Serum levels of beta-carotene, vitamin A, and zinc in male lung cancer cases and controls

Serum and tissue zinc in epithelial malignancies: a meta-analysis

BACKGROUND AND OBJECTIVES

Current studies give us inconsistent results regarding the association of neoplasms and zinc(II) serum and tissues concentrations. The results of to-date studies using meta-analysis are summarized in this paper.

METHODS

Web of Science (Science citation index expanded), PubMed (Medline), Embase and CENTRAL were searched. Articles were reviewed by two evaluators; quality was assessed by Newcastle-Ottawa scale; meta-analysis was performed including meta-regression and publication bias analysis.

RESULTS

Analysis was performed on 114 case control, cohort and cross-sectional studies of 22737 participants. Decreased serum zinc level was found in patients with lung (effect size = -1.04), head and neck (effect size = -1.43), breast (effect size = -0.93), liver (effect size = -2.29), stomach (effect size = -1.59), and prostate (effect size = -1.36) cancers; elevation was not proven in any tumor. More specific zinc patterns are evident at tissue level, showing increase in breast cancer tissue (effect size = 1.80) and decrease in prostatic (effect size = -3.90), liver (effect size = -8.26), lung (effect size = -3.12), and thyroid cancer (effect size = -2.84). The rest of the included tumors brought ambiguous results, both in serum and tissue zinc levels across the studies. The association between zinc level and stage or grade of tumor has not been revealed by meta-regression.

CONCLUSION

This study provides evidence on cancer-specific tissue zinc level alteration. Although serum zinc decrease was associated with most tumors mentioned herein, further--prospective--studies are needed.

Dietary zinc, copper and selenium, and risk of lung cancer

Zinc, copper and selenium are important cofactors for several enzymes that play a role in maintaining DNA integrity. However, limited epidemiologic research on these dietary trace metals and lung cancer risk is available. In an ongoing study of 1,676 incident lung cancer cases and 1,676 matched healthy controls, we studied the associations between dietary zinc, copper and selenium and lung cancer risk. Using multiple logistic regression analysis, the odds ratios (OR) and 95% confidence intervals (CI) of lung cancer for all subjects by increasing quartiles of dietary zinc intake were 1.0, 0.80 (0.65-0.99), 0.64 (0.51-0.81), 0.57 (0.42-0.75), respectively (p trend = 0.0004); similar results were found for men. For dietary copper, the ORs and 95% CI for all subjects were 1.0, 0.59 (0.49-0.73), 0.51 (0.41-0.64), 0.34 (0.26-0.45), respectively (p trend < 0.0001); similar reductions in risk and trend were observed by gender. Dietary selenium intake was not associated with risk, except for a significant inverse trend (p = 0.04) in men. Protective trends (p < 0.05) against lung cancer with increased dietary zinc intake were also found for all ages, BMI > 25, current smokers, pack-years < or =30, light drinkers and participants without emphysema. Increased dietary copper intake was associated with protective trends (p < 0.05) across all ages, BMI, smoking and vitamin/mineral supplement categories, pack-years < or =30 and 30.1-51.75 and participants without emphysema. Our results suggest that dietary zinc and copper intakes are associated with reduced risk of lung cancer. Given the known limitations of case-control studies, these findings must be interpreted with caution and warrant further investigation.

Correlation of serum retinol and its relation with lipid prolile in Indian cancer patients

The present study was undertaken to investigate the relation of retinol with lipid profile of patients with cancers of breast, stomach, oesophagus, colon, gallbladder, pancreas, lung and cervix. Serum retinol was assayed in 120 patients and 40 healthy normal control by reverse phase HPLC using CLC-ODS C-18 columns and retinyl acetate as an internal standard.Significant decease in serum cholesterol and LDL was observed in patients with cancers of esophagus, colon, stomach, pancreas and gallbladder respectively.Retinol was reduced in all forms of cancers but pronounced decrease was observed in oesophagus, gallbladder, pancreas, stomach and colon. Serum Retinol in all patients was directly correlated with total cholesterol and LDL. These findings suggest that therapeutic modalities of this vitamin could be planned for these patients, as vitamin A is known to act as an antioxidant for prevention of certain cancers.

