Dietary fat and risk of lung cancer in a pooled analysis of prospective studies

Harvard School of Public Health, Department of Nutrition, Boston, Massachusetts 02115, USA. Lung cancer rates are highest in countries with the greatest fat intakes. In several case-control studies, positive associations have been observed between lung cancer and intakes of total and saturated fat, particularly among nonsmokers. We analyzed the association between fat and cholesterol intakes and lung cancer risk in eight prospective cohort studies that met predefined criteria. Among the 280,419 female and 149,862 male participants who were followed for up to 6-16 years, 3,188 lung cancer cases were documented. Using the Cox proportional hazards model, we calculated study-specific relative risks that were adjusted for smoking history and other potential risk factors. Pooled relative risks were computed using a random effects model. Fat intake was not associated with lung cancer risk. For an increment of 5% of energy from fat, the pooled multivariate relative risks were 1.01 [95% confidence interval (CI), 0.98-1.05] for total, 1.03 (95% CI, 0.96-1.11) for saturated, 1.01 (95% CI, 0.93-1.10) for monounsaturated, and 0.99 (95% CI, 0.90-1.10) for polyunsaturated fat. No associations were observed between intakes of total or specific types of fat and lung cancer risk among never, past, or current smokers. Dietary cholesterol was not associated with lung cancer incidence [for a 100-mg/day increment, the pooled multivariate relative risk was 1.01 (95% CI, 0.97-1.05)]. There was no statistically significant heterogeneity among studies or by sex. These data do not support an important relation between fat or cholesterol intakes and lung cancer risk. The means to prevent this important disease remains avoidance of smoking

Intake of fruits and vegetables and risk of breast cancer: a pooled analysis of cohort studies.

Context: Some epidemiologic studies suggest that elevated fruit and vegetable consumption is associated with a reduced risk of breast cancer. However, most have been case-control studies in which recall and selection bias may influence the results. Additionally, publication bias may have influenced the literature on associations for specific fruit and vegetable subgroups. Objective: To examine the association between breast cancer and total and specific fruit and vegetable group intakes using standardized exposure definitions. Data Sources/Study Selection: Eight prospective studies that had at least 200 incident breast cancer cases, assessed usual dietary intake, and completed a validation study of the diet assessment method or a closely related instrument were included in these analyses. Data Extraction: Using the primary data from each of the studies, we calculated study-specific relative risks (RRs) that were combined using a random-effects model. Data Synthesis: The studies included 7377 incident invasive breast cancer cases occurring among 351825 women whose diet was analyzed at baseline. For comparisons of the highest vs lowest quartiles of intake, weak, nonsignificant associations were observed for total fruits (pooled multivariate RR, 0.93; 95% confidence interval [CI], 0.86-1.00; P for trend = .08), total vegetables (RR, 0.96; 95% CI, 0.89-1.04; P for trend = .54), and total fruits and vegetables (RR, 0.93; 95% CI, 0.86-1.00; P for trend = .12). No additional benefit was apparent in comparisons of the highest and lowest deciles of intake. No associations were observed for green leafy vegetables, 8 botanical groups, and 17 specific fruits and vegetables. Conclusion: These results suggest that fruit and vegetable consumption during adulthood is not significantly associated with reduced breast cancer risk

Intakes of vitamins A, C and E and folate and multivitamins and lung cancer: A pooled analysis of 8 prospective studies

Intakes of vitamins A, C and E and folate have been hypothesized to reduce lung cancer risk. We examined these associations in a pooled analysis of the primary data from 8 prospective studies from North America and Europe. Baseline vitamin intake was assessed using a validated food-frequency questionnaire, in each study. We calculated study-specific associations and pooled them using a random-effects model. During follow-up of 430,281 persons over a maximum of 6-16 years in the studies, 3,206 incident lung cancer cases were documented. Vitamin intakes were inversely associated with lung cancer risk in age-adjusted analyses; the associations were greatly attenuated after adjusting for smoking and other risk factors for lung cancer. The pooled multivariate relative risks, comparing the highest vs. lowest quintile of intake from food-only, were 0.96 (95% confidence interval (CI) 0.83-1.11) for vitamin A, 0.80 (95% CI 0.71-0.91) for vitamin C, 0.86 (95% CI 0.76-0.99) for vitamin E and 0.88 (95% CI 0.74-1.04) for folate. The association with vitamin C was not independent of our previously reported inverse association with β-cryptoxanthin. Further, vitamin intakes from foods plus supplements were not associated with a reduced risk of lung cancer in multivariate analyses, and use of multivitamins and specific vitamin supplements was not significantly associated with lung cancer risk. The results generally did not differ across studies or by sex, smoking habits and lung cancer cell type. In conclusion, these data do not support the hypothesis that intakes of vitamins A, C and E and folate reduce lung cancer risk. © 2005 Wiley-Liss, Inc

