Southern cooking and lung cancer

The consumption of coffee and black tea and the risk of lung cancer

PURPOSE

Coffee and black tea are among the most consumed beverages worldwide. Although their potential role in lung cancer occurrence has been investigated in several studies, results have been inconclusive. We investigated the associations between intake of coffee and black tea with lung cancer in a population-based case-control study in Montreal, Canada.

METHODS

These analyses included 1130 cases and 1483 controls. Adjusted odds ratios (ORs) were estimated between four metrics of coffee and black tea consumption (frequency, average daily amount, duration, and cumulative amount) and lung cancer, using unconditional logistic regression.

RESULTS

The adjusted ORs (95% confidence intervals) for lung cancer comparing daily to never consumers were 0.73 (0.49-1.10) for coffee and 1.05 (0.85-1.31) for black tea. Analyses of other metrics did not reveal any clear patterns of increasing or decreasing risk with increasing amounts or duration of consumption. There was no strong evidence of OR modification by sex or smoking level. The OR estimates did not materially differ by histological subtype for either of the beverages.

CONCLUSION

Our results do not provide strong support for associations between consumption of coffee and black tea and lung cancer.

A prospective study of meat, cooking methods, meat mutagens, heme iron, and lung cancer risks

BACKGROUND

Red and processed meat consumption may play a role in lung cancer pathogenesis because of these meats' fat and carcinogen content.

OBJECTIVE

We prospectively investigated whether meat type, cooking method, doneness level, and intake of specific meat mutagens and heme iron are associated with lung carcinoma.

DESIGN

Men (n = 278,380) and women (n = 189,596) from the National Institutes of Health-AARP Diet and Health Study with no history of cancer at baseline were monitored for 8 y. Diet was assessed with a 124-item food-frequency questionnaire. A meat-cooking module was used to estimate the intake of individual heterocyclic amines, benzo(a)pyrene, and heme iron. Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% CIs.

RESULTS

In a comparison of quintiles 5 with 1 (Q5vsQ1), a high intake of red meat was associated with an increased risk of lung carcinoma in both men (HR(Q5vsQ1): 1.22; 95% CI: 1.09, 1.38; P for trend = 0.005) and women (HR(Q5vsQ1): 1.13; 95% CI: 0.97, 1.32; P for trend = 0.05). A high intake of processed meat increased the risk only in men (HR(Q5vsQ1): 1.23; 95% CI: 1.10, 1.37; P for trend = 0.003). In an analysis stratified by smoking status, we observed a tendency for an increased risk with red meat intake in never smoking men and women; however, the risks were not statistically significant. In a comparison of tertiles 3 and 1 (T3vsT1), the risk of lung carcinoma was associated with intake of well-/very-well-done meat (HR(T3vsT1): 1.20; 95% CI: 1.07, 1.35; P for trend = 0.002) and the intake of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (HR(Q5vsQ1): 1.20; 95% CI: 1.04, 1.38; P for trend = 0.04) in men. Heme iron intake increased the risk of lung carcinoma in both men (HR(Q5vsQ1): 1.25; 95% CI: 1.07, 1.45; P for trend = 0.02) and women (HR(Q5vsQ1): 1.18; 95% CI: 0.99, 1.42; P for trend = 0.002).

CONCLUSION

We observed a moderate association between meat consumption and lung carcinoma, which might be explained by heme iron intake, high-temperature cooking, and associated mutagens.

Cruciferous vegetable consumption and lung cancer risk: a systematic review

BACKGROUND

Cruciferous vegetables, rich in isothiocyanates, may protect against lung cancer. Glutathione S-transferases are important in metabolizing isothiocyanates; hence, variants in GST genes may modify the association between cruciferous vegetable intake and lung cancer. We carried out a systematic review to characterize the association between cruciferous vegetable intake and lung cancer risk, with an emphasis on the potential interaction between cruciferous vegetables and GSTM1 and GSTT1 gene variants.

METHODS

A search of the epidemiologic literature through December 2007 was conducted using 15 bibliographic databases without language restrictions. Thirty studies on the association between lung cancer and either total cruciferous vegetable consumption (6 cohort and 12 case-control studies) or specific cruciferous vegetables (1 cohort and 11 case-control studies) were included.

RESULTS

The risk for lung cancer among those in the highest category of total cruciferous vegetable intake was 22% lower in case-control studies [random-effects pooled odds ratio, 0.78; 95% confidence interval (95% CI), 0.70-0.88] and 17% lower in cohort studies (pooled relative risk, 0.83; 95% CI, 0.62-1.08) compared with those in the lowest category of intake. The strongest inverse association of total cruciferous vegetable intake with lung cancer risk was seen among individuals with GSTM1 and GSTT1 double null genotypes (odds ratio, 0.41; 95% CI, 0.26-0.65; P for interaction = 0.01).

