Dietary vitamin A and risk of cancer in the Western Electric study

Vitamins and lung cancer

Lung cancer is the most common cancer in the world, and smoking is the major risk factor, accounting for about 90% of the cases. Diet has also been implicated in the development of lung cancer, although the specific nutrients remain to be elucidated. Vitamins with antioxidant activity have received much attention. beta-Carotene, the most efficient provitamin A, was found to be inversely related to the risk of lung cancer in many prospective epidemiological studies, especially in studies measuring serum concentrations of beta-carotene. The findings from controlled trials, however, contradict the hypothesis that beta-carotene could prevent lung cancer, but rather suggest increased risk of lung cancer with supplementary beta-carotene. Data from both prospective studies and a controlled trial suggest no role for vitamin E in lung carcinogenesis. Some prospective epidemiological studies suggest an inverse relationship between dietary vitamin C and the risk of lung cancer, but due to the high correlation between dietary vitamin C and vegetable and fruit intake the independent role of dietary vitamin C is difficult to estimate. Studies using prediagnostic plasma concentrations of ascorbic acid do not support the involvement of vitamin C in lung carcinogenesis, and no controlled trials of vitamin C on lung cancer have been published. Thus, supplementation with antioxidant vitamins cannot be recommended for the prevention of lung cancer. Non-smoking is the most important target in the prevention of lung cancer. High intakes of vegetables and fruits may provide additional protection and are unlikely to be harmful.

Beta - caroteno e câncer

Há mais de vinte anos tem-se pesquisado sobre a relação entre β-caroteno e câncer. Inúmeros trabalhos têm tentado esclarecer a hipótese, formulada a partir de achados epidemiológicos e experimentais, de que o carotenóide poderia agir como anticarcinogênico de origem alimentar. Estudos epidemiológicos observacionais, tipo caso-controle e coorte, sugerem que o consumo elevado de frutas e vegetais ricos em β-caroteno reduz o risco de câncer, especialmente de pulmão. Estudos de intervenção em humanos, administrando doses farmacológicas crônicas a milhares de indivíduos, têm demonstrado resultados contraditórios. Pesquisas em animais experimentais e em cultura de células apontam o carotenóide como quimiopreventivo, agindo sobretudo como retinóides, através de conversão metabólica extra-intestinal e como antioxidante de membrana. Conclui-se que o β-caroteno pode proteger contra o câncer, quando suplementado em doses fisiológicas, isto é, cerca de 4 a 6mg/dia. Doses farmacológicas crônicas não estão recomendadas para indivíduos saudáveis e particularmente para tabagistas.

Association between diet and lung cancer location

Lung cancers occur more commonly in the upper lobes than in the lower lobes, but its pathophysiologic basis is not well understood. Because numerous studies have reported a consistent inverse relationship between lung cancer risk and intake of certain vegetables and fruits, we hypothesized that the balance between diet-derived protective substances delivered via the circulation and cigarette-derived carcinogenic substances delivered via the airways would be less favorable in the upper lobes compared with the lower lobes, hence accounting for the upper lobe predominance of tumors among smokers. Thus, we examined the association between diet and tumor location in 328 patients with lung cancer. The ratio of upper to lower lobe tumors was 2.5:1.0. In univariate analysis, age, height, weight, sex, race, family history of cancer, education level, tumor histology, calories consumed per day, and intake of animal fat did not differ significantly between patients with upper versus lower lobe tumors. Predictors of tumor location in univariate analysis were family history of lung cancer; smoking history; history of asbestos exposure; and intakes of yellow-orange vegetables, alpha-carotene, beta-carotene, and vitamins A, C, and E. In multivariable logistic regression analysis, the independent predictors of upper lobe tumor location were family history of lung cancer (p = 0.03), history of asbestos exposure (p = 0.02), less intake of yellow-orange vegetables (p < 0.04), and less intake of vitamin E (p = 0.05). Our results show a strong inverse association between upper lobe location of lung cancer and intake of yellow-orange vegetables and vitamin E.

Association of cigarette smoking and asbestos exposure with location and histology of lung cancer

Prior studies have suggested that lung cancers that arise in association with cigarette smoking favor an upper-lobe location while those associated with asbestos exposure favor a lower-lobe location. An excess of adenocarcinomas has also been reported among cases not exposed to cigarette smoke as well as among those exposed to asbestos. However, these studies typically have not adjusted adequately for potential confounders such as the patient's age, sex, race, or family history of cancer. To better examine the effects of cigarette smoking and asbestos exposure on location and histology of lung cancer, we analyzed data from a large case-control study that included 456 patients with stage I or II lung cancer. Patients with upper-lobe tumors tended to have had more exposure to tobacco as assessed by pack-years smoked (54.7 versus 46.2, p = 0.07) and less time since quitting smoking (3.0 versus 5.5 yr, p = 0.05). In contrast to some prior reports, asbestos exposure was also associated with an upper-lobe location of tumor. Among those with upper-lobe tumors, 14.6% had a history of significant asbestos exposure compared with 5.4% of those with lower-lobe tumors (p < 0.01). The relationship between asbestos exposure and upper-lobe location of tumor was also statistically significant whether stratified by smoking or analyzed by multivariable logistic regression modeling. Adenocarcinomas were more likely among those with less exposure to cigarette smoke based on fewer pack-years smoked (41.5 versus 61.8, p = 0.0001) and more time since quitting smoking (5.0 versus 3.0 yr, p = 0.02). The proportion of patients with significant exposure to asbestos was lower among those with adenocarcinomas but was not statistically significant (9.5 versus 15.3%, p = 0.09). In multivariable logistic regression analysis, longer time since smoking exposure remained a significant predictor of adenocarcinomas (p < 0.02), but history of asbestos exposure did not predict tumor histology. Thus, in patients with lung cancer, both cigarette smoking and asbestos exposure histories favor an upper-lobe location of tumor. Longer time since smoking exposure favors adenocarcinomas, but the history of asbestos exposure does not appear to influence the tumor histology.

