Diet, living conditions and nasopharyngeal carcinoma in Tunisia--a case-control study

Viral and Clinical Oncology of Head and Neck Cancers

Purpose of Review

This study assesses the current state of knowledge of head and neck squamous cell carcinomas (HNSCC), which are malignancies arising from the orifices and adjacent mucosae of the aerodigestive tracts. These contiguous anatomical areas are unique in that 2 important human oncoviruses, Epstein-Barr virus (EBV) and human papillomavirus (HPV), are causally associated with nasopharyngeal and oropharyngeal cancers, respectively. Mortality rates have remained high over the last 4 decades, and insufficient attention paid to the unique viral and clinical oncology of the different subgroups of HNSCC.

Recent Findings

We have compared and contrasted the 2 double-stranded DNA viruses and the relevant molecular oncogenesis of their respective cancers against other head and neck cancers. Tobacco and alcohol ingestion are also reviewed, as regard the genetic progression/mutation accumulation model of carcinogenesis. The importance of stringent stratification when searching for cancer mutations and biomarkers is discussed. Evidence is presented for a dysplastic/pre-invasive cancerous phase for HPV+ oropharyngeal cancers, and analogous with other HPV+ cancers. This raises the possibility of strategies for cancer screening as early diagnosis will undoubtedly save lives.

Summary

Staging and prognostication have changed to take into account the distinct biological and prognostic pathways for viral+ and viral− cancers. Diagnosis of pre-cancers and early stage cancers will reduce mortality rates. Multi-modal treatment options for HNSCC are reviewed, especially recent developments with immunotherapies and precision medicine strategies. Knowledge integration of the viral and molecular oncogenic pathways with sound planning, hypothesis generation, and clinical trials will continue to provide therapeutic options in the future.

Residence characteristics and risk of nasopharyngeal carcinoma in southern China: A population-based case-control study

OBJECTIVES

Given the role of exposures related to residence in the development of nasopharyngeal carcinoma (NPC) has not been well explored, present study aims to investigate the magnitude and pattern of associations for NPC with lifelong residential exposures.

MATERIALS AND METHODS

We carried out a multi-center, population-based case-control study with 2533 incident NPC cases and 2597 randomly selected population controls in southern China between 2010 and 2014. We performed multivariate logistic regression to estimate odds ratios (ORs) with 95% confidence intervals (CIs) for the risk of NPC associated with residential exposures.

RESULTS

Compared with those living in a building over lifetime, risk of NPC was higher for individuals living in a cottage (OR: 1.56; 95% CI: 1.34-1.81) or in a boat (3.87; 2.07-7.21). NPC risk was also increased in individuals using wood (1.34; 1.03-1.75), coal (1.70; 1.17-2.47), or kerosene (3.58; 1.75-7.36) vs. using gas/electricity as cooking fuel; using well water (1.57; 1.34-1.83), river water (1.80; 1.47-2.21), or spring/pond/stream water (2.03; 1.70-2.41) vs. tap water for source of drinking water; living in houses with smaller-sized vs. larger windows in the bedroom (3.08; 2.46-3.86), hall (1.89; 1.55-2.31) or kitchen (1.67; 1.34-2.08); and increasing exposure to cooking smoke [(1.53; 1.20-1.94) for high exposure)] or burned incense [(1.59; 1.31-1.95) for daily use)]. Weighted Cox regression analysis corroborated these results.

CONCLUSION

Poorer residential conditions and household air pollution are associated with an increased risk of NPC. Large-scale studies in other populations or longitudinal studies are warranted to further corroborate these findings.

The Evolving Epidemiology of Nasopharyngeal Carcinoma

BACKGROUND

The epidemiology of nasopharyngeal carcinoma (NPC) has long been a source of fascination due to the malignancy's striking geographic distribution, the involvement of the oncogenic Epstein-Barr virus (EBV), the unique association with intake of Chinese-style salt-preserved fish, and etiologic heterogeneity by histologic subtype.

METHODS

This review summarizes the current epidemiologic literature on NPC, highlighting recent results from our population-based case-control study in southern China.

RESULTS

Findings from our case-control study provide new insight into the epidemiology of NPC, including a diminished role of Chinese-style salt-preserved fish, a profound impact of EBV genetic sequence variation, modest positive associations with passive smoking and household air pollution, and possible effects of oral health and the oral microbiome. Recent findings from other studies include a protective association with infectious mononucleosis, suggesting a causal role of early EBV infection; familial risk conferred by shared genetic variation in the host antibody-mediated immune response to EBV infection; and an unclear association with occupational exposure to formaldehyde.

