Nutrition and oral cancer

An Integrated Approach for Preventing Oral Cavity and Oropharyngeal Cancers: Two Etiologies with Distinct and Shared Mechanisms of Carcinogenesis

Head and neck squamous cell carcinoma (HNSCC) was the 7th most common malignancy worldwide in 2018 and despite therapeutic advances, the overall survival rate for oral squamous cell carcinoma (OSCC; ∼50%) has remained unchanged for decades. The most common types are OSCC and oropharyngeal squamous cell carcinoma (OPSCC, survival rate ∼85%). Tobacco smoking is a major risk factor of HNSCC. In the developed world, the incidence of OSCC is declining as a result of tobacco cessation programs. However, OPSCC, which is also linked to human papillomavirus (HPV) infection, is on the rise and now ranks as the most common HPV-related cancer. The current state of knowledge indicates that HPV-associated disease differs substantially from other types of HNSCC and distinct biological differences between HPV-positive and HPV-negative HNSCC have been identified. Although risk factors have been extensively discussed in the literature, there are multiple clinically relevant questions that remain unanswered and even unexplored. Moreover, existing approaches (e.g., tobacco cessation, vaccination, and chemoprevention) to manage and control this disease remain a challenge. Thus, in this review, we discuss potential future basic research that can assist in a better understanding of disease pathogenesis which may lead to novel and more effective preventive strategies for OSCC and OPSCC.

Role of Poor Oral Hygiene in Causation of Oral Cancer-a Review of Literature

Oral squamous cell carcinomas (OSCC) are among the commonest cancers in South East Asia and more so in the Indian subcontinent. The role of tobacco and alcohol in the causation of these cancers is well-documented. Poor oral hygiene (POH) is often seen to co-exist in patients with OSCC. However, the role of poor oral hygiene in the etio-pathogenesis of these cancers is controversial. We decided to evaluate the available literature for evaluating the association of POH with OSCC. A thorough literature search of English-language articles in MEDLINE, PubMed, Cochrane Database of Systematic Reviews, and Web of Science databases was conducted, and 93 relevant articles were short-listed. We found that POH was strongly associated with oral cancers. It aids the carcinogenic potential of other known carcinogens like tobacco and alcohol. Even on adjusting for known confounding factors like tobacco, alcohol use, education, and socio-economic strata, presence of POH exhibits higher odds of developing oral cancer.

Economic burden of cancer in India: Evidence from cross-sectional nationally representative household survey, 2014

With the ongoing demographic and epidemiological transition, cancer is emerging as a major public health concern in India. This paper uses nationally representative household survey to examine the overall prevalence and economic burden of cancer in India. The age-standardized prevalence of cancer is estimated to be 97 per 100,000 persons with greater prevalence in urban areas. The evidence suggests that cancer prevalence is highest among the elderly and also among females in the reproductive age groups. Cancer displays a significant socioeconomic gradient even after adjusting for age-sex specifics and clustering in a multilevel regression framework. We find that out of pocket expenditure on cancer treatment is among the highest for any ailment. The average out of pocket spending on inpatient care in private facilities is about three-times that of public facilities. Furthermore, treatment for about 40 percent of cancer hospitalization cases is financed mainly through borrowings, sale of assets and contributions from friends and relatives. Also, over 60 percent of the households who seek care from the private sector incur out of pocket expenditure in excess of 20 percent of their annual per capita household expenditure. Given the catastrophic implications, this study calls for a disease-based approach towards financing such high-cost ailment. It is suggested that universal cancer care insurance should be envisaged and combined with existing accident and life insurance policies for the poorer sections in India. In concluding, we call for policies to improve cancer survivorship through effective prevention and early detection. In particular, greater public health investments in infrastructure, human resources and quality of care deserve priority attention.

Lugol Chromoscopy in the Follow-up of Head and Neck Carcinoma

Introduction:

Lugol is helpful in identifying early second primary tumors (SPTs) during oroscopy and pharyngoscopy, but this technique has not been assessed during follow-up visits with these patients.

Aim:

The aim of this study is to describe the use of Lugol (a low-cost method) to diagnose SPTs in the oral cavity and oropharynx.

Methods:

Patients treated for squamous cell carcinoma of the head and neck were randomly assigned to two groups. Group A was examined with routine oroscopy and pharyngoscopy without Lugol, and Group B was examined with routine oroscopy and pharyngoscopy without stain and with Lugol. A total of 211 patients were included during 4 years.

Results:

Six oral and oropharynx carcinomas were detected in Group A. Eighteen oral and oropharynx carcinomas were detected in Group B, twelve of which were not seen without chromoscopy but were detected with Lugol.

Conclusion:

Lugol increases the detection of malignant lesions compared to routine examination alone.

Association Studies of HFE C282Y and H63D Variants with Oral Cancer Risk and Iron Homeostasis Among Whites and Blacks

Background: Polymorphisms in the hemochromatosis (HFE) gene are associated with excessive iron absorption from the diet, and pro-oxidant effects of iron accumulation are thought to be a risk factor for several types of cancer. Methods: The C282Y (rs1800562) and H63D (rs1799945) polymorphisms were genotyped in 301 oral cancer cases and 437 controls and analyzed in relation to oral cancer risk, and serum iron biomarker levels from a subset of 130 subjects. Results: Individuals with the C282Y allele had lower total iron binding capacity (TIBC) (321.2 ± 37.2 µg/dL vs. 397.7 ± 89.0 µg/dL, p = 0.007) and higher percent transferrin saturation (22.0 ± 8.7 vs. 35.6 ± 22.9, p = 0.023) than wild type individuals. Iron and ferritin levels approached significantly higher levels for the C282Y allele (p = 0.0632 and p = 0.0588, respectively). Conclusions: Iron biomarker levels were elevated by the C282Y allele, but neither (rs1800562) nor (rs1799945) was associated with oral cancer risk in blacks and whites.

Clinico-epidemiological profile of oral potentially malignant and malignant conditions among areca nut, tobacco and alcohol users in Eastern India: A hospital based study

Context:

With an increase in the abuse of various oral habitual products in India over the past few decades; the incidence of oral potentially malignant conditions as leukoplakia, oral submucous fibrosis and squamous cell carcinoma (SCC) rates have also increased. No recent study has been conducted reporting the scenario of oral cancer and potentially malignant conditions in Eastern India (specifically Kolkata).

Aims:

The present study was conducted at Dr. R. Ahmed Dental College, Kolkata during 2010-2011 to find a possible correlation between the effects of the different oral habits, age, sex and the different types of oral mucosal lesions among patients reported to the hospital. This study also enabled us to see the predilection of the various histopathological stages of the lesions for different sites of the oral cavity.

Subjects and Methods:

The study group consisted of 698 patients having either oral potentially malignant or malignant lesion. The control group consisted of 948 patients who had reported to the hospital for different oral/dental problems and had the habit of tobacco, areca nut and/or alcohol usage for at least 1 year.

Statistical Analysis:

The unadjusted odds ratio, the 95% confidence interval, and the P value were calculated to correlate patients with/without different kinds of habit and having/not having various kinds of oral lesions.