Effects of resistant starch- and vitamin A-supplemented diets on the promotion of precursor lesions of colon cancer in rats

We have evaluated the potential protective effect of resistant starch (RS)- and vitamin A-supplemented diets on the promotion of preneoplasic lesions of rat colon, aberrant crypt foci (ACF), induced by 1,2-dimethylhydrazine dihydrochloride (DMH). We have tried to show whether the association of these two dietary constituents in the same diet could have synergistic effects. RS, vitamin A, and RS+ vitamin A were incorporated into the rat diets. Experimental diets were given one week after DMH injection and maintained for 12 weeks until the animals were sacrificed. The total number of ACF decreased with the three experimental diets. For RS- and RS + vitamin A-supplemented diets, this decrease is primarily due to a decrease in small ACF. For the vitamin A-supplemented diet, small and large ACF have a tendency to decrease. The effects of the diets on parameters influencing colon carcinogenesis were also studied. Only RS- and RS + vitamin A-supplemented diets have modified cecal pH, fecal and cecal butyrate contents, fecal excretion, cecal weight, and colon length. Vitamin A has been observed in colonic epithelial cells of rats receiving vitamin A- and RS+ vitamin A-supplemented diets. The association between RS and vitamin A shows neither a cumulative nor a synergistic protective effect.

Diet and lung cancer 20+ years later: more questions than answers?

A critical review of epidemiological studies on diet and lung cancer over the last 20+ years has not provided overwhelming evidence that higher consumption of vegetables, fruit, low-fat/low-cholesterol foods or such micronutrients as carotenoids, selenium and vitamins A, C or E is associated with reduced lung cancer risk. Results from case-control studies have been more positive, with about one half showing fruit and vegetables or their associated micronutrients to be associated with reduced risk. However, most results from cohort and serum micronutrient studies, which avoid the problems of inaccurate accounting of diet and recall bias, were statistically insignificant. Moreover, although most studies were conducted on white male smokers in North America and Europe, the few studies which found significant contrary trends were among subjects of different backgrounds, i.e., black American males and Chinese women in China. Since male smokers vs. nonsmokers in Europe, North America and Japan have been shown in other studies to be lower consumers of fruit/vegetables, and less likely to pursue "perceived healthier lifestyles," the possibility that some of the epidemiological findings on diet and lung cancer are artifactually due to inadequate adjustment for behavioral correlates of smoking and health seekers in a particular society must be considered. This is especially true with recent chemoprevention trials showing higher lung cancer incidence and deaths among consumers of beta-carotene supplements vs. placebo.

Time course evaluation of carotenoid and retinol concentrations in posthatch chick tissue

Carotenoid and retinol concentrations were determined in chicks hatched from carotenoid-enriched eggs while being fed a carotenoid free starter diet. Single Comb White Leghorn (SCWL) hatching eggs were obtained from breeder hens fed diets enriched with either 0.2% beta-carotene, canthaxanthin, lutein, or basal control. Twenty-five day-old chicks hatched from each treatment group were placed in a battery and fed a carotenoid-free basal diet. At 1, 4, 7, 10, and 13 d, five chicks per treatment were randomly selected, and blood serum, liver, and unabsorbed yolk sac were collected for carotenoid and retinol analysis. There were no significant differences in retinol concentrations in the serum, liver, and unabsorbed yolk sac of the chickens. Only small amounts of beta-carotene were detected in the chick tissues. Concentration of all three carotenoids and retinol were greater in the liver and unabsorbed yolk sac than in serum. In the serum and liver, respective carotenoid concentrations decreased and retinol concentration increased with increasing age, whereas respective carotenoid and retinol concentrations in the unabsorbed yolk sac increased over time. It may be concluded that yolk sac carotenoids are not absorbed well, as unabsorbed yolk sac concentrations increased over time, and that carotenoid in serum and liver decrease linearly with increasing age.

Influence of benzylisothiocyanate and 13-cis-retinoic acid on micronucleus formation induced by benzo[a]pyrene

The purpose of this study was to investigate the influence of benzylisothiocyanate (BIT) and 13-cis-retinoic acid (RA) upon the genotoxic potential of benzo[a]pyrene (BaP) to induce micronucleus formation in the bone marrow of mice. Eighty-two male mice were divided into 10 groups. One group served as a negative control (olive oil intubation). Four groups received an oral intubation of various concentrations of BIT (15 to 120 mg/kg) and i.p. injections of BaP (185 mg/kg). Another four groups were treated identically, but received RA (20 to 150 mg/kg) in place of BIT. Finally, one group received only i.p. injection of BaP (185 mg/kg). The results showed that both BIT and RA significantly reduced the frequency of micronucleus formation in the bone marrow of the BaP treated animals. BIT was found to be effective at all the tested concentrations. RA was effective only at three of the four tested concentrations (40, 75 and 150 mg/kg). These findings indicate that both BIT and RA may reduce the genotoxic effects of benzo[a]pyrene in the mice under the test conditions utilized.