A case-control study of human immunodeficiency virus infection and cancer in adults and children residing in Kampala, Uganda

Uganda offers a unique setting in which to study the effect of human immunodeficiency virus-1 (HIV-1) on cancer. HIV-1 is prevalent there, and cancers which are known to be HIV-associated, such as Kaposi's sarcoma and Burkitt's lymphoma, are endemic. Adults residing in Kampala, Uganda, presenting with cancer in city hospitals were interviewed and had an HIV test. Of the 302 adults recruited, 190 had cancers with a potentially infectious aetiology (cases). The remaining 112 adults with tumours not known to have an infectious aetiology formed the control group. In addition, 318 children who were also Kampala residents were recruited and tested for HIV: 128 with cancer (cases) and 190 with non-malignant conditions (controls). HIV seroprevalence was 24% in adult controls and 6% in childhood controls. The odds of HIV seropositivity among cases with specific cancers (other than Kaposi's sarcoma in adults) were compared with that among controls, using odds ratios (ORs), estimated with unconditional logistic regression. All ORs were adjusted for age (<5, 5-14, 15-19, 30-44, 45+) and sex and, in adults, also for the number of lifetime sexual partners (1 or 2, 3-9, 10+). In adults, HIV infection was associated with a significantly (p < 0.05) increased risk of non-Hodgkin's lymphoma [OR = 6.2, 95% confidence interval (CI) 1.9-19.9, based on 21 cases] and conjunctival squamous-cell carcinoma (OR = 10.9, 95% CI 3.1-37.7, based on 22 cases) but not with cancer at other common sites, including liver and uterine cervix. In children, HIV infection was associated with a significantly increased risk of Kaposi's sarcoma (OR = 94.9, 95% CI 28.5-315.3, based on 36 cases) and Burkitt's lymphoma (OR = 7.5, 95% CI 2.8-20.1, based on 33 cases) but not with other cancers. The pattern of HIV-associated cancers in Uganda is broadly similar to that described elsewhere, but the relative frequency of specific cancers, such as conjunctival carcinoma, in HIV-infected people differs

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. © 2003 Wiley-Liss, Inc

Meat and dairy food consumption and breast cancer: A pooled analysis of cohort studies

Background. More than 20 studies have investigated the relation between meat and dairy consumption and breast cancer risk with conflicting results. Our objective was evaluate the risk of breast cancer associated with meat and dairy food consumption and to assess whether non-dietary risk factors modify the relation. Methods. We combined the primary data from eight prospective cohort studies from North America and Western Europe with at least 200 incident breast cancer assessment of usual food and nutrient intakes, and a validation study of dietary assessment instrument. The pooled database included 351 041 women 7379 of whom were diagnosed with invasive breast cancer during to 15 year of follow-up. Results. We found no significant association between intakes of total meat, red me white meat, total dairy fluids, or total dairy solids and breast cancer risk. Categor analyses suggested a J-shaped association for egg consumption where, comp to women who did not eat eggs, breast cancer risk was slightly decreased am women who consumed <2 eggs per week but slightly increased among women who consumed ≥1 egg per day. Conclusions. We found no significant associations between intake of meat or dairy produ and risk of breast cancer. An inconsistent relation between egg consumption risk of breast cancer merits further investigation

Dairy products and ovarian cancer: A pooled analysis of 12 cohort studies

Background: Dairy foods and their constituents (lactose and calcium) have been hypothesized to promote ovarian carcinogenesis. Although case-control studies have reported conflicting results for dairy foods and lactose, several cohort studies have shown positive associations between skim milk, lactose, and ovarian cancer. Methods: A pooled analysis of the primary data from 12 prospective cohort studies was conducted. The study population consisted of 553,217 women among whom 2,132 epithelial ovarian cases were identified. Study-specific relative risks and 95% confidence intervals were calculated by Cox proportional hazards models and then pooled by a random-effects model. Results: No statistically significant associations were observed between intakes of milk, cheese, yogurt, ice cream, and dietary and total calcium intake and risk of ovarian cancer. Higher lactose intakes comparing ≥30 versus <10 g/d were associated with a statistically significant higher risk of ovarian cancer, although the trend was not statistically significant (pooled multivariate relative risk, 1.19; 95% confidence interval, 1.01-1.40; P trend = 0.19). Associations for endometrioid, mucinous, and serous ovarian cancer were similar to the overall findings. Discussion: Overall, no associations were observed for intakes of specific dairy foods or calcium and ovarian cancer risk. A modest elevation in the risk of ovarian cancer was seen for lactose intake at the level that was equivalent to three or more servings of milk per day. Because a new dietary guideline recommends two to three servings of dairy products per day, the relation between dairy product consumption and ovarian cancer risk at these consumption levels deserves further examination. Copyright © 2006 American Association for Cancer Research