Processed meat consumption and risk of cancer: a multisite case-control study in Uruguay

BACKGROUND

The role of processed meat in the aetiology of several cancers was explored in detail.

METHODS

In the time period 1996-2004, a multisite case-control study was conducted in Montevideo, Uruguay. The study included 6 060 participants (3 528 cases and 2 532 controls) corresponding to cancers of the oral cavity, pharynx, oesophagus, stomach, colon, rectum, larynx, lung, female breast, prostate, urinary bladder, and kidney (renal cell carcinoma only).

RESULTS

The highest odds ratios (ORs) were positively associated with cancers of the colon, rectum, stomach, oesophagus, and lung. With the exception of renal cell carcinoma, the remaining cancer sites were significantly associated with elevated risks for processed meat consumption. Furthermore, mortadella, salami, hot dog, ham, and salted meat were strongly associated with risk of several cancer sites.

CONCLUSION

It could be concluded that processed meat intake could be a powerful multiorgan carcinogen.

Dietary folate intake and the risk of 11 types of cancer: a case-control study in Uruguay

BACKGROUND

There is limited, but inconclusive, epidemiological evidence that high folate intake decreases the risk of colorectal and esophageal cancers. For other cancer sites, the evidence is even less consistent or extensive.

MATERIALS AND METHODS

We conducted a case-control study of dietary folate intake and risk of 11 cancer sites in Uruguay between 1996 and 2004, including 3539 cancer cases and 2032 hospital controls. Unconditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) of cancer associated with folate intake.

RESULTS

In the multivariable model, there was a significant decrease in the risk of cancers of the oral cavity and pharynx (OR = 0.49, 95% CI 0.24-0.98), esophagus (OR = 0.29, 95% CI 0.14-0.60), upper aerodigestive tract (OR = 0.41, 95% CI 0.26-0.65), colorectum (OR = 0.42, 95% CI 0.23-0.76) and kidney (OR = 0.35, 95% CI 0.13-0.93) for the highest versus the lowest quartile of dietary folate intake.

CONCLUSIONS

Our results not only confirm earlier findings of decreased risk of colorectal and esophageal cancers with a high dietary folate intake but also suggest decreased risk of several other cancers. However, we cannot exclude the possibility that residual confounding, multiple comparisons or other forms of bias could explain these results.

Food groups and risk of squamous cell carcinoma of the oesophagus: a case-control study in Uruguay

In the time period January 1998-December 2000, a case-control study on squamous cell cancer of the oesophagus was conducted in Montevideo, Uruguay. The main objective of the study was to estimate the odds ratios (ORs) associated with main food groups. For this purpose, 166 patients afflicted with squamous cell oesophageal cancer and 664 hospitalised controls were frequency matched on age and sex. Both series of patients were administered with a structured questionnaire. Aside from queries related with tobacco smoking, alcohol drinking and maté drinking, patients were interviewed with a food-frequency questionnaire (FFQ) on 64 items, representative of the usual Uruguayan diet. Red meat, salted meat and boiled meat displayed strong direct associations (OR for red meat 2.4, 95% CI 1.4-4.2). On the other hand, fish and total white meat showed moderate protective effect (OR for total white meat 0.5, 95% CI 0.3-0.9). Total fruit intake displayed a strong inverse association (OR 0.2, 95% CI 0.1-0.4), whereas total vegetable consumption presented a weak inverse association (OR for total vegetable intake 0.7, 95% CI 0.4-1.2). These results suggest that vegetables, mainly cooked vegetables, are rich in thermolabile protective substances. On the other hand, boiled (stewed) meat, which is ingested at high temperature could be, like maté, a risk factor for squamous cell cancer of the oesophagus.

Plant foods and differences between colon and rectal cancers

A case-control study on plant food intake and its role in the risk of colon and rectal cancers was carried out in Montevideo, Uruguay. Four hundred and eighty-four (484) cases of colorectal cancer and 1452 controls were frequency matched on age, sex, residence and urban/rural status. Among cases, 260 patients had colon cancer whereas 224 had rectal tumours. Controls had non-neoplastic conditions. Both cases and controls were interviewed in the four major hospitals in Montevideo shortly after admittance for diagnosis or treatment. The questionnaire included a section on frequency of foods, which included 64 items, in particular, queries on 18 vegetables, 10 fruits and 6 cereal dishes were included. Thus, the amount of plant foods consumed was complete and included the main plant foods in the Uruguayan diet. The analysis showed that rectal cancer displayed inverse associations with total plant foods, total vegetables, cooked vegetables, potatoes and legumes. When data were stratified by tumour site and sex, only men showed a protective effect of plant foods (odds ratio (OR) of rectal cancer for men 0.4, 95% confidence interval (CI) 0.2-0.7). In contrast, women with rectal carcinoma were not associated with plant food intake. It can be concluded that plant foods are protective factors for men afflicted with colorectal cancer but that plant food intake is not associated with risk in women. This is, at least in part, due to the high risk associated with bread intake in this gender.