Clinical studies in head and neck cancer chemoprevention

Secondary neoplasms represent a major threat for patients with head and neck cancer. The prevention of secondary neoplasms has been a major goal of head and neck cancer chemoprevention efforts. In order to help develop effective strategies, reversal of oral premalignancy has been used as a model for chemoprevention. There is now sufficient data to show the chemopreventive effect in premalignant lesions of some natural compounds and their derivatives. Retinoids are the most studied chemopreventive agents for the treatment of oral leukoplakia. Other compounds with chemopreventive activity are carotenoids, Vitamin E derivatives and Selenium. There are two large prospective, randomized, chemoprevention clinical trials, one in Europe and the other in North America, using prevention of secondary malignancy as the primary study end-point. Until these trials are completed, the use of chemoprevention in head and neck cancer should be limited to clinical trials.

Retinoid receptors in human lung cancer and breast cancer

Retinoids, the natural and synthetic vitamin A derivatives, are known to inhibit the proliferation of lung cancer and breast cancer cells and the growth of carcinogen-induced bronchogenic squamous cell carcinoma and mammary tumors, and have been used as chemoprevention agents against both types of cancer. However, clinical trials of retinoids in patients with advanced lung cancer and breast cancer have not been successful. In studying how retinoid sensitivity is lost in cancer cells, we have found that lack of the retinoic acid receptor beta (RAR beta) gene expression and its abnormal regulation by retinoic acid (RA) are common features in human lung cancer and breast cancer cells. The absence and abnormal RA regulation of RAR beta correlates with the loss of anti-proliferation effect of RA in hormone-independent breast cancer cells, and is due to different abnormalities found in cancer cells. Furthermore, expression of RAR beta gene in hormone-independent breast cancer cells restores their RA sensitivity. These data demonstrate that RAR beta can mediate the growth inhibitory effect of RA and suggest that the lack of RAR beta may contribute to retinoid resistance in certain cancer cells.

Nutrition and lung cancer

Epidemiologic evidence on the relationship between nutrition and lung cancer is reviewed. Observational studies of diet and lung cancer, both prospective and retrospective, continue to suggest strongly that increased vegetable and fruit intake is associated with reduced risk in men and women; in various countries; in smokers, ex-smokers, and never-smokers; and for all histologic types of lung cancer. Prospective studies of blood beta-carotene levels, arguably the best available biomarker of vegetable and fruit intake, indicate that low levels are predictive of increased lung cancer incidence. However, in a randomized, placebo-controlled clinical trial in male smokers, lung cancer incidence and total mortality were increased significantly among the men receiving beta-carotene supplements. If beta-carotene can prevent lung carcinogenesis, which the trial cannot rule out, then the dosage, duration of use, method of administration, and/or subpopulation are critical. Ongoing clinical trials, some of which include women, will provide much-needed information. Other carotenoids, other phytochemicals, and associated dietary patterns may explain the beneficial effects of vegetables and fruits and have not been explored adequately in epidemiologic work. Several observational epidemiologic studies, both prospective and retrospective, have indicated that diets high in fat, saturated fat, and cholesterol may increase the risk of lung cancer and that the effect is not mediated through vegetable and fruit intake. The relationship, although not yet established, merits further investigation. Since beta-carotene can function as an antioxidant, other micronutrients with this potential, specifically vitamins E and C and selenium, also have been proposed to reduce lung cancer risk. However, the totality of the epidemiologic evidence is not, at present, persuasive for any one of these micronutrients.

New chemotherapy agents in the treatment of advanced non-small cell lung cancer: an update including data from the Seventh World Conference on Lung Cancer

Over the past two decades, modest gains have been made in chemotherapy for non-small cell lung cancer with the addition of cisplatin-based regimens to the therapeutic armamentarium. Over the last decade, several new agents with significant activity have reached the level of Phase II and III testing. This list of new drugs includes: navelbine, the taxanes--taxol and taxotere, gemcitabine, edatrexate and the camptothecins--irinotecan and topotecan. During this period, oral etoposide and epirubicin were re-investigated and biological agents such as the retinoids, interferons and interleukins were also explored as alternatives to traditional chemotherapy. As these new drug investigations proceeded, basic scientists made important discoveries which are now beginning to be applied to therapy. The future promises to combine these active new drugs with therapies directed against targets unique to non-small cell lung cancer cells.