Results:

Our study shows that for males having the habit of taking smokeless tobacco or mixed habit poses the highest risk for developing SCC. For females, significant risk of developing SCC was found in patients habituated to processed areca nut chewing.

Conclusion:

This study presents probably for the first time in recent years the occurrence of oral potentially malignant and malignant conditions amongst patients having deleterious habits in a hospital based population of Kolkata.

Oral cancer prevention and early detection: knowledge and practice among Saudi Arabian healthcare practitioners

PURPOSE

Despite the crucial role that healthcare practitioners (HCPs) have in preventing and detecting oral cancer (OC), studies suggest that dentists and physicians do not adequately detect early stage OC which is attributed to their attitude and knowledge. This Saudi Arabian study aims to assess HCP's knowledge and practice vis-à-vis OC's risk factors and patient evaluation.

DESIGN/METHODOLOGY/APPROACH

A questionnaire was distributed to HCPs in six different Saudi Arabian settings. A total of 16 items representing a mixture of OC's risk and non-risk factors were measured.

FINDINGS

The study found that only 20.9 percent of HCPs could distinguish 11 items or more correctly. Additionally, when HCPs obtained the patient's medical history, no more than 32.3 percent routinely assessed ten important OC issues. Almost 36 percent of HCPs thought that attending to too many patients prevented them from taking proper medical histories, and 37.6 percent admitted that more training in preventing and detecting OC is needed.

RESEARCH LIMITATIONS/IMPLICATIONS

Since there is no effective automated system to reach Saudi Arabian practitioners, the number of practitioners involved in this study is limited.

PRACTICAL IMPLICATIONS

The knowledge and practice of HCPs with relation to OC do not appear to be sufficient and HCPs should have better and more training in OC prevention and early detection.

ORIGINALITY/VALUE

It appears that Saudi Arabian HCPs do not adequately participate in OC's prevention and early detection. It is suggested that continuous education strategies in Saudi Arabia should be reassessed and emphasis given to OC diagnosis.

American Cancer Society Guidelines on nutrition and physical activity for cancer prevention: reducing the risk of cancer with healthy food choices and physical activity

The American Cancer Society (ACS) publishes Nutrition and Physical Activity Guidelines to serve as a foundation for its communication, policy, and community strategies and, ultimately, to affect dietary and physical activity patterns among Americans. These Guidelines, published approximately every 5 years, are developed by a national panel of experts in cancer research, prevention, epidemiology, public health, and policy, and they reflect the most current scientific evidence related to dietary and activity patterns and cancer risk. The ACS Guidelines focus on recommendations for individual choices regarding diet and physical activity patterns, but those choices occur within a community context that either facilitates or creates barriers to healthy behaviors. Therefore, this committee presents recommendations for community action to accompany the 4 recommendations for individual choices to reduce cancer risk. These recommendations for community action recognize that a supportive social and physical environment is indispensable if individuals at all levels of society are to have genuine opportunities to choose healthy behaviors. The ACS Guidelines are consistent with guidelines from the American Heart Association and the American Diabetes Association for the prevention of coronary heart disease and diabetes, as well as for general health promotion, as defined by the 2010 Dietary Guidelines for Americans and the 2008 Physical Activity Guidelines for Americans.

Trends in oral, pharyngeal and oesophageal cancer mortality in Australia: the comparative importance of tobacco, alcohol and other risk factors

OBJECTIVE

The relationship of long-term population-level trends in oral, pharyngeal and oesophageal cancer mortality with major risk factors such as tobacco consumption have not been statistically analysed in Australia. We have demonstrated the long-term implications using historical data.

METHODS

Estimated age and sex-specific tobacco consumption back-extrapolated to 1887 were used together with alcohol and fruit and vegetable consumption data to examine their association with trends in oral, pharyngeal and oesophageal cancer mortality. Log-linear Poisson regression models were applied to specify the relationship with oesophageal and pharyngeal mortality data.

RESULTS

Oral cancer mortality for males decreased sharply in the first half of the 20th Century in contrast to steadily rising tobacco consumption. Female oral and pharyngeal cancer remained steady at low levels. Post-World War II male and female oesophageal and male pharyngeal cancer mortality rose, then either fell or stabilised, without a clear relationship with risk factors.

CONCLUSIONS

Tobacco and alcohol consumption have influenced post-World War II trends in oral, pharyngeal and oesophageal cancer mortality. However, the challenges in using historical population level data prevent precise interpretation of findings.

IMPLICATIONS

There is increased exposure to risk factors for these cancers in many low- and middle-income countries. In particular, smoking cessation programs are needed to prevent increases in mortality from these cancers in such countries.

Lycopene: features and potential significance in the oral cancer and precancerous lesions

Data from epidemiological studies have indicated that diets rich in fruits and vegetables are likely to benefit many aspects of the prevention of oral malignancy. Lycopene is a red-coloured carotenoid predominantly accumulated in tomatoes as well as other fruits and vegetables. It has been claimed to alleviate chronic diseases such as cancers and cardiovascular disease. Hence, the aim of this review is to summarize the features and its potential significance of lycopene in the development, prevention and treatment of oral premalignant lesions and oral cancer. Studies showed that lycopene might have beneficial effects in the management of some premalignant lesions in the oral cavity including oral submucous fibrosis and oral leukoplakia and may be an adjunct in the prevention and therapy of oral cancer. However, more mechanistic studies and randomized controlled trials of large sample size are necessary to further confirm these effects and to eventually make lycopene to be used in the community prevention and clinically routine management of these diseases.

Blood iron, glutathione, and micronutrient levels and the risk of oral cancer

The risk of oral cavity cancer was determined in relation to serological levels of iron; vitamins A, B2, C, E; zinc; thiamin; and glutathione (GSH). The study included 65 hospitalized patients with oral cancer and 85 matched controls. In comparing the highest to the lowest tertiles, the risk was odds ratio (OR) = 0.3 [95% confidence interval (CI) = 0.1-0.6] for iron; 3.2 (95% CI = 1.3-8.1) for total iron binding capacity (TIBC), which measures the concentration of the iron delivery protein transferrin; and 0.4 (95% CI = 0.2-0.9) for transferrin saturation (iron/TIBC x 100). These associations were stronger in never smokers than in ever smokers. The risk associated with the iron storage protein ferritin was significantly elevated, but this association could reflect disease-related inflammation or comorbidity. The OR for GSH was 0.4 (95% CI = 0.1-0.9), and the OR for GSH reductase activity coefficient (indicative of riboflavin deficiency) was 1.6 (95% CI = 1.3-3.7). These findings suggest that mild iron deficiency and low GSH levels, which are associated with increased oxidative stress, increase the risk of oral cavity cancer.

Current topics in the epidemiology of oral cavity and oropharyngeal cancers

Oral cancer incidence rates rose dramatically during the twentieth century in the United States and Europe, especially among individuals under the age of 60 years. Although influenced by age, sex, and country of origin, incidence trends were most strongly affected by elevated risk among individuals born after approximately 1915. This cohort effect was indicative of strong behavioral influences on oral cancer risk. In this article, associations between oral cancer risk and established behavioral risk factors including alcohol and tobacco use are reviewed. Additionally, possible associations between oral cancer risk and oral hygiene, diet, nutritional status, and sexual behavior as well as the influence of genetic factors on oral cancer risk are considered. Special emphasis is placed on evaluating possible risk differences in individuals above and below the age of 45 and in users and nonusers of alcohol and tobacco.