Vegetables, fruits, related dietary antioxidants, and risk of squamous cell carcinoma of the esophagus: a case-control study in Uruguay

In 1998-1999, a case-control study on esophageal cancer was conducted in Uruguay. For this purpose, 111 cases with squamous cell carcinoma of the esophagus and 444 controls with conditions unrelated to tobacco smoking, alcohol drinking, or recent changes in the diet were frequency matched on age, gender, residence, and urban/rural status. Vegetables and, more markedly, fruits were associated with strong reductions in risk. On the other hand, 12 of 15 dietary antioxidants displayed significant inverse associations with esophageal cancer risk. The strongest effect was observed for high intake of beta-cryptoxanthin (odds ratio = 0.16, 95% confidence interval = 0.08-0.36). Also, alpha-carotene, lycopene, and beta-sitosterol were associated with significant reductions in risk. Most antioxidants lost their effect when they were further adjusted for a term for all vegetables and fruits. beta-Carotene showed an increased risk with high intakes. On the other hand, vegetables and fruits remained as significant variables after adjustment for each antioxidant, suggesting that other substances or other mechanisms could explain this effect.

Plant sterols and risk of stomach cancer: a case-control study in Uruguay

In 1997-1999, 120 incident and histologically verified cases of stomach cancer were frequency matched on age, gender, residence, and urban/rural status with 360 controls to study the role of diet in gastric cancer in Uruguay. We focused on the role of plant sterols (beta-sitosterol, campesterol, stigmasterol, and total plant sterols) after controlling for major confounders. Total phytosterols were associated with a strong inverse relationship with stomach cancer (odds ratio of stomach cancer for total phytosterol intake in the highest tertile = 0.33, 95% confidence interval = 0.17-0.65). Joint exposure to high intake of total phytosterol and alpha-carotene was also inversely associated with gastric cancer risk (odds ratio = 0.09, 95% confidence interval = 0.02-0.32). High intake of total plant sterols explained most of the attenuation in risk of gastric cancer associated with vegetable and fruit intakes.

Plant foods and risk of gastric cancer: a case-control study in Uruguay

The association between plant foods intake and gastric cancer risk was investigated in a Uruguayan study on environmental factors and cancer. The study included 160 newly diagnosed and histologically verified cases of gastric carcinoma and 320 hospitalized controls. These controls were frequency-matched to the cases on age, sex, residence and urban/rural status. Total vegetable intake was associated with a reduction in risk (odds ratio (OR) 0.64, 95% confidence interval (CI) 0.38-1.08), which was markedly attenuated after adjustment for total fruit intake. The only group of vegetables that persisted as significantly protective after controlling for total energy and total fruit consumption were allium vegetables (OR 0.56, 95% CI 0.34-0.92). On the other hand, total fruit consumption displayed a strong inverse association after controlling for total vegetable intake (OR 0.35, 95% CI 0.21-0.59). Neither tubers nor pulses were associated with gastric cancer risk. Finally, total plant foods were strongly associated with a reduced risk of stomach cancer (OR 0.31, 95% CI 0.18-0.54). It is suggested that vitamins (vitamin C and carotenoids) and bioactive substances (diallyl sulfide) could be involved in the mechanisms of action of plant foods.

Meat, fat and risk of laryngeal cancer: a case-control study in Uruguay

The effect of meat and fat in laryngeal carcinogenesis was examined in a case-control study carried out in Uruguay in the time period 1998-1999. One-hundred and forty patients with squamous cell laryngeal carcinoma and 420 hospitalized patients, afflicted with conditions not related with tobacco smoking, alcohol drinking or recent dietary changes comprised the cases and controls in this study. All patients were interviewed face-to-face in the hospitals with a detailed questionnaire which included queries on 64 food items. Red and total meat intakes were associated with strong increases in risk of laryngeal cancer (odds ratio [OR] for high total meat intake 3.32, 95% confidence interval [C.I.] 1.23-8.95). This effect disappeared after controlling for total fat intake. On the other hand, total fat intake displayed a strong association with risk of laryngeal cancer when red meat was included in the same model (OR for high fat intake 7.05, 95% C.I. 2.51-19.8). Total fat intake combines its effect multiplicatively with tobacco smoking.

Dietary carotenoids and risk of gastric cancer: a case-control study in Uruguay

In the period 1997-1999, 120 incident and histologically verified cases of stomach cancer were frequency matched on age, sex, residence and urban/rural status with 360 controls in order to study the role of diet in gastric cancer in Uruguay. Our attention was focused on the role of carotenoids in gastric carcinogenesis, after controlling for major confounders. According to the results, vitamin A, alpha-carotene and lycopene were associated with strong inverse relationships with stomach cancer (OR of stomach cancer for high alpha-carotene intake 0.34, 95% CI 0.17-0.65). Joint exposure to high intakes of alpha-carotene and vitamin C intakes were associated with a strong reduction in risk (OR 0.11, 95% CI 0.03-0.36). It was also suggested that high lycopene intake explained most of the reduction in risk of gastric cancer associated with vegetable intake, whereas no such effect was observed for fruit intake.