Neonatal immune response and growth performance of chicks hatched from single comb White Leghorn breeders fed diets supplemented with beta-carotene, canthaxanthin, or lutein

Forty Single Comb White Leghorn (SCWL) hens and 8 SCWL cocks were randomly divided into four treatment groups. Each group was fed a diet containing .02% beta-carotene, canthaxanthin, lutein, or basal control. After 20 d of feeding, eggs were collected daily from each experimental group for incubation. Two different hatches were set and chicks from each hatch were used for one of two different experiments. In both experiments, 24 chicks per treatment were vaccinated against Newcastle disease virus at 1 d of age and raised for 5 wk on a basal diet. In the second experiment, birds were revaccinated at 3 wk of age. In both experiments, at the end of 5 wk birds were killed and bursa of Fabricius, liver, and spleen were collected. For both experiments, there were no differences in antibody titers, weight gain, feed conversion ratio, and relative bursa weights of chicks. However in the second experiment, birds hatched from breeders fed lutein had significantly lower relative liver weights than chicks of the other treatments, whereas birds hatched from the breeders fed beta-carotene and canthaxanthin had significantly lower spleen weights than the control. These experiments suggest that carotenoids may not be effective in increasing neonatal immune response when they supplement practical breeder diets.

beta-carotene and cancer chemoprevention

Evidence supports the potential role of beta-carotene in cancer prevention. Basic research has demonstrated that beta-carotene can trap organic free radicals and/or deactivate excited oxygen molecules which may have an anticancer effect by preventing tissue damage. Although observational epidemiologic studies are not entirely consistent, many show an inverse association between dietary intake or blood levels of beta-carotene and subsequent cancer risk. Two large-scale randomized trials of beta-carotene have been completed. A Finnish trial demonstrated no benefit of beta-carotene among middle-aged male smokers, with those assigned to this supplement in fact experiencing an increased risk of lung cancer. However, because of the long latency period for cancer, which may be a decade or more, the six-year duration of treatment in this trial may have been inadequate to detect an anticancer effect. A Chinese trial demonstrated a modest reduction in cancer mortality from a combined regimen of beta-carotene, vitamin E, and selenium. The effect of the individual agents could not be assessed, and because the trial was carried out among a nutritionally deficient population, its results may not have direct relevance to well-nourished individuals. Several additional large-scale trials of beta-carotene are ongoing. The Physicians' Health Study, which is testing beta-carotene among 22,071 US male physicians, will have an average duration of treatment of 12.5 years at its scheduled termination in late 1995. Data in women will be available from the Women's Health Study, which began in 1992, and will randomize approximately 40,000 US female health professionals.(ABSTRACT TRUNCATED AT 250 WORDS)

Antioxidants and carcinogenesis

It is established beyond doubt that free radicals in tissues and cells can damage DNA, proteins, carbohydrates and lipids. These potentially deleterious reactions are at least partly controlled by antioxidants capable of scavenging free radicals. It is widely believed that a proper balance between free radicals and antioxidants is essential for the health of an organism. A vast body of observational epidemiological studies has suggested that high intake of dietary or supplemental antioxidants protects against ischaemic heart disease, various types of cancer and several other diseases. Final proof for the beneficial effects of antioxidants can, however, be obtained from controlled studies. Conflicting results of the first three major clinical trials force us to postpone conclusions of the usefulness of antioxidant supplements in disease prevention until the other on-going trials have been published.

The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers

BACKGROUND

Epidemiologic evidence indicates that diets high in carotenoid-rich fruits and vegetables, as well as high serum levels of vitamin E (alpha-tocopherol) and beta carotene, are associated with a reduced risk of lung cancer.

METHODS

We performed a randomized, double-blind, placebo-controlled primary-prevention trial to determine whether daily supplementation with alpha-tocopherol, beta carotene, or both would reduce the incidence of lung cancer and other cancers. A total of 29,133 male smokers 50 to 69 years of age from southwestern Finland were randomly assigned to one of four regimens: alpha-tocopherol (50 mg per day) alone, beta carotene (20 mg per day) alone, both alpha-tocopherol and beta carotene, or placebo. Follow-up continued for five to eight years.

RESULTS

Among the 876 new cases of lung cancer diagnosed during the trial, no reduction in incidence was observed among the men who received alpha-tocopherol (change in incidence as compared with those who did not, -2 percent; 95 percent confidence interval, -14 to 12 percent). Unexpectedly, we observed a higher incidence of lung cancer among the men who received beta carotene than among those who did not (change in incidence, 18 percent; 95 percent confidence interval, 3 to 36 percent). We found no evidence of an interaction between alpha-tocopherol and beta carotene with respect to the incidence of lung cancer. Fewer cases of prostate cancer were diagnosed among those who received alpha-tocopherol than among those who did not. Beta carotene had little or no effect on the incidence of cancer other than lung cancer. Alpha-tocopherol had no apparent effect on total mortality, although more deaths from hemorrhagic stroke were observed among the men who received this supplement than among those who did not. Total mortality was 8 percent higher (95 percent confidence interval, 1 to 16 percent) among the participants who received beta carotene than among those who did not, primarily because there were more deaths from lung cancer and ischemic heart disease.

CONCLUSIONS

We found no reduction in the incidence of lung cancer among male smokers after five to eight years of dietary supplementation with alpha-tocopherol or beta carotene. In fact, this trial raises the possibility that these supplements may actually have harmful as well as beneficial effects.