Prospective study of vitamins C, E, and A and carotenoids and risk of oral premalignant lesions in men

Case-control studies indicate that vitamins C, E, A and carotenoids decrease risk of oral premalignant lesions (OPLs) and oral cancer, but clinical trials have failed to find protective effects of beta-carotene and suggest that vitamin E may increase risk. The authors prospectively evaluated the association between intake of vitamins C, E, A and carotenoids and incidence of OPL. Participants were 42,340 men in the Health Professionals Follow-up Study who provided information on supplement use and diet every 2-4 years by food frequency questionnaire. The authors confirmed 207 clinically or histopathologically diagnosed OPL events occurring between 1986 and 2002 by medical record review. Multivariate-adjusted relative risks (RR) of OPL were calculated with proportional hazards models. Total intake of vitamin C, vitamin A or carotenoids was not significantly associated with OPL risk. Dietary vitamin C was significantly associated with reduced risk (quintile 5 vs. 1, RR = 0.52, 95% CI 0.31-0.85, p(trend) = 0.04), but no association with supplemental vitamin C was observed. Inverse associations were apparent for beta-cryptoxanthin and alpha-carotene intake. No clear relationship emerged with beta-carotene, lycopene or lutein/zeaxanthin. Vitamin E was associated with increased risk (quintile 5 vs. 1, RR = 1.86, 95% CI 1.06-3.19), particularly among current smokers and with supplemental intake (current-smokers, supplement dose tertile 3 vs. 1, RR = 3.07, 95% CI 1.28-7.34, p(trend) = 0.01). For current smokers, beta-carotene also increased risk. Vitamin C from dietary sources, but not supplements, was associated with a reduced risk of OPL. The observed increased risk for current smokers with high vitamin E or beta-carotene intake should be explored further.

The role of nutrition in oncology: a need for a change of attitude and curriculum

BACKGROUND

The role of nutrition in cancer is poorly understood by Indian oncologists, who are exposed to minimal education on nutrition in their undergraduate and postgraduate careers.

METHODS

A postal questionnaire survey, without reminder, assessed the knowledge and beliefs about nutrition of 120 oncologists in India (response rate = 58%).

RESULTS

There was a lack of teaching and understanding by surgeons and radiation and medical oncologists about the role of nutrition in prevention, carcinogenesis, treatment, and outcome.

CONCLUSIONS

There needs to be much more emphasis in undergraduate and postgraduate education about the supportive role of nutrition in cancer.

Primary oral cancer in a Turkish population sample: association with sociodemographic features, smoking, alcohol, diet and dentition

The aim of this multicentre case-control study was to investigate the association of a variety of factors with oral cancer in a group of Turkish patients. Questionnaires were used to investigate the sociodemographic features, smoking and alcohol consumptions, dietary habits and dental status of 79 primary oral cancer patients and 61 controls. Data were statistically analysed with Mann-Whitney U-test, Pearson Chi-square and binary logistic regression analyses to determine the odds ratios. Low level of education, gender, dietary habits, having poor oral hygiene and denture sores were associated with primary oral cancer in this patient sample; but eating salads and raw vegetables, fish, and drinking red wine were related with healthy status. Determination of the factors associated with oral cancer and of the high-risk groups would be beneficial to provide efficient screening protocols and prevention programmes for oral cavity cancers.

A-Raf and Raf-1 work together to influence transient ERK phosphorylation and Gl/S cell cycle progression

The Raf/MEK/ERK (extracellular regulated kinase) signal transduction pathway controls the ability of cells to respond to proliferative, apoptotic, migratory and differentiation signals. We have investigated the combined contribution of A-Raf and Raf-1 isotypes to signalling through this pathway by generating mice with knockout mutations of both A-raf and raf-1 genes. Double knockout (DKO) mice have a more severe phenotype than single null mutations of either gene, dying in embryogenesis at E10.5. The DKO embryos show no changes in apoptosis, but staining for Ki67 indicates a generalized reduction in proliferation. DKO mouse embryonic fibroblasts (MEFs) exhibit a delayed ability to enter S phase of the cell cycle. This is associated with a reduction in levels of transiently induced MEK and ERK phosphorylation and reduced expression of c-Fos and cyclin Dl. Levels of sustained ERK phosphorylation are not significantly altered. Thus, Raf-1 and A-Raf have a combined role in controlling physiological transient ERK activation and in maintenance of cell cycle progression at its usual rate.

Dietary Patterns and Risk of Cancer of the Oral Cavity and Pharynx in Uruguay

From 1995 to 2002, a case-control study on food groups and risk of cancer of the oral cavity and pharynx was conducted in Montevideo, Uruguay. Two hundred thirty cases were frequency-matched to 460 controls on age, residence, and urban/rural status. The study was restricted to men. The relationship between foods and risk of oral and pharyngeal squamous cell carcinoma was examined through: 1) individual food group analysis, 2) factor analysis, and 3) determination of empirical scores. The results were similar. Factor analysis generated 2 patterns, which were labeled as "stew" and "vegetables and fruits." The stew pattern loaded positively on boiled meat, cooked vegetables, potato, and sweet potato. This pattern was directly associated with risk of oral and pharyngeal cancer [odds ratio (OR), 3.75; 95% confidence interval (CI), 1.99-7.06; P value for trend=0.0002]. The vegetables and fruits factor loaded positively on raw vegetables, citrus fruits, other fruits, liver, fish, and desserts. This pattern was inversely associated with risk of oropharyngeal carcinoma (OR, 0.34; 95% CI, 0.18-0.64; P value for trend=0.0008). Joint effects of high intake of risk foods and low intake of protective foods were associated with a risk of 12.0 (95% CI, 4.1-34.6). Our study confirms the important role of dietary factors in oral and pharyngeal cancer risk and suggests that the analysis of dietary patterns is a powerful tool to investigate the links between nutrition and cancer.

Patients with oropharyngeal cancer: A comparison of adults living independently and patients living in long-term care facilities

The low survival rate of persons with oropharyngeal cancer (OPC) is directly related to the size of the primary tumor, lymph node involvement and to the smoking history. The association between medical independence and the survival rate of oral cancer is unclear. The purpose of this study was to assess the survival rate of institutionalized patients with oral cancer compared to those living independently. Information regarding gender, age, tobacco habits, disease characteristics, and survival status were recorded and statistically analyzed from 30 patients with oral cancer who were institutionalized compared to 543 patients with oral cancer who were non-institutionalized. Patients living in long-term care facilities (LTC) were significantly older than the independent patients (67% were 70 years or older versus 28% of independent patients) (p = 0.0001). No differences in smoking habits were noted between the two groups but more patients who were institutionalized stopped smoking at the time of diagnosis (p = 0.47). More patients who were institutionalized were diagnosed with positive lymph node involvement (p = 0.09). Significantly higher all-cause and disease-free 5-year survival rates were noted in the patients living independently, compared to the adults who were institutionalized (32% and 60% compared to 7% and 26% respectively; p < 0.05). The disease-specific 5-year survival was directly related to age (p = 0.001), size of the tumor (p = 0.001), and lymph node involvement (p < 0.001). Significant longer survival rates were observed for patients living independently. The more advanced disease seen in the patients who were institutionalized may be due to a delay in diagnosis, which may be associated with fewer symptoms, limited report of symptoms, a lack of attention or a misdiagnosis of the oral lesion.