Plant foods and risk of laryngeal cancer: A case-control study in Uruguay

In order to examine the relationships between plant foods, defined as the grouping of vegetables, fruits, tubers and legumes, with the risk of developing laryngeal cancer, a case-control study was conducted in Uruguay between 1998-1999. The study included 148 cases with histologically verified squamous cell carcinoma of the larynx, which were frequency matched on age, residence and urban/rural status with 444 hospitalized controls, afflicted by non-neoplastic conditions. Both series of patients were face-to-face interviewed in the hospitals shortly after admittance using a detailed questionnaire. This questionnaire included 62 queries on food items, representative of the usual diet of the Uruguayan population. Food items and food groups were adjusted for tobacco smoking, alcohol drinking and total energy intake. High consumption of plant foods was associated with an OR of 0.42 (95% CI 0.21-0.84). Among subgroups of plant foods, fruits and raw vegetables were associated with a strong reduction in risk (OR for the highest quartile of raw vegetables 0.29, 95% CI 0.15-0.56). Also, legumes were associated with a protective effect (OR 0.62, 95% CI 0.33-1.19). Among individual food items, tomatoes and oranges were associated with the stronger protective effects (OR for tomato intake 0.32, 95% CI 0. 17-0.58). The joint effect of heavy smoking and the low intake of vegetables and fruits displayed an increased risk of 19.2 (95% CI 5. 7-64.9).

Vegetables, fruits, and related nutrients and risk of breast cancer: a case-control study in Uruguay

To evaluate whether the protective effect associated with vegetables and fruits in breast cancer could be explained by nutrients and bioactive substances present in these plant foods, we carried out a case-control study in Uruguay including 400 cases and 405 controls. The intake of vegetables, fruits, and related nutrients was estimated with a food frequency questionnaire on 64 food items. This questionnaire allowed the calculation of total energy intake, and nutrients were calorie adjusted by the residuals method. Odds ratios for study variables were estimated by unconditional multiple logistic regression. Total vegetable, total fruit, dietary fiber, vitamin C, vitamin E, lycopene, folate, and total phytosterol intakes were inversely associated with breast cancer risk [4th quartile odds ratio for total vegetable intake = 0.41, 95% confidence interval = 0.26-0.65, p (for trend) = 0.004]. The association with total vegetable intake was not independent of lycopene intake. The results related to vegetable and nutrient intakes are consistent with antioxidant and antiestrogenic effects. This could be mediated, among other nutrients, by dietary fiber and lycopene intake. The role of other unmeasured phytochemicals, correlated with dietary fiber and lycopene intakes, cannot be ruled out.

Alpha-linolenic acid and risk of prostate cancer: a case-control study in Uruguay

In the time period of 1994-1998, a case-control study on diet and prostate cancer was carried out in Uruguay to examine the risk associated with fat intake. Two hundred and seventeen (217) incident cases afflicted with advanced prostate cancer were frequency-matched with 431 controls on age, residence, and urban/rural status. The analysis was carried out using unconditional multiple logistic regression. Alpha-linolenic acid was associated with a strong positive association (fourth quartile of intake odds ratio, 3.91; 95% confidence interval, 1.50-10.1) after controlling for total calorie intake and for the other types of fat. The effect was similar when alpha-linolenic acid was analyzed by its sources of origin (odds ratio for vegetable linolenic acid, 2.03; 95% confidence interval, 1.01-4.07). Including this report, five of six studies that have examined the relationship between alpha-linolenic acid and prostate cancer yielded a positive association, which was significant in four studies. Thus, there appears to be evidence of a role of alpha-linolenic acid in prostate carcinogenesis.

Tomatoes, tomato-rich foods, lycopene and cancer of the upper aerodigestive tract: a case-control in Uruguay

In order to study the relationship between tomatoes, tomato products, lycopene and cancers of the upper aerodigestive tract (UADC; oral cavity, pharynx, larynx, esophagus) a case-control study was carried out in Uruguay, in the time period 1996-98. Two-hundred and thirty eight cases and 491 hospitalized controls were frequency matched on age, sex, residence and urban/rural status. Both series were submitted to a detailed questionnaire, including tobacco smoking, alcohol drinking and queries on 64 food items. These data were analyzed by unconditional logistic regression, after adjusting by total energy intake. Tomato intake was associated with a reduction in risk of 0.30 (95% confidence interval [CI], 0.18-0.51), whereas tomato sauce-rich foods displayed a protective effect of 0.57 (95% CI, 0.33-0.96 for the highest quartile of intake). The food group composed of raw tomato and tomato-rich foods showed a strong inverse association with UADC (odds ratio [OR], 0.23; 95% CI, 0.13-0.39 for the highest quartile of intake). Lycopene was also strongly associated with a reduced risk of 0.22 (95% CI, 0.13-0.37). Adjustment of tomato intake for several phytochemicals explained almost completely its protective effect, which disappears in this model. Finally, the joint effect of lycopene and total phytosterols was associated with a significant reduction in risk (OR, 0.11; 95% CI, 0.05-0.23).

Dietary iron and cancer of the rectum: a case-control study in Uruguay

In order to examine the relationship between dietary iron intake and risk of rectal cancer, a case-control study was carried out in Montevideo, Uruguay. In the time period 1994-1998, 216 newly diagnosed and microscopically verified cases of adenocarcinoma and 433 controls hospitalized for diseases not related with long-term changes in diet were enrolled in the study. Controls were frequency matched to cases on age, sex, residence and urban/rural status. Both series of patients were interviewed face-to-face in the four major hospitals in Montevideo by two trained social workers. Dietary iron was associated with significant increases in risk in men, women, and in both sexes together [odds ratio (OR) 3.2, 95% confidence interval (CI) 1.9-5.3 for the highest tertile of consumption versus the lowest one]. Since meat and its major macronutrients were potential confounders, iron intake was adjusted for these variables without major changes in the results. Furthermore, dietary iron and total fat combined its effects according to a multiplicative model (OR 3.3, 95% CI 1.8-5.8). Finally, an interaction between dietary iron and vitamin C was found. According to the results, iron displayed a significant increase in risk at low levels of vitamin C intake (OR 4.9, 95% CI 2.3-10.5). These results, together with the existing epidemiological and experimental evidence, suggest that dietary iron could play an important role in rectal carcinogenesis.