Biology and chemoprevention of head and neck cancer

Head and neck cancer remains a common cause of mortality and morbidity in the United States and throughout the world. In spite of advances in the management of patients with advanced disease, overall survival in this group remains poor. Furthermore, although cancer mortality is lower in patients with early-stage disease, treatment results in significant morbidity, and these patients also face the risk of developing a second primary tumor. Chemoprevention is an innovative approach to decrease overall cancer morbidity and mortality using substances that are capable of preventing cancer progression. Head and neck cancer is an excellent model for chemoprevention, as its biology is consistent with the two concepts important for the development of chemoprevention strategies: field cancerization and multistep carcinogenesis. Several classes of compounds have been evaluated in chemoprevention trials. The most frequently studied agents, the retinoids, were found frequently to induce remissions in patients with oral leukoplakia. Furthermore, retinoids prevented progression to malignancy in one randomized maintenance study. Other agents, including beta-carotene and vitamin E, have been found also to have activity in the management of oral leukoplakia. However, the clinical role of chemopreventive agents in reducing cancer mortality remains to be defined. Two studies, one in head and neck cancer and one in lung cancer, have shown the ability of retinoids to prevent the development of second primary tumors. Current large randomized trials are defining the effectiveness of these agents in reducing the mortality of aerodigestive tract tumors in individuals at high risk.

The alpha-tocopherol, beta-carotene lung cancer prevention study: design, methods, participant characteristics, and compliance. The ATBC Cancer Prevention Study Group

The Alpha-Tocopherol, Beta-Carotene (ATBC) Lung Cancer Prevention Study was a randomized, double-blind, placebo-controlled, 2 x 2 factorial design, primary prevention trial testing the hypothesis that alpha-tocopherol (50 mg/day) and beta-carotene (20 mg/day) supplements reduce the incidence of lung cancer and possibly other cancers. Total and disease-specific mortality and incidence of various diseases and symptoms were monitored for safety. Between 1985 and 1993, 29,133 eligible male smokers aged 50 to 69 years at entry were randomized to receive daily active supplements or placebo capsules for 5 to 8 years (median 6.1 years), accumulating 169,751 follow-up years. This report describes the study design, methods, and protocol as well as the baseline characteristics and capsule compliance of the participants. The ATBC Study is the largest lung cancer chemoprevention trial conducted to date.

Retinoic acid suppresses human papillomavirus type 16 (HPV16)-mediated transformation of human keratinocytes and inhibits the expression of the HPV16 oncogenes

We have used a model system of normal HKc and HKc immortalized by transfection with HPV16 DNA (HKc/HPV16) to investigate the effect of RA on the growth of HKc/HPV16 and the expression of the HPV16 oncogenes E6 and E7. These studies found that HKc/HPV16 are about 100-fold more sensitive than normal HKc to growth inhibition by RA in both clonal and mass culture growth assays. The precursor to RA, retinol, was also found to be a more potent inhibitor of growth of HKc/HPV16 than normal HKc while beta-carotene did not inhibit growth of either normal HKc or HKc/HPV16. No differences were observed in the rate of uptake of [3H]RA or [3H]retinol between normal HKc and HKc/HPV16. Northern blot analysis of mRNA extracted from HKc/HPV16 cultured in the absence or in the presence of 10(-7) M RA showed that the expression of the HPV16 oncogenes E6 and E7 as well as the early ORFs E2 and E5 is substantially reduced following RA treatment. In addition, protein levels of E6 and E7, as measured by immunofluorescence (E6 and E7) and Western blot (E7) are also decreased by RA treatment of HKc/HPV16. Since E6 and E7 are considered the oncogenes of HPV16, we explored the possibility that RA may interfere with HPV16-mediated immortalization of HKc. The RA treatment (1 nM) of normal HKc, during or immediately following transfection with HPV16 DNA, inhibited immortalization by about 95%. Overall, these results provide a direct biochemical basis for a role of dietary retinoids in the chemoprevention of HPV-induced cancers.

Critical reappraisal of vitamins and trace minerals in nutritional support of cancer patients

The potential of a high intake of fresh fruits and vegetables in cancer prevention is well established. Epidemiological studies support carotene, vitamins A, C, E and selenium as the active compounds. Antioxidant properties and direct effects (e.g. inhibition of N-nitrosamine formation or cell-to-cell interactions) are invoked. The role of other trace elements is less clear. The modulation of immune function by vitamins and trace elements remains important and affects survival. In established cancers, the site-specific differences in the diet/cancer relation require appropriate dietary changes, e.g. low fat (20% by energy) in breast cancer, or high vegetable or fruit intake in lung cancer. Single high-dose supplements (e.g. vitamin C) have proved to have no curative or life-prolonging effect. Chemotherapy and radiation increase the requirements for antioxidant compounds. Supplementation can diminish the damage induced by peroxidation. Carefully planned and monitored trials that establish the optimal intake of micronutrients as adjuvants in cancer patients are required.

Diet and dermatology. The role of dietary manipulation in the prevention and treatment of cutaneous disorders

The role of dietary manipulation and vitamins in the prevention and treatment of certain skin diseases is reviewed. Manipulation of nutrition by either diet restriction or supplementation can effect cutaneous disorders such as skin cancer, wound healing, atopic dermatitis, psoriasis, and dermatitis herpetiformis.