Methylenetetrahydrofolate reductase polymorphisms and risk of squamous cell carcinoma of the head and neck: A case-control analysis

Folate deficiency is implicated in cancer risk that may be modulated by a genetic variation in the methylenetetrahydrofolate reductase (MTHFR) gene in folate metabolism. We hypothesized that genetic variants in MTHFR are associated with risk of squamous cell carcinoma of the head and neck (SCCHN). We genotyped 3 MTHFR polymorphisms (C677T, A1298C and G1793A) and estimated their haplotypes in a hospital-based case-control study of 537 SCCHN cases and 545 cancer-free controls. The controls were frequency-matched to the cases by age (+/- 5 years), sex, ethnicity and smoking status. We found that the MTHFR 1298AC/CC genotypes were associated with an approximately 35% reduction in risk of SCCHN (adjusted odds ratio = 0.65; 95% CI = 0.51-0.82) compared to the AA genotype. The MTHFR 677CT and 1793GA/AA genotypes were associated with nonsignificant increased risk of SCCHN compared to the 677CC and 1793GG genotypes, respectively. We estimated that there were 8 haplotypes and 16 haplotype genotypes based on these 3 variants. When we used the haplotypes and assumed that the 677T, 1298A and 1793A alleles were risk alleles, the adjusted odds ratios increased as the number of risk alleles increased: 1.00 for 0-1 variant, 1.85 (1.3-2.5) for any 2 risk alleles and 1.93 (1.4-2.7) for any 3 risk alleles. These results suggest that all 3 MTHFR polymorphisms may play a role in the susceptibility to SCCHN among non-Hispanic whites. Future studies should incorporate detailed data on alcohol consumption, dietary folate intake and related serologic measurements.

New revival of an old biomarker: characterisation of buccal cells and determination of genetic damage in the isolated fraction of viable leucocytes

Buccal cells serve as targets to assess oral exposures. We have refined isolation methods to characterise yield, viabilities, types of cells and baseline levels of genetic damage. Buccal cells were isolated from mouthwashes of 27 volunteers. They were characterised microscopically and different methods (using antibody-labelled magnetic beads, filtration and gradient centrifugation) were compared to separate epithelial cells from leucocytes. Viability of cells, DNA damage, and activity of glutathione S-transferase (GST) were measured with dye exclusion, microgelelectrophoresis, and biochemically. Mouthwashes contained approximately equal amounts of epithelial cells and leucocytes with detectable GST-activities. Repetitive determinations with mouthwashes from four individuals yielded per sample (3.5+/-1.4)x10(6) epithelial cells and (4.7+/-3.9)x10(6) leucocytes with viabilities of 8 and 94%, respectively. Epithelial cells could not be isolated using antibody-labelled beads, but cell separation with the leukocyte-specific antibody CD45 succeeded, yielding 37% leucocytes with a purity of 95% and viability of 65%. Filtering the mouthwash through a 10 microm filter yielded 57% leucocytes, with 86% purity and 94% viability. When using density gradient centrifugation as the separation method, the recovery of leucocytes was low (22%), but good results were scored for purity (95%) and cell viability (88%). This method was used to isolate leucocytes, which were then subjected to a micro-scale comet assay-modification. It was found that buccal leucocytes obtained from smokers had more DNA damage than cells from non-smokers. In conclusion, suspensions of buccal cells consist in approximately equal parts of epithelial cells and leucocytes. Only leucocytes are sufficiently viable for measuring parameters of cytotoxicity and genotoxicity or for studying modulation of gene expression. The cells are useful targets of non-invasive biomarkers, which could be incorporated as tools in many types of intervention studies.

Oral and oropharyngeal cancer in Spain: influence of dietary patterns

Cancer of the oral cavity and oropharynx is a major public health problem in Spain. Tobacco and alcohol have been identified as the two major risk factors for oral cancer in most western populations. Other risk factors include diets low in fruits and vegetables, but the impact of dietary habits on the risk of these cancers has never been assessed in Spain. The objective of this study was to elucidate the role of dietary habits in oral and oropharyngeal cancer, a multicentric case-control study was conducted in three areas of Spain (Barcelona, Granada and Sevilla) between 1996 and 1999. Cases were 375 patients (71 women), with incident, histologically confirmed cancer of the oral cavity or oropharynx, and controls were 375 subjects (71 women) admitted to hospitals for conditions unrelated to smoking or alcohol drinking. Data were analysed using multivariate logistic regression procedures. After allowance for education, tobacco and alcohol use, a significant inverse association with the risk of oral and oropharyngeal cancer was found for total consumption of total green vegetables (OR 0.54, 95% CI = 0.34-0.87) and total fruit (OR 0.52, 95% CI = 0.34-0.79) with significant trends in risk. We found that the protective effect of each of these food items was consistently larger among current smokers and among heavy alcohol drinkers, following a multiplicative effect model. In conclusion, this study provides further support to the beneficial effect of high intake of vegetables and fruits on the risk of developing cancers of the oral cavity and oropharynx in Spain, particularly among current smokers and heavy alcohol drinkers.

Dietary exposures and oral precancerous lesions in Srikakulam District, Andhra Pradesh, India

OBJECTIVE

To test the effect of dietary nutrients on oral precancerous lesions in a reverse-smoking (i.e. smoking with the glowing end inside the mouth) population in South India.

DESIGN

Case-control. Cases with precancerous lesions were matched to an equal number of lesion-free controls matched on age (+/- 5 years), sex and village. All subjects used tobacco in some form. Dietary data were obtained using an interviewer-administered food-frequency questionnaire, designed for use in this population. All interviews were conducted blinded to the disease status of the subject. Data were analysed using logistic regression.

SETTING

Nineteen rural villages in Srikakulam District, Andhra Pradesh.

SUBJECTS

From a survey of 6007 tobacco users, 485 (79% women) were found to have precancerous, mostly palatal, lesions (cases), and 487 lesion-free subjects were selected as controls.

RESULTS

All eligible subjects consented to participate and nearly all (> 99%) had complete data for analyses. Reverse smoking was the most common form of tobacco use among cases (81.9%) and controls (73.5%), and reverse smokers were 5.19 times more likely than chewers to have these lesions (95% confidence interval = 1.35, 19.9). After controlling for relevant covariates, including the type of tobacco use, protective linear effects were observed for zinc (70% reduction across the interquartile range, P < 0.002), calcium (34% reduction, P < 0.002), fibre (30% reduction, P < 0.009), riboflavin (22% reduction, P < 0.03) and iron (17% reduction, P < 0.05).

CONCLUSIONS

Several dietary nutrients appear to protect against oral precancerous lesions that are strongly associated with reverse smoking. The results of this study indicate scope for targeting dietary factors in preventing oral cancer, which should be coupled with aggressive anti-tobacco use efforts.