Dietary antioxidants and lung cancer risk: a case-control study in Uruguay

To examine the protective role of dietary antioxidants (carotenoids, vitamin C, vitamin E, glutathione, and flavonoids) in lung cancer risk, a case-control study involving 541 cases of lung cancer and 540 hospitalized controls was carried out in Uruguay. The relevant variables were energy adjusted using the residuals method and then categorized in quartiles. Adjusted odds ratios (ORs) for antioxidants were calculated through unconditional logistic regression. With the exception of lycopene and vitamin C, the remaining antioxidants were associated with significant reductions in risk of lung cancer. Of particular interest was the inverse association between dietary glutathione and lung cancer [OR of quartile with highest intake compared with lowest quartile = 0.42, 95% confidence interval (CI) = 0.27-0.63]. Also, carotenoids and vitamin E were associated with significant reductions in risk of lung cancer (OR = 0.43, 95% CI = 0.29-0.64 for total carotenoids and OR = 0.50, 95% CI = 0.39-0.85 for vitamin E). A joint effect for high vs. low intakes of beta-carotene and glutathione was associated with a significant reduction in risk (OR = 0.32, 95% CI = 0.22-0.46). It could be concluded that dietary antioxidants are associated with a significant protective effect in lung carcinogenesis and that the inverse association for glutathione persisted after controlling for total vegetables and fruits.

Meat intake and risk of squamous cell esophageal cancer: a case-control study in Uruguay

In order to examine the relationship between different types of meat and squamous cell cancer of the esophagus, a case-control study was carried out in Uruguay. Eighty-two cases and 248 hospitalized controls were frequency-matched on age, sex, residence and urban/rural status. All patients responded to a detailed questionnaire, which included a food-frequency form for 64 food items representative of the usual Uruguayan diet. Whereas increases in risk were observed for high intake of salted meat [odds ratio (OR) 2.5, 95% confidence interval (CI) 1.1-5.4] and lamb (OR 2.1, 95% CI 1.1-4.2), beef from cow was inversely associated with the risk of esophageal cancer (OR 0.4, 95% CI 0.2-0.9). Also, polyunsaturated fat from meat was associated with an increased risk (OR 3.2, 95% CI 1.0-9.8). Finally, total meat intake was not associated with squamous cell cancer of the esophagus.

Meat intake and risk of squamous cell esophageal cancer: a case-control study in Uruguay

In order to examine the relationship between different types of meat and squamous cell cancer of the esophagus, a case-control study was carried out in Uruguay. Eighty-two cases and 248 hospitalized controls were frequency-matched on age, sex, residence and urban/rural status. All patients responded to a detailed questionnaire, which included a food-frequency form for 64 food items representative of the usual Uruguayan diet. Whereas increases in risk were observed for high intake of salted meat [odds ratio (OR) 2.5, 95% confidence interval (CI) 1.1-5.4] and lamb (OR 2.1, 95% CI 1.1-4.2), beef from cow was inversely associated with the risk of esophageal cancer (OR 0.4, 95% CI 0.2-0.9). Also, polyunsaturated fat from meat was associated with an increased risk (OR 3.2, 95% CI 1.0-9.8). Finally, total meat intake was not associated with squamous cell cancer of the esophagus.

Foods, nutrients and prostate cancer: a case-control study in Uruguay

A case-control study of diet and prostate cancer was conducted in Montevideo, Uruguay involving 175 cases and 233 controls. When the highest quartile of intake was compared with the lowest, positive findings were obtained for red meat intake (OR 2.0, 95% CI 1.1-3.8), desserts (OR 1.8, 95% CI 0.9-3.3), total energy (OR 1.9, 95% CI 1.0-3.4) and total fat intake (OR 1.8, 95% CI 0.9-3.4). On the other hand, vegetables and fruits (OR 0.5, 95% CI 0.3-0.9), vitamin C (OR 0.4, 95% 0.2-0.8) and vitamin E (OR 0.6, 95% CI 0.3-1.1) were associated with reduced risks of prostate cancer. Possible mechanisms are discussed.

Diet and risk of cancer of the upper aerodigestive tract--II. Nutrients

In order to examine the risks of cancer of the upper aerodigestive tract (UADC) associated with nutrient intake, a case-control study was conducted in Uruguay in the period of January 1996-December 1997. All patients afflicted with cancer of the oral cavity, pharynx, larynx, and esophagus, were included in the study. Cases were frequency-matched with hospitalized patients on age, sex, residence, and urban/rural status. A strong positive association with protein intake was observed (OR 2.5, 95% CI 1.5-4.4), whereas antioxidants were associated with an inverse association (OR for vitamin C 0.5, 95% CI 0.3-0.8). Non-nutritive substances, like flavonoids displayed a marked reduction in risk of 70%. Possible mechanisms for these findings are discussed.