Chemopreventive potential of fumaric acid, N-acetylcysteine, N-(4-hydroxyphenyl) retinamide and beta-carotene for tobacco-nitrosamine-induced lung tumors in A/J mice

Four agents, fumaric acid (FA), N-acetylcysteine (NAC), N-(4-hydroxyphenyl) retinamide (4-HPR) and beta-carotene (beta-CT), were evaluated for potential chemopreventive activity using the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumor model in female A/J mice. The agents were evaluated in both 16-week and 52-week bioassays at two dose levels corresponding to 0.8 maximum tolerated dose (MTD) and 0.4 MTD administered throughout the bioassay either in the diet (FA, 160 and 80 mmol/kg diet; NAC, 160 and 80 mmol/kg diet; 4-HPR, 4 and 2 mmol/kg diet) or by subcutaneous injection twice a week (beta-CT, 32 and 16 mg/kg b.w.). Mice were treated with a single i.p. dose of 10 micromol NNK in saline 1 week after administration of test agent. Lung adenomas were evaluated in the 16-week bioassay, whereas both adenomas and adenocarcinomas of the lung were determined in the 52-week bioassay. Both bioassays showed that all four agents did not significantly inhibit the total tumor incidence and multiplicity of the lung. However, the incidence of adenocarcinomas was reduced (P < 0.01) at 52 weeks in NNK groups given either 0.8 MTD NAC or 0.8 MTD beta-CT compared with the NNK control group. The decreases in adenocarcinomas were accompanied by corresponding increases in adenomas in these treatment groups. Thus, this study showed that FA, NAC, 4-HPR and beta-CT did not inhibit the total tumor formation, however, at the higher doses both NAC and beta-CT significantly retarded the malignant progression in the lung of NNK-treated A/J mice.

Oral and pharyngeal cancer, diet, smoking, alcohol, and serum vitamin A and beta-carotene levels: a case-control study in men

A case-control study was conducted in Melbourne, Australia. Forty-one men with histologically confirmed squamous cell oral or pharyngeal cancer were compared with 398 male community controls. A statistically significant increase in risk was found for alcohol (ethanol) consumption and for smoking, and there was a synergistic effect for these two exposures. Statistically significant protection was noted with increasing intake of dietary vitamin C, dietary beta-carotene, fruit, vegetables, and dietary fiber. The mean serum levels of beta-carotene and vitamin A were statistically significantly lower when the cases were compared with another set of 88 male controls of a similar age who were hospitalized for minor surgical operations. This study confirms a causal effect of smoking and alcohol and a protective role for a high dietary intake of fruit, vegetables, cereals, and, particularly, beta-carotene- and vitamin C-containing foods.

Environmental tobacco smoke: current assessment and future directions

Scientific information on environmental tobacco smoke (ETS) is critically reviewed. Key areas addressed are: differences in chemical composition between mainstream smoke, sidestream smoke, and ETS; techniques for measurement of ETS; epidemiology; in vitro and in vivo toxicology; and chamber and field studies of perceptual or physiological effects. Questions concerning estimation of ETS exposure, suitability of various biomarkers, calculation of lifetime dose, control of confounding variables, use of meta-analysis, and the relationship between ETS concentrations and human responses all emphasize the need for additional research in order to assess potential effects of ETS on health or comfort.

Diet, alcohol, smoking, serum beta-carotene, and vitamin A in male nonmelanocytic skin cancer patients and controls