Fruit and vegetable consumption in the prevention of cancer: an update

Fruit and vegetables are considered to be important means of preventing cancer through diet. However, several recent large prospective cohort studies and clinical trials have found no associations regarding several major cancers, including cancers of the colon, breast and stomach. Although these results are disconcerting, especially for health-conscious individuals, there is also mounting evidence that people who avoid fruit and vegetables completely, or consume very little, are indeed at increased risk of these cancers. These individuals in particular should be identified, with the goal of helping them find ways to include more fruit and vegetables in their diets.

Protein phosphatases 1 and 2A promote Raf-1 activation by regulating 14-3-3 interactions

Raf-1 activation is a complex process which involves plasma membrane recruitment, phosphorylation, protein-protein and lipid-protein interactions. We now show that PP1 and PP2A serine-threonine phosphatases also have a positive role in Ras dependent Raf-1 activation. General serine-threonine phosphatase inhibitors such sodium fluoride, or ss-glycerophosphate and sodium pyrophosphate, or specific PP1 and PP2A inhibitors including microcystin-LR, protein phosphatase 2A inhibitor I(1) or protein phosphatase inhibitor 2 all abrogate H-Ras and K-Ras dependent Raf-1 activation in vitro. A critical Raf-1 target residue for PP1 and PP2A is S259. Serine phosphatase inhibitors block the dephosphorylation of S259, which accompanies Raf-1 activation, and Ras dependent activation of mutant Raf259A is relatively resistant to serine phosphatase inhibitors. Sucrose gradient analysis demonstrates that serine phosphatase inhibition increases the total amount of 14-3-3 and Raf-1 associated with the plasma membrane and significantly alters the distribution of 14-3-3 and Raf-1 across different plasma membrane microdomains. These observations suggest that dephosphorylation of S259 is a critical early step in Ras dependent Raf-1 activation which facilitates 14-3-3 displacement. Inhibition of PP1 and PP2A therefore causes plasma membrane accumulation of Raf-1/14-3-3 complexes which cannot be activated.

Diet and risk of oral and pharyngeal cancer. An Italian case-control study

The relation between diet and risk of oral and pharyngeal cancer was analysed in a case-control study conducted in North-East Italy between 1996 and 1999. Cases were 132 patients (including 33 women), with incident, histologically confirmed cancer of the oral cavity or pharynx, and controls were 148 subjects (including 45 women) admitted to hospitals for acute conditions unrelated to smoking or alcohol drinking. After allowance for tobacco, alcohol and several other potential confounding factors, significant inverse association with the risk of oral and pharyngeal cancer was found for consumption of total green vegetables (OR 0.37) and total fruit (OR 0.34) with significant trends in risk Compared with alcohol drinkers of < 20 drinks/week and eating > 13 portions/week of total green vegetables, the OR for drinkers of > or = 20 drinks/week and eating < 7 portions/week of green vegetables was 15.44. Our study provides further support to the beneficial effect of high intake of vegetables and fruit, particularly in heavy smokers and alcohol drinkers.

Serum antioxidant micronutrients and the risk of oral leukoplakia among Japanese

A population-based case-control study was designed for the investigation of any association between serum micronutrient levels and oral leukoplakia. Out of a total of 9536 subjects over the age of 40 years who participated in the oral mucosal screening programme in Tokoname city, 48 cases detected with oral leukoplakia (38 male:10 female) were recruited. For each case, four controls matched by age and sex were selected from the same cohort. We examined the fasting serum levels of retinol, alpha-tocopherol, zeaxanthin and lutein, cryptoxanthin, lycopene and carotenoids (alpha-carotene and beta-carotene) by high-performance liquid chromatography. Among males with leukoplakia mean serum lycopene and beta-carotene levels (0.175+/-0.202, 0.357+/-0.295 micromol/l) were significantly lower than those of controls (0.257+/-0.252, 0.555+/-0.408 micromol/l) (P<0.05, P<0.005). Logistic regression analysis with leukoplakia as the dependent variable showed that high serum levels of beta-carotene were related to low risk of oral leukoplakia (odds ratio 0.160, 95% C.I.: 0.029-0.866, P<0.05). There were no significant differences in any of the serum nutrients estimated in female subjects. Our results suggest for the first time that high serum levels of beta-carotene may provide protection against oral precancer for the Japanese male.

Dietary factors and cancer risk

OBJECTIVES

To discuss the relationship between dietary factors and cancer risk reduction, the status of prevention trials in progress, and current dietary recommendations.

DATA SOURCES

Published research and review articles, medical books, and web sites.

CONCLUSIONS

Evidence indicates that dietary factors can reduce the risk of developing cancer. The dietary recommendations for cancer risk reduction are consistent with those for prevention of other chronic diseases and are thus useful for the majority of the population.

IMPLICATIONS FOR NURSING PRACTICE

In their role as educators, it is essential for nurses to provide accurate and timely information on diet and cancer risk reduction to their patients and the public and to encourage compliance with dietary recommendations.

Survey of U.S. dentists' knowledge and opinions about oral pharyngeal cancer

BACKGROUND

Oral pharyngeal cancer constitutes the most life-threatening of all dental and craniofacial conditions. The U.S. five-year survival rate of 52 percent for these cancers is one of the lowest and has not changed in decades.

METHODS

The authors mailed a pretested survey to 7,000 randomly selected general dentists. They obtained information on 3,200 dentists' levels of knowledge about oral pharyngeal cancer risks and diagnostic procedures for providing an oral cancer examination, as well as about related opinions and interest in continuing education, or CE, courses on the topic. The authors carried out analyses using unweighted data; they used both bivariate and logistic analytical techniques and evaluated at a significance level of P < or = .01.

RESULTS

Based on responses to 14 questions, the average knowledge of oral cancer risks score was 8.4. About one-half of dentists surveyed knew the two most common sites of intraoral cancer and that most oral cancers are diagnosed at a late stage.

CONCLUSIONS

The reported knowledge of these dentists regarding oral cancer suggests that they are not as knowledgeable as they could be about cancer prevention and early detection and that they recognize these deficiencies. Most of the dentists were interested in oral cancer CE.

CLINICAL IMPLICATIONS

Dentists need to know where in the mouth to look and what types of lesions to look for to provide a comprehensive oral cancer examination.

Activation of Stat3 preassembled with platelet-derived growth factor beta receptors requires Src kinase activity

Members of the STAT family of transcriptional regulators modulate the expression of a variety of gene products that promote cell proliferation, survival and transformation. Although initially identified as mediators of cytokine signaling, the STAT proteins are also activated by, and thus may contribute to the actions of, polypeptide growth factors. To define the mechanism by which these factors activate STATs, we examined the process of Stat3 activation in Balb/c-3T3 fibroblasts treated with platelet-derived growth factor (PDGF). As STATs are activated by tyrosine phosphorylation, and as PDGF receptors are ligand-activated tyrosine kinases, we considered the possibility that Stat3 interacts with and is phosphorylated by PDGF receptors. We find that Stat3 associates with PDGF beta receptors in both the presence and, surprisingly, the absence of PDGF. Moreover, Stat3 was phosphorylated on tyrosine in PDGF beta receptor immunoprecipitates of PDGF-treated but not untreated cells. Although required, receptor activation was insufficient for Stat3 activation. When added to cells in combination with a pharmacologic agent (PD180970) that specifically inhibits the activity of Src family tyrosine kinases, PDGF did not activate Stat3 as monitored by electrophoretic mobility shift assay. PD180970 did not affect MAPK activation by PDGF or the JAK-dependent activation of Stat3 by interleukin-6. The necessity of Src activity for Stat3 activation by PDGF was further evidenced by data showing the presence of Src in complexes containing both Stat3 and PDGF beta receptors in PDGF-treated cells. These results suggest a novel mechanism of STAT activation in which inactive Stat3 pre-assembles with inactive PDGF receptors, and in response to ligand binding and in a manner dependent on Src kinase activity, is rapidly phosphorylated and activated. Additional data demonstrate that Src kinase activity is also required for PDGF stimulation of DNA synthesis in density-arrested cells.