Diet and risk of cancer of the upper aerodigestive tract--I. Foods

In order to examine the risks of cancer of the upper aerodigestive tract associated with food groups, a case-control study was conducted in Uruguay in the period January 1996-December 1997. All patients afflicted with cancer of the oral cavity, pharynx larynx, and esophagus, were included in the study. Cases were frequency matched with hospitalized patients on age, sex, residence, and urban/rural status. A strong association with red meat intake was observed (OR 2.4, 95% CI 1.2-4.8), whereas vegetables fruits and legumes were associated with an inverse association (OR for fruits 0.3, 95% CI 0.2-0.6). Salted meat, a possible source of nitrosamines, was associated with an increased risk of 60% for esophageal cancer. Possible mechanisms for these findings are discussed.

Case-control study on the role of heterocyclic amines in the etiology of upper aerodigestive cancers in Uruguay

To examine the risk of upper aerodigestive tract cancers (UADC: oral cavity, pharynx, larynx, and esophagus) associated with dietary heterocyclic amine (HCA) exposure, a case-control study involving 140 cases and 286 controls was conducted in Montevideo, Uruguay. Beef and red meat intakes were positively associated with risk of UADC [odds ratio (OR) for red meat intake = 2.8, 95% confidence interval (CI) = 1.4-6.0], whereas no association was observed with white meat (poultry plus fish) intake. When meat intake was examined by cooking method, no association was observed for fried meat. On the other hand, broiled and boiled meat were associated with a significant increase in risk of UADC (OR for broiled meat = 2.0, 95% CI = 1.0-4.3). Total HCA intake was associated with an increased risk (OR = 2.2, 95% CI = 1.1-4.2) of UADC. The HCA effect was similar among the different cancer sites.

Meat intake, 'mate' drinking and renal cell cancer in Uruguay: a case-control study

In the period January 1988-December 1995, a case-control study of diet and renal cell carcinoma (RCC) risk involving 121 cases and 243 hospitalized controls was carried out in Montevideo, Uruguay. After adjusting for major covariates, red meat intake was associated with a 3.4 increase in risk for the highest category of intake, with a significant dose-response pattern. Also, barbecued meat, protein and heterocyclic amine intakes were associated with significant increases in risk of RCC. The consumption of the beverage known as 'mate' (a ocal tea derived from the herb Ilex paraguariensis) was associated with an increased risk of 3.0 for heavy drinkers.

Dietary sugar and lung cancer: a case-control study in Uruguay

To examine whether dietary sugar modifies lung cancer risk, a case-control study involving 463 cases with lung cancer and 465 hospitalized controls was conducted in Uruguay in the period 1993-1996. Dietary patterns were assessed in detail using a 64-item food-frequency questionnaire, which allowed the calculation of total energy intake. After adjustment for potential confounders through a model that included tobacco smoking and total energy, total fat, vitamin C, and alpha-carotene intakes, an increased risk for sugar-rich foods, total sucrose intake, sucrose to dietary fiber ratio, and glycemic index for lung cancer was observed (odds ratio for highest category of total sucrose intake = 1.55, 95% confidence interval = 0.99-2.44). When lung cancer was analyzed separately by cell type, odds ratios for small cell and large cell undifferentiated carcinoma were higher than those observed for squamous cell and adenocarcinoma of the lung. The joint effect of pack-years, total fat intake, and sucrose intake was associated with an increased risk of 28.3 (95% confidence interval = 13.4-59.7) for high values of the three variables. The study suggests that high sucrose intake could be an important risk factor in lung carcinogenesis. Further studies, both epidemiological and experimental, are needed to replicate the present findings and to clarify the mechanism(s) of sucrose intake in lung carcinogenesis.

Smoking patterns and cancer of the oral cavity and pharynx: a case-control study in Uruguay

A case-control study of cancer of the oral cavity and pharynx was conducted in Uruguay, between 1992 and 1996. 425 patients microscopically diagnosed with squamous cell carcinoma of the oral cavity and pharynx were frequently matched on age, residence, and urban/rural status with 427 hospitalised controls. The study was restricted to males. Smokers of black tobacco cigarettes were associated with an increased risk of 12.1 (95% confidence interval (CI) 7.6-19.4), when compared with non-smokers after fitting a model which included the matching variables, birthplace, education, and total alcohol consumption. Lifelong smokers of hand-rolled cigarettes displayed an odds ratio (OR) of 8.7 (95% CI 5.6-13.4), compared with non-smokers. When smokers were excluded from the calculations, the OR for smokers of black tobacco cigarettes was 3.0 (95% CI 2.0-4.6), compared with smokers of blond tobacco cigarettes, after controlling for the same variables mentioned above, plus pack-years, years since stopping, and filter use. Hand-rolling appears to be less important than smoking black tobacco in this study (OR 1.6, 95% CI 0.9-2.5). Thus, smoking black tobacco cigarettes appears to be an important habit in oral and pharyngeal carcinogenesis.

Phytosterols and risk of lung cancer: a case-control study in Uruguay

Plant sterols are substances present in vegetable oils, corn and some fruits. According to previous studies, phytosterols are protective in colon carcinogenesis. This case-control study was carried out in order to establish a possible protective role of plant sterols in lung carcinogenesis. The study was performed in Montevideo, Uruguay, during 1993-1996, and included 463 cases with lung cancer and 465 hospitalized controls. Total plant sterol intake was associated with a reduction in risk of 50% when contrasting the upper exposure quartile with the lower, after controlling for major confounders, including tobacco smoking and total energy intake. This protective effect was specially evident in adenocarcinoma of the lung (OR 0.29, 95% CI 0.14-0.63). Therefore, plant sterol intake appears to be an important variable in lung carcinogenesis. Further studies are needed in order to replicate the present findings.