Red blood cell folate is associated with the development of dysplasia and cancer in ulcerative colitis

Patients with extensive ulcerative colitis have a high risk of developing colon cancer. The etiology of mucosal dysplasia, a premalignant lesion that is used as a screening test in surveillance programs, is unknown. Previously, a case-control study [Lashner et al. (1989) Gastroenterology 97:255-259] suggested that folate supplementation was associated with a 62% reduction in the risk of developing dysplasia or cancer. The current case-control study was performed to obtain a better definition of this risk. All 67 patients with chronic ulcerative pancolitis having surveillance colonoscopy during a 1-year period were entered. There were 6 cases (4 with dysplasia and 2 with cancer) and 61 controls (no cancer or dysplasia). Red blood cell folate, reflecting intermediate-term stores, was a mean of 66.2 ng/ml lower in cases compared to controls. Serum folate, reflecting short-term stores, was not different between groups. Adjusting for confounding effects of age, sex, race, disease duration, and folate supplementation, the risk of dysplasia or cancer was significantly decreased by 18% for each 10 ng/ml increase in red blood cell folate (odds ratio 0.82, 95% confidence interval 0.68-0.99). Vitamins A, D, and E and carotene were lower in cases than in controls, but no water-soluble vitamin other than red blood cell folate was associated with an increased cancer risk. Depressed red blood cell folate is associated with an increased risk of dysplasia and cancer in patients with ulcerative colitis and may be a risk factor for neoplastic transformation.

Race and sex differences in associations of vegetables, fruits, and carotenoids with lung cancer risk in New Jersey (United States)

We used data from a case-control study conducted in New Jersey between 1980 and 1983 to evaluate race and sex differences in associations of vegetable, fruit, and carotenoid consumption with lung cancer. Cases included 736 White males, 860 White females, 269 Black males, and 86 Black females with incident, histologically confirmed, primary cancer of the trachea, bronchus, or lung. Controls were identified through drivers' license and Health Care Financing Administration files and included 548 White males, 473 White females, 170 Black males, and 47 Black females. Usual intakes of vegetables (predominantly yellow/green) and fruit (predominantly yellow/orange) as well as other food sources of carotenoids were ascertained by a food frequency questionnaire. White females showed significant inverse associations of lung cancer with vegetables, fruit, and carotenoids. White males showed nonsignificant inverse associations with vegetables and carotenoids, and Black females just with vegetables. No inverse associations were found for Black males. Vegetable consumption was associated with risk of all histologic types of lung cancer, but the pattern of increasing risk with decreasing intake was limited to smokers. We infer that consumption of yellow/green vegetables and carotenoids may confer protection from lung cancer to White male and White female smokers. Further studies are needed to clarify the effect in Blacks.

Carotenoid content of fruits and vegetables: an evaluation of analytic data

The test of the association between dietary intake of specific carotenoids and disease incidence requires the availability of accurate and current food composition data for individual carotenoids. To generate a carotenoid database, an artificial intelligence system was developed to evaluate data for carotenoid content of food in five general categories, namely, number of samples, analytic method, sample handling, sampling plan, and analytic quality control. Within these categories, criteria have been created to rate analytic data for beta-carotene, alpha-carotene, lutein, lycopene, and beta-cryptoxanthin in fruits and vegetables. These carotenoids are also found in human blood. Following the evaluation of data, acceptable values for each carotenoid in the foods were combined to generate a database of 120 foods. The database includes the food description; median, minimum, and maximum values for the specific carotenoids in each food; the number of acceptable values and their references; and a confidence code, which is an indicator of the reliability of a specific carotenoid value for a food. The carotenoid database can be used to estimate the intake of specific carotenoids in order to examine the association between dietary carotenoids and disease incidence.

The development and application of a carotenoid database for fruits, vegetables, and selected multicomponent foods

A carotenoid database for individual and multicomponent foods has been compiled that contains values for the five most common carotenoids (alpha-carotene, beta-carotene, beta-cryptoxanthin, lycopene, lutein) in 2,458 fruits, vegetables, and multicomponent foods containing fruits and vegetables. The database was used to estimate intakes of specific carotenoids for 19- to 50-year-old women (n = 1,102), using food consumption data obtained from dietary recalls in the US Department of Agriculture Continuing Survey of Food Intake by Individuals, 1986. The major contributors of alpha-carotene were carrots consumed as a single food or as an ingredient in multicomponent foods. Carrots, cantaloupe, and broccoli were the main sources of beta-carotene. Orange juices and blends, oranges, and tangerines were important contributors of beta-cryptoxanthin. Tomatoes and tomato products consumed as single foods or as ingredients in multicomponent foods provided most of the dietary lycopene. Contributors of lutein + zeaxanthin included collard, mustard, or turnip greens; spinach; and broccoli. The per capita consumption of total carotenoids (the sum of the five specific carotenoids) among these women was approximately 6 mg/day.

Lung cancer: a prospective study of smoking, occupation, and nutrient intake

A cohort study of lung cancer was conducted among 7,961 Japanese-American men who were interviewed and examined during 1965-1968. Information was collected about their smoking history, occupation, and nutrient intake. After 22 y, 227 incident cases of lung cancer were identified. Cigarette smoking significantly increased lung cancer risk. The relative risk (RR) was 3.1 for past smokers and 11.4 for current smokers, compared with never smokers. We separated lung cancer cases according to histological type, and it was found that current smokers had a RRs of 16.0 for squamous/small-cell carcinoma and 6.8 for adenocarcinoma of the lung. Unskilled manual workers had a significantly higher risk (RR = 1.5; 95% confidence interval, 1.1-2.2) for lung cancer than workers who were engaged in nonmanual occupations. There was no association between lung cancer and the 24-h intake of total calories, protein, fat, dietary cholesterol, carbohydrates, and alcohol, but this may have resulted from the limitations of a 24-h dietary questionnaire.