Oral pharyngeal cancer prevention and early detection. Dentists' opinions and practices

BACKGROUND

The five-year survival rate for patients in the United States diagnosed with oral pharyngeal cancer is 52 percent, which suggests that these cancers are diagnosed at late stages. The authors conducted this study to determine U.S. dentists' opinions and practices regarding oral cancer prevention and early detection.

METHODS

The authors mailed a pretested survey to 7,000 randomly selected general practitioners. A total of 3,200 dentists provided information on how they conduct oral cancer examinations, their use of health history questions to assess patients' oral cancer risks and their oral cancer training and practices. The authors carried out analyses using unweighted data; both bivariate and logistic analytical techniques at a P < or = .01 level of significance were used.

RESULTS

On average, dentists assessed about five of the eight health history items on the survey. Eighty-six percent indicated that they did not conduct oral cancer examinations on edentulous patients 18 years of age or older; 81 percent, however, reported that they conducted oral cancer examinations for 100 percent of their patients 40 years of age or older on their initial appointment.

CONCLUSIONS

The reported practices of these dentists regarding oral cancer, in conjunction with their opinions about key aspects of these practices and their training, point to a need for systematic educational updates in oral cancer prevention and early detection.

CLINICAL IMPLICATIONS

Dentists need to determine their patients' risks for oral cancers and provide routine and comprehensive oral cancer examinations.

Selected micronutrients and oral and pharyngeal cancer

The relation between selected micronutrients and oral and pharyngeal cancer risk was investigated using data from a case-control study conducted between January 1992 and November 1997 in Italy and Switzerland. Cases were 754 incident, histologically confirmed oral cancers (344 of the oral cavity and 410 of the pharynx) admitted to the major teaching and general hospitals in the study areas. Controls were 1,775 subjects with no history of cancer admitted to hospitals in the same catchment areas for acute, non-neoplastic diseases. Dietary habits were investigated using a validated food-frequency questionnaire. Odds ratios (ORs) were computed after allowance for age, sex, center, education, occupation, body mass index, smoking and drinking habits and non-alcohol energy intake. Micronutrients were analyzed both as continuous variables and in quintiles. In the former case, the unit was set to 1 SD of the distribution of controls. ORs for the continuous analysis were 0.95 for retinol, 0.61 for carotene, 0.91 for lycopene, 0.83 for vitamin D, 0.74 for vitamin E, 0.63 for vitamin C, 0.82 for thiamine, 0.87 for riboflavin, 0.59 for vitamin B6, 0.61 for folic acid, 0.62 for niacin, 0.91 for calcium, 0.88 for phosphorus, 0.65 for potassium, 0.82 for iron, 0.67 for non-alcohol iron and 0.89 for zinc; the 95% confidence interval excluded one for carotene, vitamin C and E, thiamine, vitamin B6, folic acid, niacin, potassium and iron. ORs were similar for the 2 sexes and in strata of age. When the combined intake of vitamins C and E and carotene was considered, the protective effect of each nutrient was more marked or restricted to subjects with low intake of the other 2. The association with vitamin C and carotene was independent of smoking and drinking habits, while that with vitamin E was less evident in those heavily exposed to alcohol or tobacco. In general, the more a micronutrient was correlated to total vegetable and fruit intake, the stronger was its protective effect against oral cancer.

Increased salivary acetaldehyde levels in heavy drinkers and smokers: a microbiological approach to oral cavity cancer

The pathogenetic mechanisms behind alcohol-associated carcinogenesis in the upper digestive tract remain unclear, as alcohol is not carcinogenic. However, there is increasing evidence that a major part of the tumour-promoting action of alcohol might be mediated via its first, toxic and carcinogenic metabolite acetaldehyde. Acetaldehyde is produced from ethanol in the epithelia by mucosal alcohol dehydrogenases, but much higher levels derive from microbial oxidation of ethanol by the oral microflora. In this study we investigated factors that might alter the composition and quantities of the oral microflora and, consequently, influence microbial acetaldehyde production. Information about dental health, smoking habits, alcohol consumption and other factors was obtained by a questionnaire from 326 volunteers with varying social backgrounds and health status, e.g. oral cavity malignancy. Paraffin-induced saliva was collected and the microbial production of acetaldehyde from ethanol was measured. Smoking and heavy drinking were the strongest factors increasing microbial acetaldehyde production. Whether poor dental status may alter local acetaldehyde production from ethanol remained unanswered. Bacterial analysis revealed that mainly gram-positive aerobic bacteria and yeasts were associated with higher acetaldehyde production. Increased local microbial salivary acetaldehyde production due to ethanol among smokers and heavy drinkers could be a biological explanation for the observed synergistic carcinogenic action of alcohol and smoking on upper gastrointestinal tract cancer. It offers a new microbiological approach to ethanol-associated carcinogenesis at these anatomic sites.

Ras signaling through PI3K confers hormone-independent proliferation that is compatible with differentiation

Hormones are specialized mitogens that stimulate proliferation in their differentiated target cells. Thyrotropin (TSH), the physiologic regulator of thyroid cells, stimulates cAMP-mediated proliferation and thyroid-specific gene expression. The mitogenic effects of TSH require Ras, therefore Ras activation should be compatible with the maintenance of thyroid differentiation. However, expression of activated Ras extinguishes the differentiated phenotype of thyroid cells. One explanation for this apparent paradox is the selective utilization of Ras effector pathways. We tested the hypothesis that Ras signaling through PI3K mediates the mitogenic effects of TSH in cells which retain their differentiated character. Expression of a Ras effector mutant (RasV12S35) that signals preferentially through Raf-1, although sufficient to confer TSH-independent proliferation, abolished hormone-regulated expression of thyroglobulin and the sodium/iodide symporter. In contrast, expression of a Ras mutant (RasV12C40) that binds selectively to PI3K conferred TSH-independent proliferation without marked effects on thyroid-specific gene expression. Unlike the inhibitory effects of TSH on the proliferation of RasV12S35-expressing cells, TSH enhanced RasV12C40-stimulated proliferation by further increasing the activity of p70s6k, an important mediator of the mitogenic effects of TSH and RasV12C40. These results demonstrate that channeling Ras-dependent signals to PI3K confers TSH with the ability to stimulate proliferation in differentiated cells. Oncogene (2000) 19, 924 - 932.