Dietary nitrosamines, heterocyclic amines, and risk of gastric cancer: a case-control study in Uruguay

To study the effects of dietary chemicals like nitrosodimethylamine and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, resulting from the cooking method of red meat, on gastric carcinogenesis, a case-control study was conducted in Uruguay, a country with areas of high rates of gastric cancer. The study involved 340 cases and 698 controls, who were interviewed between January 1993 and December 1996. Dietary nitrosodimethylamine was associated with an increased risk of gastric cancer [odds ratio (OR) = 3.6, 95% confidence interval (CI) = 2.4-5.5], whereas dietary 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (a potent mutagen derived from the frying and broiling of red meat) showed an OR of 3.9 (95% CI = 2.3-6.4). Both chemicals displayed independent effects, and its interaction followed a multiplicative model with an elevated OR of 12.7 (95% CI = 7.7-21.2). These results suggest that salted and barbecued meat, frequent items in the Uruguayan diet, and the resulting chemicals from the cooking methods of both types of meat are significantly associated with a high risk of stomach cancer.

Essential fatty acids and breast cancer: a case-control study in Uruguay

The relationship between frequency of intake of different types of fat and breast cancer was investigated in a case-control study conducted in Montevideo, Uruguay, during the time period 1994-1996. Our study comprised 365 cases and 397 controls. A moderate and non-significant increase in risk of breast cancer, associated with total fat intake, was found. Saturated and monounsaturated fat intake were not associated to an increased risk of this malignancy, whereas polyunsaturated fat and linoleic acid were associated with a significantly reduced risk (OR 0.26, 95% CI 0.13-0.53). On the contrary, both alpha-linolenic acid and cholesterol intakes were associated with an increased risk of breast cancer (OR for the upper quartile of intake of alpha-linolenic acid 3.79, 95% CI 1.53-9.40). When alpha-linolenic was examined at different levels of intake, the OR's were significantly higher at low levels of linoleic acid intake (OR 7.5, 95% CI 1.9-28.8).

Tobacco smoking and alcohol drinking as risk factors for stomach cancer: a case-control study in Uruguay

OBJECTIVES

To estimate the risk of stomach cancer associated with alcohol drinking and tobacco smoking in Uruguayan men.

METHODS

A case-control including 331 cases and 622 controls was conducted in Montevideo, Uruguay, during the period 1992-96. The study was restricted to men, and both cases and controls were patients admitted to the major four hospitals in Montevideo. Response rates were high and similar for both series (92.8 for cases and 92.6 percent for controls). Controls were frequency-matched to cases on age and residence, and patients with conditions related a priori to tobacco smoking and alcohol drinking were considered ineligible for the study. All patients were interviewed shortly after admission using a structured questionnaire by two trained social workers. Relative risks, approximated by the odds ratios (OR), were estimated by unconditional logistic regression in models including major potential confounders.

RESULTS

Smoking duration was associated with an increased risk of 2.2 for smokers of more than 50 years, with a significant dose-response pattern, after controlling for major confounders. Quitters of more than 15 years displayed an OR of 1.1, very close to the risk of never-smokers. A younger age at having started smoking was associated with an increased risk, whereas pack-years of cigarettes showed a significant dose-response. Also, alcohol drinking (particularly hard liquor and beer) was associated with an OR of 2.4 (95 percent confidence interval = 1.5-3.9), after controlling for the effect of tobacco, vegetables, and other types of alcohol beverages.

CONCLUSIONS

These findings add further support to the role of tobacco and alcohol in gastric carcinogenesis.

Influence of dietary levels of fat, cholesterol, and calcium on colorectal cancer

The associations between calcium, fat, and cholesterol intake and risk of colorectal cancer were studied in a case-control study conducted in Uruguay. A total of 282 incident and histologically proven cases of adenocarcinomas of the colon and rectum comprised the case series. Five hundred sixty-four hospitalized controls were selected from the same hospitals from which the cases were drawn. Calcium intake was associated with a significant decrease in the risk of colorectal cancer (odds ratio = 0.41, 95% confidence limit = 0.24-0.69 for the uppermost quartile of intake). The associations were similar for colon and rectal cancer. On the other hand, protein and total fat were associated with significantly increased risk of colorectal cancer. A strong interaction between calcium and fat (and cholesterol) intake was found. According to this interaction, calcium effect was maximal at low levels of dietary fat (and cholesterol intake), whereas fat (and cholesterol intake) showed a positive monotonic increase in risk of colorectal cancer at high levels of calcium intake. This finding should be further investigated in other epidemiologic and experimental studies.

Consumption of tea and coffee and the risk of lung cancer in cigarette-smoking men: a case-control study in Uruguay

This study investigated the effect of drinking tea or coffee on the lung cancer risk of male cigarette smokers in a case-control in Uruguay. Four hundred and twenty-seven lung cancer cases were frequency matched on age and residence with 428 hospitalized controls suffering from conditions unrelated to tobacco smoking and diet. Whereas coffee drinking had no effect on the lung cancer risk of the cigarette-smoking men in this study, black tea consumption decreased this risk. Heavy drinkers of tea (two or more cups of tea per day) were associated with a reduced risk of 0.34 (95% CI 0.14-0.84). This protective effect was more evident among Kreyberg I tumors (squamous cell and small cell) and among light smokers. Possible sources of bias and mechanisms of action are discussed.