The etiology of lung cancer

The association between tobacco smoking and lung cancer has been noted for more than 50 years and continues to dominate the etiologic milieu of this malignant disease. Other agents, many discovered in the occupational setting, have also been substantiated as lung carcinogens. Inherent predisposition to the disease has long been suspected, and recent investigations suggest several potential mechanisms and a possible mode of inheritance. Considerable progress has been made in deciphiring the molecular defects present in lung cancer cells. These recent findings have been incorporated into two well-known models of lung carcinogenesis. As the details of the carcinogenic process are unraveled, one goal is to identify intermediate (preneoplastic) markers of exposure and inherent predisposition that will help assess the risk of lung cancer for individuals as well as for groups.

Antiproliferative effects of interferons -alpha and -beta in combination with 5-fluorouracil, cisplatin, and cis- and trans-retinoic acid in three human lung carcinoma cell lines

We assessed the antiproliferative effect of human recombinant interferon -alpha (IFN-alpha) or -beta in combination with 5-fluorouracil (5-FU), cisplatin, or cis- or trans-retinoic acid on two human nonsmall cell lung carcinoma cell lines (SK-LU-1 and SK-MES-1) and on one human small cell lung carcinoma cell line (NCI-H69). Results were obtained by direct cell count and/or by the clonigenic assay. The three cell lines differed in their sensitivities to the antiproliferative effects of the different agents. However, both NSCLC cell lines were more responsive to IFN-beta than to IFN-alpha. The SK-MES cell line was more resistant to both IFNs than the SK-LU-1. The NCI-H69 cells were resistant to all the drugs tested, except trans-retinoic acid. The dose and time of exposure were found to be important factors in the case of IFNs and cytotoxic agents, with lower surviving fractions obtained with the higher doses and longer exposures. This finding, however, did not hold true for the retinoic acids, which showed no antiproliferative effect. Within the sensitivity of our system, we did not identify any synergistic interaction in any of the cell lines with IFN-alpha or IFN-beta and 5-FU or cisplatin. A slight synergistic interaction was observed with IFN and cis- or trans-retinoic acid in the SK-LU-1 cell line which was not thought to be clinically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary factors related to colorectal neoplasms

Although the etiology of colorectal cancer is multifactorial, experimental evidence suggests a role for dietary factors in the promotion of this disease. The complex interrelations governing energy balance and the consumption of fat, fiber, and micronutrients make it difficult to define the precise role of specific dietary factors in the etiology of colorectal neoplasms. Epidemiologic studies have demonstrated a correlation between the prevalence of colorectal cancer and per capita consumption of meat and fat. Case-control studies investigating the relation between colorectal cancer and dietary fat consumption have yielded inconsistent results. Prospective studies have failed to demonstrate a relation between fat consumption and subsequent risk for colorectal cancer. There is an inverse correlation between fiber intake and the prevalence of colorectal carcinoma. A more detailed analysis of the influence of various types of dietary fiber on the subsequent risk for colorectal cancer will provide a better understanding of this relation. Fiber derived from fruits and vegetables may provide more effective protection than cereal fibers. Correlational studies have established an association between total caloric intake and the prevalence of colorectal carcinoma. The design of future studies investigating the influence of individual dietary constituents on the risk for colorectal cancer must control for variations in energy balance as a confounding variable. Recent evidence suggests that a variety of micronutrients, including calcium, vitamin D, selenium, and vitamins A, C, and E, exert an anticarcinogenic effect. Studies designed to evaluate the influence of alcohol consumption on colorectal carcinogenesis have yielded inconclusive results. The potential influence of food preparation methods on colorectal carcinogenesis requires further evaluation. There is no conclusive evidence to support any of the hypotheses proposed to explain the role of dietary factors in colorectal carcinogenesis. Intervention trials designed to monitor intermediate markers for colorectal cancer such as increased epithelial-cell proliferation rates and the development of aberrant crypt architecture provide the opportunity for testing these hypotheses in relatively short-term studies. The results from such studies can be utilized in the design of large-scale, long-term prospective studies to evaluate the influence of dietary factors on the development of colorectal neoplasms. These trials should generate the information required to develop strategies for diet modification to reduce the incidence of colorectal carcinoma.

Development of chemopreventive agents for lung and upper aerodigestive tract cancers