Activation of mitogen-activated protein kinase is necessary but not sufficient for proliferation of human thyroid epithelial cells induced by mutant Ras

Given the high frequency of ras oncogene activation in several common human cancers, its signal pathways are an important target for novel therapy. For practical reasons, however, these have been studied mainly in the context of transformation of established fibroblast cell lines, whereas ras acts at an earlier stage in human tumorigenesis and predominantly on epithelial cells. Here we have developed a more directly relevant model - human primary thyroid epithelial cells - which are a major target of naturally-occurring Ras mutation, and in which expression of mutant Ras in culture induces clonal expansion without morphological transformation, closely reproducing the phenotype of the corresponding tumour in vivo. Transient or stable expression of mutant H-ras (by scrapeloading or retroviral infection) at levels which stimulated proliferation induced sustained activation and translocation of MAP kinase (MAPK) in these cells. Inhibition of the MAPK pathway at the level of MAPKK, by expression of a dominant-negative mutant or by the pharmacological inhibitor PD98059, efficiently blocked the proliferative response. Conversely, selective activation of MAPK by a constitutively-active MAPKK1 mutant failed to mimic the action of Ras and, although this was achievable with activated Raf, micro-injection of anti-ras antibodies showed that this still required endogenous wild-type Ras function. In contrast to recent results obtained with a rodent thyroid cell line (WRT), therefore, activation of the MAPK pathway is necessary, but not sufficient, for the proliferogenic action of mutant Ras on primary human thyroid cells. These data emphasize the unreliability of extrapolation from cell lines and establish the feasibility of using a more representative human epithelial model for Ras signalling studies.

Interactions of c-Raf-1 with phosphatidylserine and 14-3-3

Activation of Raf-1 occurs at the plasma membrane. We recently showed that 14-3-3 must be complexed with Raf-1 for efficient recruitment to the plasma membrane and activation by Ras, but that 14-3-3 is completely displaced from Raf-1 following plasma membrane binding. We show here that the Raf-1 zinc finger is not absolutely required for 14-3-3 binding but is required to stabilize the interaction between Raf-1 and 14-3-3. Incubation of Raf-1 with phosphatidylserine, an inner plasma membrane phospholipid, results in removal of 14-3-3 and an increase in Raf-1 kinase activity, whereas removal of 14-3-3 from Raf-1 using specific phosphopeptides substantially reduces Raf-1 basal kinase activity. Displacement of 14-3-3 from activated Raf-1 by phosphopeptides has no effect on kinase activity if Raf-1 is first removed from solution, but completely eradicates kinase activity of soluble activated Raf-1. These results suggest a mechanism for the removal of 14-3-3 from Raf-1 at the plasma membrane and show that removal of 14-3-3 from Raf-1 has markedly different effects depending on experimental conditions.

Risk factors for oral and pharyngeal cancer in never smokers

Information on the etiology of oral and pharyngeal cancer in never smokers should help us to understand and quantify risk factors for the disease in the absence of the residual confounding and interaction by smoking. Out of a total of 528 cases with histologically confirmed incident cancers of the oral cavity and pharynx, 42 (10 men and 32 women) who described themselves as lifelong non-smokers were considered. Controls were 864 lifelong non-smokers (442 men and 422 women) admitted to hospital for acute, non-neoplastic, non-alcohol-related conditions. The major risk factor for cancer of the oral cavity and pharynx in never smokers was alcohol consumption (mainly wine) with an odds ratio (OR) about three-fold higher in drinkers than non-drinkers. A direct relation was also found for the duration of the habit, with an OR of 3.6 (95% confidence intervals, CI, 1.2-11.2) for drinking for 35 years or longer. Among the few selected indicator foods considered, a direct association was found with butter (OR 2.7, 95% CI 1.4-5.1 for high intake compared to low), and a non-significant inverse association with carrots (OR 0.6, 95% CI 0.3-1.3) and fresh fruit (OR 0.7, 95% CI 0.3-1.6) for the highest tertile of intake compared to the lowest. Thus, even in the absence of smoking, reducing alcohol and saturated fat intake and increasing fruit and carrot consumption may have favorable effects on oral and pharyngeal cancer risk.

Incidence of and survival from upper aerodigestive tract cancers in the U.K.: the influence of deprivation

The aim of the study was to investigate the effect of social deprivation on the incidence of and survival from upper aerodigestive tract (UAT) cancers in the U.K. Incidence was calculated on 25,903 cases of malignant upper aerodigestive tract cancers collected from four cancer registries in the U.K. for the period 1984-1993. A Cox proportional hazard model was used to determine the influence of deprivation, measured in Carstairs quintiles for crude and cause-specific survival on 17,393 of these cases. Patients with UAT cancers who were younger, males or of South Asian origin were more likely to live in a deprived area than in an affluent area. The incidence of UAT cancers in a district was correlated with deprivation score for the district for both men (r = 0.78) and for women (r = 0.60). People who lived in deprived areas had a relative risk of 1.25 (95% confidence interval (CI): 1.15-1.35) of dying from their cancer and of 1.24 (95% CI: 1.13-1.35) of dying from all causes compared with people who lived in affluent areas. People living in deprived areas were more likely to get UAT cancer and were more likely to die from their cancer than people living in affluent areas.

Influence of dietary factors on oral precancerous lesions in a population-based case-control study in Kerala, India

BACKGROUND

Although tobacco is the primary etiologic factor for oral precancerous lesions in India, evidence from other sources indicates that diet may modify risk. This case-control study was designed to minimize a variety of biases in its attempt to investigate the relation between diet and oral precancerous lesions.

METHODS

In a house-to-house survey of 5056 tobacco users in a rural area of Ernakulam district in Kerala, India, 226 individuals (44 females and 182 males) were found to have precancerous lesions (cases), which in 4 cases proved to be cancer. From among the examinees, an equal number of controls who were free of oral mucosal lesions and were matched to the cases regarding age (+/-5 years), gender, ward of residence, and use of tobacco also were enrolled. Dietary data were obtained using a customized interviewer-administered food-frequency questionnaire. All subjects and interviewers were blinded to the disease status of the subject.

RESULTS

After controlling for tobacco use, intake of fruits, vegetables, and beta-carotene evinced inverse trends in risk (P<0.05), with an average reduction of over 10% per quartile of exposure. Associations with certain micronutrients appeared to differ according to gender, with an apparent 20% reduction in risk per mg of zinc consumed per day among men and the suggestion of an increased risk among those women in the lowest quartile of iron intake (an increase of approximately 2.5-fold) and ascorbic acid intake (an increase of approximately 70% increase) compared with other women (P<0.10).

CONCLUSIONS

Consumption of vegetables, fruits, and several micronutrients may inhibit precancerous lesions of the oral cavity.

Diet and risk of cancer of the upper aerodigestive tract--II. Nutrients

In order to examine the risks of cancer of the upper aerodigestive tract (UADC) associated with nutrient intake, a case-control study was conducted in Uruguay in the period of January 1996-December 1997. All patients afflicted with cancer of the oral cavity, pharynx, larynx, and esophagus, were included in the study. Cases were frequency-matched with hospitalized patients on age, sex, residence, and urban/rural status. A strong positive association with protein intake was observed (OR 2.5, 95% CI 1.5-4.4), whereas antioxidants were associated with an inverse association (OR for vitamin C 0.5, 95% CI 0.3-0.8). Non-nutritive substances, like flavonoids displayed a marked reduction in risk of 70%. Possible mechanisms for these findings are discussed.