Sucrose as a risk factor for cancer of the colon and rectum: a case-control study in Uruguay

In order to examine the relationship between dietary sucrose intake and colorectal cancer, a case-control study was conducted in Uruguay in the time period 1992-1996. In all, 289 cases and 564 controls, admitted for diagnosis or treatment in the 4 major hospitals in Montevideo, were considered eligible for the study. Total sucrose intake was associated with a monotonic positive gradient of risks and the odds ratio (OR) for the uppermost quartile of intake was of 2.18 (95% confidence interval, CI, 1.35-3.51). Glucose intake was associated with a small and non-significant increase in risk (OR 1.46, 95% CI 0.76-2.82). Finally, an interaction between sucrose and protein intake was found, and the OR for high intakes of sucrose and protein was 6.07.

Dietary fat and lung cancer: a case-control study in Uruguay

To examine whether dietary fat and cholesterol modifies lung cancer risk, a case-control study was conducted in Uruguay of 426 men diagnosed from 1993 to 1996 with lung cancer, and 419 hospitalized frequency-matched controls. Dietary patterns were assessed using a 64-item food frequency questionnaire, which allowed the calculation of total energy intake. After adjustment for potential confounders through a model which included tobacco smoking, total energy, a term for all vegetables and fruits, and alpha-carotene intake, an increase in risk for total fat intake for all cell types of lung cancer was observed. Adenocarcinoma of the lung was associated strongly with saturated fat intake (odds ratio [OR] = 2.3, 95 percent confidence interval [CI] = 1.2-4.4), whereas small-cell lung cancer was associated with dietary cholesterol (OR = 2.8, CI = 1.1-7.5). These results suggest that the association of saturated fat and cholesterol could be type-specific, but the high correlation existing between dietary lipids precludes any strong statement about this point.

Meat intake, heterocyclic amines, and risk of breast cancer: a case-control study in Uruguay

To study the effects of meat intake, including heterocyclic amine exposure, on the risk of breast cancer, we conducted a hospital-based case-control study involving 352 patients with breast cancer and 382 controls. A strong effect of red meat, total meat, beef, fried meat, and heterocyclic amine exposure was found, after controlling for potential confounders. The odds ratio for the highest quartile of 2-amino-3-methylimidazo [4,5-f]quinoline exposure was 3.34 (95% confidence interval 1.85-6.02). According to these results, meat intake and chemicals formed during the cooking process appear to be strong risk factors in human breast carcinogenesis.

Fatty foods and the risk of lung cancer: a case-control study from Uruguay

To examine whether fatty-food consumption modifies lung-cancer risk, a case-control study involving 377 patients with lung cancer and 377 controls was conducted in Uruguay. The study was restricted to men. Dietary patterns were assessed in detail using a 64-item food-frequency questionnaire, which allowed the calculation of total energy intake. After adjustment for potential confounders (body-mass index, family history of lung cancer, total energy intake and tobacco smoking), an increase in risk for fatty-food consumption was observed. In particular, fried foods (OR, 1.54; 95% CI, 1.01-2.35), dairy products (OR, 2.85; 95% CI, 1.73-4.69) and desserts (OR, 2.52; 95% CI, 1.54-4.12) were associated with increases in lung-cancer risk and significant dose-response patterns. The association with dairy products was more evident for adenocarcinoma of the lung (OR, 4.18; 95% CI, 1.87-9.36), whereas increased risks for fried-meat and dessert consumption were observed in each cell type. The association with fried-meat consumption was more pronounced for current smokers and for heavy smokers, whereas dairy products and desserts were associated with risk both in current and in past smokers. In conclusion, fat-rich foods and sucrose-rich foods were positively associated with an increased risk of lung cancer. Although the relationship between fat consumption and lung cancer has been reported, the direct association of lung cancer with sucrose-rich foods should be further investigated.

Dietary fiber and risk of breast cancer: a case-control study in Uruguay

To examine whether dietary fiber modifies breast cancer risk, a case-control study involving 351 newly diagnosed patients with breast cancer and 356 hospitalized controls was conducted in Uruguay. Dietary patterns were assessed in detail by use of a food frequency questionnaire on 64 items, which allowed the calculation of total energy intake. Nutrient residuals were calculated through regression analysis. After adjustment for potential confounders (which included age, residence, family history of breast cancer, prior history of benign breast disease, parity, total energy, red meat, lutein/zeaxanthin and quercetin intake, and menopausal status), dietary fiber and total nonstarch polysaccharides were associated with a strong reduction in risk of breast cancer (odds ratio for uppermost quartile of total dietary fiber = 0.51, 95% confidence limit = 0.31-0.82). Also the dose-response pattern was highly significant (p < 0.001). The inverse association was observed in pre- and post-menopausal women and was similar for soluble and insoluble fiber. Furthermore, dietary fiber displayed a strong joint effect with fat, quercetin, and lutein/zeaxanthin.

Dietary nitrosodimethylamine and the risk of lung cancer: a case-control study from Uruguay

Evidence from animal studies indicates that various N-nitroso compounds are carcinogenic. We investigated whether consumption of nitrosodimethylamine (NDMA) and foods and beverages containing NDMA are carcinogenic for the lung. In a hospital-based case-control study in Uruguay, dietary intake of NDMA and its food sources was measured in 320 cases of lung cancer and 320 controls afflicted with diseases not related with tobacco use and diet. After adjusting for tobacco smoking and total energy intake, NDMA displayed a significant dose-response pattern, with a 3-fold increase in risk for the higher category of intake. The risks were slightly more elevated for adenocarcinoma of the lung. Also, salted meat consumption and beer intake were associated with an increased risk of lung cancer.

