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.

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.

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).

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.