The lung and upper aerodigestive tract (oral cavity, larynx, pharynx, upper esophagus) will harbor the greatest proportion (approximately 20%) of estimated new cancer cases in 1992. The estimated mortality rate is even higher (32%), which is reflected in a 5-year survival rate of only 7% and 12% for esophageal and lung cancer, respectively. Tobacco use appears to remain the major cause of aerodigestive cancers despite efforts at primary prevention--cessation of exposure. Another strategy to decrease this public health problem is secondary prevention or chemoprevention. Cancer chemoprevention is defined as intervention with chemical agents before invasion to halt or slow the carcinogenic process; potential agents may include minor dietary constituents and pharmaceuticals. The main objective of the Division of Cancer Prevention and Control (DCPC), National Cancer Institute, is to develop promising chemopreventive drugs for use in humans. The testing of cancer chemopreventives for efficacy in the clinic differs from that of cancer treatment drugs. Chemopreventive drug trials involve healthy target populations, and the endpoints are reduced cancer incidence or mortality, or increased latency, with no to minimal toxicity. The lung and upper aerodigestive tract represent a unique opportunity for intervention in this setting. Even with cessation of tobacco exposure, the risk of cancer in the entire epithelium remains high for years due to the "field cancerization" effect. Some of the first chemopreventive trials made use of this system due to the availability of a study population with a tissue at demonstrably high risk for malignant progression. Much of the evidence for chemopreventive efficacy is in the oral cavity because of the well-defined epithelial neoplastic progression, the existence of well-established preclinical models, and relative ease of tissue monitoring and sampling. In one of the first randomized trials, Hong and co-workers demonstrated that 13-cis-retinoic acid prevents the appearance of second primary tumors in patients previously treated for squamous cell carcinomas of the oral cavity and upper respiratory tract. Even using a high risk population, chemoprevention trials involve large sample sizes, lengthy duration and follow-up, and high cost. To circumvent these problems, the use of intermediate biomarkers as surrogate endpoints is being explored. Intermediate biomarkers are defined as biological alterations in tissue (histological, genetic, biochemical, proliferative, differentiation-related) occurring prior to cancer development. In the oral cavity, studies using modulation of a histological intermediate biomarker, dysplastic leukoplakia, as the endpoint have demonstrated response to a retinoid.(ABSTRACT TRUNCATED AT 400 WORDS)

Squamous cell metaplasia in the human lung: molecular characteristics of epithelial stratification

Squamous cell metaplasia (SCM) is a frequent epithelial alteration of the human tracheobronchial mucosa. This review pays particular attention to the fact that SCM can mimic esophageal, and in some instances even skin-type differentiation, showing striking similarities not only in morphology but also in terms of gene expression. Therefore, characterization of this dynamic process lends insight into the process of stratification, squamous cell formation, and "keratinization" in a pathologically relevant in vivo situation in man. First, the concept of metaplasia is presented with certain historical viewpoints on histogenesis. Then, the morphological characteristics of normal bronchial epithelium are compared with the altered phenotype of cells in SCM. These changes are described as a disturbance of the finely tuned balance of differentiation and proliferation through the action of a variety of extrinsic and intrinsic factors. Molecular aspects of altered cell/cell and cell/extracellular matrix interactions in stratified compared with single-layered epithelia are discussed with reference to SCM in the lung. Intracellular organizational and compositional changes are then summarized with special emphasis on the differential distribution of the cytokeratin (CK) polypeptides. Finally, the still unresolved problems of the histogenetic relationships between normal bronchial mucosa, SCM, and pulmonary neoplasms are addressed. As these questions remain open, examples for detection of well defined "markers" are provided that may be employed as objective criteria for determining clinically important cellular differentiation features.

Intake of vegetables, fruits, beta-carotene, vitamin C and vitamin supplements and cancer incidence among the elderly: a prospective study

A cohort of 11,580 residents of a retirement community initially free from cancer were followed from 1981 to 1989. A total of 1,335 incident cancer cases were diagnosed during the period. Relative risks of cancer were calculated for baseline consumption of vegetables, fruits, beta-carotene, dietary vitamin C, and vitamin supplements. After adjustment for age and smoking, no evidence of a protective effect was found for any of the dietary variables in men. However, an inverse association was observed between vitamin C supplement use and bladder cancer risk. In women, reduced cancer risks of all sites combined and of the colon were noted for combined intake of all vegetables and fruits, fruit intake alone, and dietary vitamin C. Supplemental use of vitamins A and C showed a protective effect on colon cancer risk in women. There was some suggestion that beta-carotene intake and supplemental use of vitamin A, C, and E were associated with reduced risk of lung cancer in women, but none of these results were statistically significant. These inverse associations observed in women seem to warrant further investigation, although there was inconsistency in results between the sexes.

beta-Carotene-mediated inhibition of a DNA adduct induced by 7,12-dimethylbenz(a)anthracene and 7-hydroxymethyl-12-methylbenz(a)anthracene in mouse mammary gland in vitro

The influence of beta-carotene on the formation of DNA-adducts induced by 7,12-dimethylbenz(a)anthracene (DMBA) and 7-hydroxymethyl-12-methylbenz(a)anthracene (7-OHM-12-MBA) during transformation of mouse mammary cells in organ culture was analysed. Treatment with beta-carotene (10(-8)-10(-5) mol/l) caused inhibition (48.8-94.4%) of an adduct (VI), which was detectable in DNA samples from DMBA-treated mammary glands. Out of six adducts, derived from further analysis of DNA samples from 7-OHM-12-MBA-treated glands, adduct f eluted in the same fraction as adduct (VI), indicating these adducts were analogous. Likewise, adduct f was also inhibited by beta-carotene. Boronate chromatographic analysis revealed this particular adduct was a syn-dihydrodiol epoxide product. Adduct inhibition was detectable both at the start and after DMBA treatment. alpha-Tocopherol and canthaxanthin were ineffective in inhibiting adducts. It is reasonable to conclude that beta-carotene-mediated modification of adducts is associated with the inhibition of a syn-adduct, which is derived from further metabolism of a 7-OHM-12-MBA intermediate.