Meat consumption and risk of lung cancer; a case-control study from Uruguay

A case-control study was conducted at the Instituto Nacional de Oncologia, Uruguay, in order to investigate the relationship between meat consumption and lung cancer risk. The study included 256 cases of lung cancer and 284 controls, frequency matched with the cases on age, residence and urban/rural condition. A significant increase in risk of lung cancer associated with red meat, beef and fried meat was observed. The increase in risk was more evident in squamous cell lung cancer. This association remained after controlling for total energy and saturated fat intake, suggesting a possible role of heterocyclic amines in lung carcinogenesis.

Meat, fat and risk of breast cancer: a case-control study from Uruguay

To examine whether meat intake modifies breast-cancer risk, a case-control study was conducted in Uruguay. Dietary patterns were assessed in detail (for cases, before diagnosis or symptoms occurred) using a food frequency questionnaire involving 64 food items, which allowed total energy intake to be calculated. Nutrient residuals were calculated through regression analysis. After adjustment for potential confounders (which included family history of breast cancer, menopausal status, body-mass index, total energy and total alcohol intake), an increased risk associated with consumption of total meat intake, red meat intake, total fat and saturated fat intake was observed. The strongest effect was observed for red meat intake (OR 4.2, 95% CL 2.3-7.7) for consumption in the upper quartile, after controlling for protein and fat intake. This suggests an independent effect for meat. Since experimental studies have shown a strong effect of heterocyclic amines in rat mammary carcinogenesis, further studies should be performed in human epidemiology, perhaps using biomarkers of heterocyclic amine exposure.

Vegetables, fruits, and risk of colorectal cancer: a case-control study from Uruguay

To examine whether vegetable and fruit intake modify colorectal cancer risk, a case-control study was conducted in Uruguay. Dietary patterns were assessed in detail (for cases before diagnosis or symptoms occurred) by use of a food frequency questionnaire on 61 food items, which allowed the calculation of total energy intake. Nutrient residuals were calculated through regression analysis. After adjustment for potential confounders (which included body mass index, total energy, and total alcohol intake), a reduction in risk for total vegetable intake, total fruit intake, and lettuce, apple, and banana consumption was observed. The strongest protection was observed for banana intake (odds ratio 0.28; 95% confidence level 0.16-0.50) for consumption in the third tertile compared with the first.

Risk factors for laryngeal cancer

One hundred seven patients afflicted with incident laryngeal cancer and 290 controls with diseases considered not related to tobacco and alcohol exposure were interviewed in the University Hospital of Montevideo, Uruguay. The study followed a case-referent design, and epidemiologic analysis was carried out at the Louisiana State University, New Orleans. Dark tobacco smoking was the strongest risk factor, with an RR 2.5 times higher than that showed by light (flue-cured) tobacco smokers and 35 times that of non-smokers. Alcohol exposure displayed lesser effects but its interaction with tobacco smoking resulted in very high risks (more than 100 times higher). Among particular types of alcoholic beverages, red wine showed RR's similar to those displayed by hard liquor consumption. The habit of drinking a local tea called "mate" was associated with a threefold increase in risk, after controlling for the effects of age and tobacco and alcohol consumption. Infrequent consumption of vegetables and fruits showed RR on the order of 2.7, suggesting a role of diet in the causation of laryngeal cancer.

Esophageal cancer in Uruguay: a case-control study

Esophageal cancer has constituted a major public health problem in Uruguay, with age-adjusted death rates of 14.5 X 10(5) for males and of 3.8 X 10(5) for females. A case-control study was undertaken to ascertain the possible association of the local custom of drinking infusions of Ilex paraguariensis ("maté") with cancer of the esophagus, after controlling for well-known risk factors, such as alcohol and tobacco consumption. Two hundred twenty-six patients with esophageal cancer and 469 controls (control:case = 2.1) were interviewed at the time of admission or consultation at the Oncology Institute of Montevideo from 1979 through 1984. Males showed elevated risks of esophageal cancer associated with heavy tobacco [relative risk (RR) = 10.8] and alcohol (RR = 10.3) exposures. Among females, the independent effects of tobacco and alcohol were nonsignificant. Maté consumption had an independent effect in both males and females, with odds ratios of 6.5 and 34.6, respectively, for heavy users. Moreover, a well-defined dose response was evident in both sexes.

Carcinoma of the tonsil. A retrospective analysis of prognostic factors

A study was designed to assess clinical and pathologic variables with prognostic value in carcinoma of the tonsil. Seventy-nine cases, diagnosed and treated at the University Hospital of Montevideo, Uruguay, during a 20-year period (1960 through 1979) were studied. Survival of patients according to sex, age, performance status, tumor size (T), nodal status (N), clinical stage, tongue involvement, histologic type, grade of differentiation, and local control with treatment was analyzed with the life-table method and the statistical significance was estimated with the logrank test. Regression methods showed that the combination of T and N factors explained 25% of the prognosis. When local control was included in the equation, the predictive power increased to 52%. Local spread to the base of the tongue and female sex were of marginal significance regarding prognosis.