CONCLUSIONS

To shed further light on the interplay of environmental, genetic, and viral causes of NPC, large pooled studies must accumulate sufficient cases with detailed exposure data.

IMPACT

New epidemiologic findings have reshaped the causal model for NPC.

Novel Therapies Boosting T Cell Immunity in Epstein Barr Virus-Associated Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma (NPC) is a malignant tumour of the head and neck affecting localised regions of the world, with the highest rates described in Southeast Asia, Northern Africa, and Greenland. Its high morbidity rate is linked to both late-stage diagnosis and unresponsiveness to conventional anti-cancer treatments. Multiple aetiological factors have been described including environmental factors, genetics, and viral factors (Epstein Barr Virus, EBV), making NPC treatment that much more complex. The most common forms of NPCs are those that originate from the epithelial tissue lining the nasopharynx and are often linked to EBV infection. Indeed, they represent 75–95% of NPCs in the low-risk populations and almost 100% of NPCs in high-risk populations. Although conventional surgery has been improved with nasopharyngectomy’s being carried out using more sophisticated surgical equipment for better tumour resection, recent findings in the tumour microenvironment have led to novel treatment options including immunotherapies and photodynamic therapy, able to target the tumour and improve the immune system. This review provides an update on the disease’s aetiology and the future of NPC treatments with a focus on therapies activating T cell immunity.

Increasing incidence of Epstein-Barr virus-related nasopharyngeal carcinoma in the United States

BACKGROUND

The incidence of nasopharyngeal carcinoma (NPC) has been historically low in the United States. Although etiological factors differ by histological subtype, Epstein-Barr virus is accepted as the primary risk factor for nonkeratinizing NPC. In light of the changing epidemiology of viral-associated cancers, it is important to evaluate the temporal incidence of NPC in the United States.

METHODS

Incidence and survival data from 1973 through 2015 were obtained from the Surveillance, Epidemiology, and End Results program. Stratified analyses were conducted to assess temporal trends in NPC by histological subtype, sex, and race. The data were analyzed using SAS and Joinpoint Regression Software to determine age-adjusted incidence rates, determine trends in the annual percent change, and calculate 5-year relative survival estimates and Kaplan-Meier curves.

RESULTS

Although overall NPC incidence is decreasing in the United States, the nonkeratinizing differentiated subtype is starkly increasing, with an annual percent change of approximately 4% among white males (95% CI, 2.5%-5.2%), white females (95% CI, 1.9%-6.2%), and black males (95% CI, 2.0%, 5.7%); 2.7% among black females (95% CI, 0.8%, 4.6%); and 1.8% among women in the "other" race category (95% CI, 0.4%-3.3%). Racial disparities were noted, with 32% of nonkeratinizing NPC cases among blacks occurring before the age of 40 years. In addition, black males displayed consistently worse survival across all histological subtypes, whereas individuals in the "other" race category, particularly females, experienced the highest 5-year relative survival estimates.

CONCLUSIONS

The current results indicate that the Epstein-Barr virus-related, differentiated NPC subtype is increasing across all sexes and races in the United States, with distinct incidence and survival disparities among blacks.

Past and Recent Salted Fish and Preserved Food Intakes Are Weakly Associated with Nasopharyngeal Carcinoma Risk in Adults in Southern China

BACKGROUND

Chinese-style salted fish intake in early life is considered an established risk factor for nasopharyngeal carcinoma (NPC). However, results for adult intakes of salted fish and preserved foods are inconsistent.

OBJECTIVE

The aim of this study was to ascertain the relations of Chinese-style hard and soft salted fish and preserved food intakes with NPC risk.

METHODS

We conducted a population-based case-control study in southern China with 2554 NPC cases identified through a rapid case ascertainment system and 2648 healthy controls, frequency-matched on age, sex, and area. Subjects (aged 20-74 y) were interviewed via a food-frequency questionnaire, including information on portion size. Data were also collected on alcohol consumption and potential confounders. Food intake was grouped into 3-5 energy-adjusted intake levels during adulthood (10 y prior) and adolescence (16-18 y). For childhood (at age 10 y), intake frequency of selected food items was collected. Multivariate-adjusted ORs with 95% CIs were estimated via logistic regression.

RESULTS

We found no association between NPC and intake of hard Chinese-style salted fish during adulthood, and an increased risk at the highest level of intake during adolescence (OR: 1.19; 95% CI: 1.03, 1.39). In contrast, we found a decreased risk for the middle intake level of soft salted fish during adulthood (OR: 0.68; 95% CI: 0.57, 0.81) and adolescence (OR: 0.71; 95% CI: 0.59, 0.85). Preserved foods showed contrasting risk profiles, e.g., the highest adult intake level of salted egg (OR: 1.51; 95% CI: 1.22, 1.87) and fermented black beans (OR: 0.67; 95% CI: 0.56, 0.80). Associations with NPC were weaker than previously reported, e.g., for weekly childhood intake of salted fish (OR: 1.56; 95% CI: 1.24, 1.97).

