaiian-Japanese findings, and the combined results supported conjectures on possible protective food effects. Lettuce, in particular, warranted attention from this viewpoint, since similar findings have been consistently reported.

Developments in the epidemiology of stomach cancer over the past decade

The history of stomach cancer epidemiology is reviewed. The introduction of migrant population studies in the 1960 decade that described the critical role of exposures to this disease in early life was a key event. Companion pathology studies have indicated different epidemiological patterns for 2 histological entities, intestinal and diffuse type carcinomas, and confirmed an excess of intestinal metaplasia in populations at high risk to stomach cancer. Recent results suggest that epidemiology of stomach cancer can be transformed into the epidemiology of precursor lesions, and introduction of the fiberoptic gastroscope makes technically feasible detailed studies of the relationship of precursor lesions to suspect factors, including diet, in selected geographic areas. Nitroso compounds have been identified as candidate carcinogens and the epidemiological, pathological, and chemical data display signs of internal consistency. Feeding experiments with N-methyl-N'-nitro-N-nitrosoguanidine have led to animal models that permit a coordinated epidemiological-experimental approach to stomach cancer.

A model for gastric cancer epidemiology

It is postulated that one major subtype of gastric carcinoma ("intestinal type") is the end- result of a series of mutations and cell transformation begun in the first decade of life. The mutagen could be a nitroso compound synthesised in the upper gastrointestinal tract by the action of nitrite (i.e., from food or saliva) on naturally occurring nitrogen compounds. Under normal conditions these nitroso compounds do not reach the gastric epithelial cell, presumably because their synthesis is inhibited by antioxidants present in food or because of their inability to pass the mucous barrier. The barrier may be overcome by abrasives or irritants such as hard grains, food with high sodium-chloride concentration, or surfactants. Once the first mutation occurs, the glandular gastric epithelium is gradually changed to intestinal-type epithelium, the mucous barrier altered, and the pH elevated. Under these conditions, bacteria proliferate in the gastric cavity and facilitate the conversion of nitrates to nitrites, thereby increasing the nitrite pool and the probability of formation of mutagenic-carcinogenic nitroso compounds. This process of gastric atrophy and intestinal metaplasia goes on for 30 to 50 years until some of the individuals affected have the final mutation or cell transformation which allows the cell to become autonomous and invade other tissues.

Social class differences among patients with large-bowel cancer in Cali, Colombia

The incidence of large-bowel cancer in Cali, Colombia, for 1962-71 shows the upper socioeconomic classes to be a higher risk. This is the first report of a socioeconomic gradient in risk for this site. The gradients were most marked for cancer of the ascending through rectosigmoid colon and were minimal for cancer of the cecum and rectum. The Cali experience presents several parallels with information derived from comparisons of developed and developing countries and also appears consistent with recent information on the possible role of dietary factors in bowel cancer.