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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.

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.

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.

For the study of both proliferative and antigenic changes in epithelial cells in a disease predisposing to gastric cancer, endoscopic biopsy specimens were analyzed following removal from individuals with chronic atrophic gastritis (CAG); comparisons were made with specimens from normal gastric mucosa. All subjects were from Nariño, Colombia, the population of which has a high age-adjusted incidence of gastric cancer (150/100,000 population) occurring mainly in gastric antrum. After pulse incubation of biopsy specimens with tritiated thymidine ([3H]dThd), microautoradiographic distributions of [3H]dThd-labeled cells in the epithelial lining of gastric pits were correlated with expression of serologically defined gamma-fetal antigen (FA) as a second marker. Measurements were done both in gastric corpus and in antrum for entire gastric pits and over multiple gastric pit compartments. Total numbers of cells per gastric pit column did not differ between the normal and the CAG specimens either in corpus or in antrum; however, both in corpus and in antrum mean numbers of [3H]dThd-labeled cells per gastric pit column and labeling index were almost twice as large for the CAG population (P less than .006). Labeling index differences also were significant over most gastric pit compartments (P less than .02). In antrum gamma-FA-positive lesions had an expanded proliferative compartment with labeling indices significantly greater than those of antigen-negative lesions (P less than .02). This correlation did not extend to biopsy specimens obtained from corpus of stomach where the frequency of carcinoma is low. Findings indicate a hyperproliferative state in CAG compared to the proliferative state in normal gastric mucosa and, in gastric antrum, a further correlation with expression of gamma-FA in hyperproliferating cells. The two markers can be used to aid definition of the gastric mucosa in a disease associated with the development of gastric cancer and in prophylactic dietary intervention programs.

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.

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.

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.

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.

Samples of gastric contents from 2 groups of patients from a region of high risk for gastric cancer were analyzed for pH, nitrite, nitrate, thiocyanate, and chloride. In each group, the patients could be divided into 2 subgroups: those with a gastric pH of less than 5 and those with a gastric pH of greater than 5. Above pH 5, nitrite was correlated with nitrate. The pH greater than 5 subgroups had significantly higher (P less than 0.01) nitrite content (20- to 100-fold). Some high- and low-nitrite samples were also analyzed for macro and trace metal ions, but differences were not significant. This is the first report in which patients with diagnosed gastric pathology related to a precancerous state were shown to have high levels of a putative carcinogen precursor. The results were compatible with our original hypothesis of intragastric nitrite formation by bacterial reduction of nitrate and concomitant synthesis of carcinogenic N-nitroso compounds.