A case-control study was conducted in Melbourne, Australia of 88 consecutive males admitted for the surgical removal of a nonmelanocytic skin cancer (histologically confirmed basal cell carcinoma and squamous cell carcinoma) and of 88 male control patients admitted for small elective surgical procedures. In both cases and controls, previous diet, alcohol consumption, and smoking habit were investigated and serum beta-carotene and vitamin A levels were measured. A statistically significant inverse relationship was found between the risk of skin cancer and a high intake of fish (p = 0.05); vegetables in general (p < 0.001); beans, lentils, or peas (p < 0.001), carrots, silverbeet (Swiss chard), or pumpkin (p < 0.001); cruciferous vegetables (cabbage, brussel sprouts, or broccoli) (p < 0.001); and beta-carotene- and vitamin C-containing foods (p = 0.004). Cases had a lower mean serum level of beta-carotene (p < 0.001) and vitamin A (p = 0.02) than controls. The incidence of skin cancer in the study was inversely related to the level of serum beta-carotene (p < 0.0001). The correlation coefficient between dietary beta-carotene/vitamin C and serum beta-carotene was 0.22 (p = 0.04). Smoking and alcohol consumption showed no statistically significant association with the risk of nonmelanocytic skin cancer. The results were similar for both cell types. A high intake of vegetables including cruciferous vegetables, beta-carotene- and vitamin C-containing foods, and fish appears to be protective for nonmelanocytic skin cancer, and this deserves further study, as does the possible etiologic relevance of the low serum levels of beta-carotene and vitamin A.

A case-control study of dietary carotene in men with lung cancer and in men with other epithelial cancers

Dietary carotene intake during the year before diagnosis was estimated for 96 men with lung cancer, 75 men with other epithelial cancers, and 97 hospital controls. Relative to those of men in the lowest third of carotene intake (less than 1,683 micrograms/day), the smoking-adjusted odds ratios for men in the middle (1,683-2,698 micrograms/day) and upper (greater than 2,698 micrograms/day) thirds of carotene intake were 0.67 and 0.45, respectively, for lung cancer (one-sided test for trend, p = 0.048) and 0.63 and 0.65, respectively, for other epithelial cancers (one-sided test for trend p = 0.074). The protective effect of estimated dietary carotene intake was considerably stronger than was the effect of total intake of carotene-rich vegetables and fruits (grams per day), providing some evidence that the protective factor is carotene itself rather than another component of vegetables and fruits.

Exposure to the carcinogen benzopyrene depletes tissue vitamin A: beta-carotene prevents depletion

Evidence in humans and laboratory animals supports a cancer-protective effect of vitamin A, but the mechanism remains unclear. While vitamin A deficiency causes squamous metaplasia, and lung cancer patients have lower vitamin A status, their serum vitamin A levels are not indicative of deficiency. We hypothesize that local enzymatic degradation of vitamin A can be induced by exposure to carcinogens such as benzopyrene found in cigarette smoke. This study was designed to determine if benzopyrene exposure depletes tissue vitamin A and whether beta-carotene might prevent the depletion. Weanling male Fischer rats were fed a nutritionally complete purified diet, supplemented with or without benzopyrene at 400 mg/kg feed or beta-carotene at 2 g/kg feed. Vitamin A content of the liver, small intestine, and serum was determined by high-performance liquid chromatography. There was no effect of benzopyrene feeding on serum retinol levels through four weeks. However, there was a decline in tissue retinol in the liver and small intestine by two weeks, with a 30% decline by four weeks (p less than 0.05). In rats fed beta-carotene, there was no effect of benzopyrene on tissue vitamin A level. These results indicate that exposure to benzopyrene induces a local tissue vitamin A depletion despite a vitamin A-sufficient diet and maintenance of serum vitamin A levels. A high intake of beta-carotene prevented the vitamin A depletion effect of benzopyrene exposure. Further studies appear warranted to determine whether some of the adverse effects of environmental carcinogens, as found in cigarette smoke, charcoal-broiled meats, and industrial wastes, might be alleviated by dietary intervention.

Vitamins and lung cancer

Several factors are known to promote the development of a lung cancer. Smoking, occupation, environment, chronic bronchitis, and scars in the lung are all risk factors. Many studies have stressed the importance of nutrition, in particular vitamins. Vitamin A is necessary for cell differentiation. Retrospective and prospective studies have proven the inverse relation between provitamin A, beta-carotene, and lung cancer of the squamous and oat cell types. Studies in which beta-carotene or natural vitamin A are supplied to smokers, controls, and patients after resection for lung cancer are in progress. The study of other vitamins such as vitamin C and vitamin E has not led to definitive conclusions. The trace element selenium may also exert a beneficial effect.