CONCLUSIONS

Epidemiologic evidence suggests that cruciferous vegetable intake may be weakly and inversely associated with lung cancer risk. Because of a gene-diet interaction, the strongest inverse association was among those with homozygous deletion for GSTM1 and GSTT1.

Fruits, vegetables and lung cancer: a pooled analysis of cohort studies

Inverse associations between fruit and vegetable consumption and lung cancer risk have been consistently reported. However, identifying the specific fruits and vegetables associated with lung cancer is difficult because the food groups and foods evaluated have varied across studies. We analyzed fruit and vegetable groups using standardized exposure and covariate definitions in 8 prospective studies. We combined study-specific relative risks (RRs) using a random effects model. In the pooled database, 3,206 incident lung cancer cases occurred among 430,281 women and men followed for up to 6-16 years across studies. Controlling for smoking habits and other lung cancer risk factors, a 16-23% reduction in lung cancer risk was observed for quintiles 2 through 5 vs. the lowest quintile of consumption for total fruits (RR = 0.77; 95% CI = 0.67-0.87 for quintile 5; p-value, test for trend < 0.001) and for total fruits and vegetables (RR = 0.79; 95% CI = 0.69-0.90; p-value, test for trend = 0.001). For the same comparison, the association was weaker for total vegetable consumption (RR = 0.88; 95% CI = 0.78-1.00; p-value, test for trend = 0.12). Associations were similar between never, past, and current smokers. These results suggest that elevated fruit and vegetable consumption is associated with a modest reduction in lung cancer risk, which is mostly attributable to fruit, not vegetable, intake. However, we cannot rule out the possibility that our results are due to residual confounding by smoking. The primary focus for reducing lung cancer incidence should continue to be smoking prevention and cessation.

Diet as risk for lung cancer: a Swedish case-control study

A case-control study was undertaken to study lung cancer in relation to dietary habits, occupational exposure, and living in urban or country areas. Suspect lung cancer cases in West Sweden and population controls were interviewed using a food frequency questionnaire. The study comprised 177 female and 359 male cases and 916 controls. The cases mainly comprised former and current smokers (82% female, 95% male). For the analysis, cases were divided into the histological diagnoses adenocarcinoma and squamous cell, small cell, and adenosquamous cell carcinomas, as well as into smoking categories. A high frequency of consumption of vegetables was significantly related to a lower risk for adenocarcinoma and squamous cell and adenosquamous cell carcinoma among men and adenocarcinoma among women. A low odds ratio in the highest quartile of vegetable consumption in men was seen in all smoking categories. There were no significant protective effects from fruit in the different lung cancer subgroups, although a significant trend was found for heavy-smoking females. A high consumption of milk was related to an increased risk for lung cancer, especially adenosquamous cell carcinoma. The results suggest that the protective effect or risk due to dietary factors may affect different forms of lung cancer. The results from this as well as previous studies suggest a complex interaction between diet and lung cancer risk, involving the types of lung cancer as well as consumption patterns in the population.

The reliability of dietary data for self- and next-of-kin respondents

BACKGROUND

In case-control studies, recalled dietary data from next-of-kin are sometimes used as a surrogate measure of exposure; however, there is limited evidence comparing the ability of study participants and next-of-kin surrogates for the reliability of their responses with respect to past dietary recall.

METHODS

We compared dietary information from 303 subjects who were administered a food frequency questionnaire in 1980 with that from 196 of the same subjects and 107 next-of-kin of deceased subjects 5 years later, but with reference to 1980 diet. Agreement between 1980 and 1985 reporting with respect to food groups, food preparation methods, and adherence to special diets was primarily assessed using the kappa statistic.

RESULTS

The concordance between 1980 and 1985 reporting of specific food groups was generally poor. Regarding various methods of cooking meats and the use of different types of cooking fats, next-of-kin respondents showed very poor agreement with the reporting of their deceased relatives, and within-subject agreement was also poor for frying meats, baking meats, and for cooking with margarine and vegetable oil. Subjects and next-of-kin were able to reproduce earlier reporting of a special ulcer diet, but not diabetic or low-salt diets. Overall, subjects tended to have better agreement with their own earlier reporting than did next-of-kin, and spouses were found to be more reliable next-of-kin respondents than other relatives.

CONCLUSIONS

Dietary data collected retrospectively from next-of-kin may be unreliable.