beta-carotene and Respiratory-Tract-Neoplasms

Topics: Animals; Anticarcinogenic Agents; beta Carotene; Carotenoids; Diet; Global Health; Head and Neck Neoplasms; Humans; Neoplasms, Experimental; Prospective Studies; Respiratory Tract Neoplasms; Retrospective Studies; Risk; Rodentia; Smoking; United States; Vitamin A

Topics: Alcohol Drinking; Animals; Anticarcinogenic Agents; beta Carotene; Carcinoma, Squamous Cell; Carotenoids; Cell Differentiation; Clinical Trials as Topic; Cricetinae; Diet; Drug Screening Assays, Antitumor; Head and Neck Neoplasms; Humans; Leukoplakia, Oral; Mesocricetus; Respiratory Tract Neoplasms; Smoking; United States; Vitamin A

We investigated whether the consumption of fruit and vegetables lowered cancer mortality in a cohort of 2112 Welsh men ages 45-69 years (The Caerphilly Study), which was followed-up for 13.8 years. At baseline (between 1979 and 1983), participants completed a 56-item food frequency questionnaire from which the consumption of fruit and vegetables was calculated. Relative risks (RR) were estimated with Cox proportional hazard analysis, with death from various types of cancer as a dependent variable, and fruit, vegetables, vitamin C, beta-carotene, dietary fiber, and potential confounders as independent variables. Mean consumption of vegetables and fruit at baseline was 118 g/day and 83 g/day, respectively. During follow-up 114 men died from cancer, including 51 men who died from respiratory tract cancer and 45 men who died from digestive tract cancer. Fruit consumption and the intake of dietary fiber were inversely related to respiratory tract cancer, but after adjustment for potential confounders including age, smoking, and social class, the association with fruit consumption became nonsignificant. Vegetable and fruit consumption was, independently from other risk factors, inversely related to mortality from cancer of the digestive tract (P for trend = 0.021), mainly due to an inverse association with fruit consumption (RR for the highest quartile versus the lowest was 0.3; 95% CI, 0.1-0.8). Vitamin C, beta-carotene, and dietary fiber were not significantly associated with cancers of the digestive tract. Vegetable and fruit consumption was also inversely related to all-cause cancer mortality, and the strongest association was observed for fruit consumption (RR in the highest versus lowest quartile was 0.5; 95% CI, 0.3-1.0). Consumption of vegetables and particularly the consumption of fruit could considerably lower the risk of dying from cancer in middle-aged men.

Topics: Age Factors; Antioxidants; Ascorbic Acid; beta Carotene; Cause of Death; Cohort Studies; Confounding Factors, Epidemiologic; Diet; Dietary Fiber; Digestive System Neoplasms; Feeding Behavior; Follow-Up Studies; Fruit; Humans; Longitudinal Studies; Male; Middle Aged; Neoplasms; Proportional Hazards Models; Respiratory Tract Neoplasms; Risk Factors; Smoking; Social Class; Vegetables; Wales

The effect of a high dietary level of beta-carotene on the formation of preneoplastic and neoplastic respiratory tract lesions was studied in hamsters intratracheally treated with benzo[a]pyrene (B[a]P) attached to ferric oxide (Fe2O3) and suspended in saline. In addition to conventional histopathological examinations, the expression of cytokeratins and the glutathione S-transferase isoenzyme Pi (GST-Pi) was determined in tracheal epithelium using immunocytochemical techniques. B[a]P treatment increased the expression of cytokeratins in tracheal mucous and ciliated epithelial cells as detected by antibody RCK102 (cytokeratins 5 and 8), which normally recognizes basal cells only. The expression of cytokeratins in mucous and ciliated cells as detected by antibody RGE53 (cytokeratin 18) was decreased by B[a]P treatment. Furthermore, the expression of the cytokeratin detected by antibody RKSE60 (cytokeratin 10), characteristic of metaplastic squamous cells, and the expression of the GST-Pi, characteristic of metaplastic changes, was increased in trachael epithelium of hamsters treated with B[a]P. There was no evidence for dietary beta-carotene affecting the expression of cytokeratins or GST-Pi. The incidence of preneoplastic changes and tumors of the respiratory tract was not reduced by dietary beta-carotene. On the contrary, the tumor response of the respiratory epithelium was almost twice as high in hamsters fed the high beta-carotene diet than in hamsters on the low beta-carotene diet. However, this difference was not statistically significant (P = 0.15); hence, the present study did not produce evidence for a clear effect of beta-carotene on B[a]P-induced respiratory tract cancer in hamsters.

Topics: Animals; Antineoplastic Agents; Benzo(a)pyrene; beta Carotene; Carotenoids; Cricetinae; Epithelium; Glutathione Transferase; Keratins; Male; Mesocricetus; Neoplasms, Experimental; Respiratory Tract Neoplasms; Trachea

The study described in this paper was primarily conducted to identify the cell types involved in the formation, progression and regression of metaplastic changes in the respiratory tract epithelium of hamsters after intratracheal intubations with benzo[a]pyrene. Furthermore, the role of vitamin A and beta-carotene in these processes was studied. In the course of the study a remarkable effect of dietary beta-carotene on survival of hamsters became a subject of investigation. Hamsters were fed diets with various levels of vitamin A or beta-carotene and were treated intratracheally with a suspension of benzo[a]pyrene with ferric oxide in saline. The tumour response of the respiratory tract was very low (2.8%) and hyper- and metaplasia of respiratory epithelium were virtually absent. However, an interesting observation was an exceptionally low mortality of only 2% after 69 weeks in the group of hamsters fed a high beta-carotene diet (1% w/w), whereas in the other groups mortality after 69 weeks amounted to 25%. Although the exact cause of death of most of the hamsters could not be established, a 40% reduction of lipid peroxidation in the livers was found in the high beta-carotene group. Moreover, in this group the degree and incidence of nephrosis and of focal mineralization of kidneys and heart were lower than in the other groups. These favourable effects of the high beta-carotene diet may have contributed to the unusually high survival rate in hamsters fed this diet. Further studies are planned to verify and study this observation.

Topics: Animals; Benzo(a)pyrene; beta Carotene; Carotenoids; Cricetinae; Diet; Eating; Epithelium; Ferric Compounds; Intubation, Intratracheal; Liver; Male; Mesocricetus; Metaplasia; Respiratory System; Respiratory Tract Neoplasms; Vitamin A

The modifying effect of beta-carotene on benzo[a]pyrene (BP)-induced tumors of the respiratory tract was investigated in Syrian hamsters. Groups of hamsters were fed a semisynthetic diet supplemented with either no or 56 mg/kg beta-carotene. Respiratory tract tumors were induced by intratracheal instillation of BP attached to ferric oxide. The beta-carotene and vitamin A contents of the liver were increased in the high beta-carotene group, but the serum beta-carotene levels were very low when compared with those commonly observed in humans. beta-Carotene supplementation did not affect the tumor response of the respiratory tract. Neither the incidence and severity of preneoplastic changes were influenced. However, there was a statistically significant inverse relationship between serum retinol content and the presence of respiratory tract tumors in survivors, regardless of the dietary treatment.

Topics: Animals; Benzo(a)pyrene; beta Carotene; Body Weight; Carotenoids; Cricetinae; Energy Intake; Mesocricetus; Respiratory Tract Neoplasms