Diet and risk of cancer of the upper aerodigestive tract--I. Foods

In order to examine the risks of cancer of the upper aerodigestive tract associated with food groups, a case-control study was conducted in Uruguay in the period January 1996-December 1997. All patients afflicted with cancer of the oral cavity, pharynx larynx, and esophagus, were included in the study. Cases were frequency matched with hospitalized patients on age, sex, residence, and urban/rural status. A strong association with red meat intake was observed (OR 2.4, 95% CI 1.2-4.8), whereas vegetables fruits and legumes were associated with an inverse association (OR for fruits 0.3, 95% CI 0.2-0.6). Salted meat, a possible source of nitrosamines, was associated with an increased risk of 60% for esophageal cancer. Possible mechanisms for these findings are discussed.

Dietary factors in oral leukoplakia and submucous fibrosis in a population-based case control study in Gujarat, India

OBJECTIVES

To investigate the relationship of specific nutrients and food items with oral precancerous lesions among tobacco users.

DESIGN

A population-based case-control study.

SETTING

Villages in Palitana taluk of Bhavnagar district, Gujarat, India.

SUBJECTS AND METHODS

An interviewer-administered food frequency questionnaire, developed and validated for this population, was used to estimate nutrient intake in blinded, house-to-house interviews. Among 5018 male tobacco users, 318 were diagnosed as cases. An equal number of controls matched on age (+/- 5 years), sex, village, and use of tobacco were selected.

MAIN OUTCOME MEASURES

Odds ratios (OR) from multiple logistic regression analysis controlling for relevant variables (type of tobacco use and economic status).

RESULTS

A protective effect of fibre was observed for both oral submucous fibrosis (OSF) and leukoplakia, with 10% reduction in risk per g day-1 (P < 0.05). Ascorbic acid appeared to be protective against leukoplakia with the halving of risk in the two highest quartiles of intake (versus the lowest quartile: OR = 0.46 and 0.44, respectively; P < 0.10). A protective effect of tomato consumption was observed in leukoplakia and a suggestion of a protective effect of wheat in OSF.

CONCLUSION

In addition to tobacco use, intake of specific nutrients may have a role in the development of oral precancerous lesions.

Food groups and risk of oral and pharyngeal cancer

The role of specific food groups and diet variety on the risk of oral and pharyngeal cancer has been considered using data from a case-control study conducted between 1992 and 1997 in the Swiss Canton of Vaud. Cases were 156 patients (126 males, 30 females) aged under 75 (median age 56) years with incident, histologically confirmed cancer of the oral cavity and pharynx, and controls were 284 subjects (246 males, 38 females, median age 57 years), admitted to the same university hospital for a wide spectrum of acute, non-neoplastic conditions unrelated to tobacco and alcohol consumption or to long-term modification of diet. After allowance for education, alcohol, tobacco and total energy intake, significant trends of increasing risk with more frequent intake emerged for eggs (OR = 2.3 for the highest tertile), red meat (OR = 2.1) and pork and processed meat (OR = 3.2). Inverse trends in risk were observed for milk (OR = 0.4 for the highest tertile), fish (OR = 0.5), raw vegetables (OR = 0.3), cooked vegetables (OR = 0.1), citrus fruit (OR = 0.4) and other fruits (OR = 0.2). The addition of a serving per day of fruit or vegetables was associated with an about 50% reduction in oral cancer risk. The most favourable diet for oral cancer risk is therefore given by infrequent consumption of red and processed meat and eggs and, most of all, frequent vegetable and fruit intake. Diet diversity was inversely related to oral and pharyngeal cancer: ORs were 0.35 for the highest tertile of total diversity, 0.24 for vegetable and 0.34 for fruit diversity. In terms of attributable risk, high meat intake accounted for 49% of oral and pharyngeal cancers in this population, low vegetable intake for 65% and low fruit intake for 54%.

Whole grain food intake and cancer risk

The relationship between frequency of consumption of whole grain food and risk of selected neoplasms has been analysed using data from an integrated series of case-control studies conducted in northern Italy between 1983 and 1996. The overall dataset included the following incident, histologically confirmed neoplasms: oral cavity and pharynx 181, oesophagus 316, stomach 745, colon 828, rectum 498, liver 428, gallbladder 60, pancreas 362, larynx 242, breast 3,412, endometrium 750, ovary 971, prostate 127, bladder 431, kidney 190, thyroid 208, Hodgkin's disease 80, non-Hodgkin's lymphomas 200, multiple myelomas 120. Controls were 7,990 patients admitted to hospital for acute, non-neoplastic conditions, unrelated to long-term modifications in diet and not likely to have been caused by tobacco or alcohol use. Odds ratios (OR) for subsequent scores (never/occasional/frequent) of whole grain food consumption were derived after allowance for age, sex, education, smoking, alcohol intake and body mass index. High intake of whole grain foods consistently reduced risk of neoplasm at all sites, except thyroid. The ORs for the highest category of consumption were 0.2-0.3 for upper digestive and respiratory tract neoplasms, 0.5 for stomach, colon and gallbladder, 0.7 for rectum, 0.6 for liver, 0.8 for pancreas and prostate, 0.9 for breast and endometrium, 0.6 for ovary, 0.4 for bladder and kidney, 1.3 for thyroid and around 0.5 for lymphomas and myeloma. The tests for trend in risks were significant for all neoplasms, except pancreas, endometrium, Hodgkin's disease and multiple myeloma. No significant heterogeneity was found across strata of age at diagnosis, sex, education, smoking habit, alcohol intake and body mass index. Thus, even in the absence of a univocal and satisfactory biological interpretation, the consistency of the patterns observed indicate that, in this population, higher frequency of whole grain food intake is an indicator of reduced risk of several neoplasms.

Diet, nutrients, and gastrointestinal cancer

Tobacco and alcohol use are strong risk factors for cancer of the upper gastrointestinal tract. Saturated fat and red meat intake also appear to increase the risk of colorectal cancer. The strongest and most consistent dietary protective factors for gastrointestinal cancer are vegetables and fruits. Some micronutrients show beneficial effects, but the degree of protection is less than that observed from whole plant foods. Substantial decreases in the morbidity and mortality from gastrointestinal cancer could occur with more widespread adoption of dietary guidelines designed for cancer prevention.

Epidemiology and prevention of oral cancer

Descriptive epidemiology of oral and pharyngeal cancer over the last four decades is reviewed, with specific focus on Europe. Substantial rises in mortality rates have been observed for younger males, mostly in eastern Europe. The independent role of alcohol and tobacco and their interaction on oral carcinogenesis is discussed, since these factors account for about three quarters of oral cancers in Europe. The influence of dietary factors, and in particular of a diet poor in fresh fruit and vegetables on oral carcinogenesis, is also discussed, since diet may account for 10-15% of oral cancer cases in Europe. Finally, among other carcinogens, the possibility of human papillomavirus involvement in the aetiology of cancer of the oral cavity and pharynx is overviewed. Implications for prevention are discussed.