CONCLUSIONS

Hard and soft salted fish have different risk profiles. Salted fish and other preserved foods were at most weak risk factors for NPC in all periods and may play a smaller role in NPC occurrence than previously thought.

Red Meat and Processed Meat Consumption and Nasopharyngeal Carcinoma Risk: A Dose-response Meta-analysis of Observational Studies

The purpose of this study is to clarify and quantify the potential dose-response association between the intake of total red and total processed meat and risk of nasopharyngeal carcinoma (NPC). Relevant studies were identified by searching PubMed, EMBASE, and Chinese databases (CNKI and Wanfang). The summary relative risk (RR) with 95% confidence interval (95%CI) was calculated. A total of 15 independent studies with 12,735 subjects were identified. Compared with the low-rank intake, the summary RR of NPC was 1.35 (95%CI, 1.21-1.51) for total red meat and 1.46 (95%CI, 1.34-1.64) for total processed meat. For the moderate-rank intake, the summary RR of NPC was 1.54 (95%CI, 1.36-1.79) for total red meat and 1.59 (95%CI, 1.3-1.90) for total processed meat. The summary RR for high-rank intake was 1.71 (95%CI, 1.14-2.55) for total red meat and 2.11 (95%CI, 1.31-3.42) for total processed meat. The combined estimates showed obvious evidence of statistically significant association between total red and total processed meat consumption dose and risk of NPC (Ptrend< 0.01). In conclusion, our data suggest that a high intake of total red or total processed meat is associated with a significantly increased risk of NPC.

Usefulness of IGF-1 serum levels as diagnostic marker of nasopharyngeal carcinoma

BACKGROUND

The role of IGF-1 in promoting cancer has been investigated for many years. The aim of this study is to explore the relationship between rates of IGF-1 and NPC and to evaluate association of IGF-1 with clinical parameters.

MATERIALS AND METHODS

IGF-1 levels was measured by Elisa test among 82 NPC patients and 60 healthy controls

RESULTS

Our results showed, for the first time, a significant increased levels of IGF-I in NPC by in comparison with healthy controls (p<0.01). According to the age, sex and tumor size of NPC patients, we demonstrated that IGF-1 concentrations are significantly higher in NPC aged over 30 years compared to patients aged less than 30 years (p<0.01). The IGF-1 levels are, also, higher among women compared to men (p<0.01). The concentrations of IGF-1 were positively correlated with tumor size of NPC patients (p<0.01).

CONCLUSION

IGF-I could be a good nasopharyngeal cancer diagnostic marker.

Association of soil arsenic and nickel exposure with cancer mortality rates, a town-scale ecological study in Suzhou, China

Heavy metals and arsenic are well-known carcinogens. However, few studies have examined whether soil heavy metals and arsenic concentrations associate with cancer in the general population. In this ecological study, we aimed to evaluate the association of heavy metals and arsenic in soil with cancer mortality rates during 2005-2010 in Suzhou, China, after controlling for education and smoking prevalence. In 2005, a total of 1683 soil samples with a sampling density of one sample every 4 km(2) were analyzed. Generalized linear model with a quasi-Poisson regression was applied to evaluate the association between town-scale cancer mortality rates and soil heavy metal concentrations. Results showed that soil arsenic exposure had a significant relationship with colon, gastric, kidney, lung, and nasopharyngeal cancer mortality rates and soil nickel exposure was significantly associated with liver and lung cancer. The associations of soil arsenic and nickel exposure with colon, gastric, kidney, and liver cancer in male were higher than those in female. The observed associations of soil arsenic and nickel with cancer mortality rates were less sensitive to alternative exposure metrics. Our findings would contribute to the understanding of the carcinogenic effect of soil arsenic and nickel exposure in general population.

Household air pollution and cancers other than lung: a meta-analysis

Household air pollution (HAP) from solid fuel combustion contributes to 2.6% of the global burden of disease. HAP emissions are an established lung carcinogen; however, associations with other cancer sites have not been fully explored. We conducted a meta-analysis of 18 case-control studies. Using fixed-effects models, utilizing the adjusted odds ratios (OR) and 95% confidence intervals (95% CI) from each study, we evaluated the association between HAP and cervical neoplasia (663 cases and 1747 controls) and upper aero-digestive tract cancers (6022 cases and 15 325 controls). We found that HAP was associated with cervical neoplasia (OR = 6.46; 95% CI = 3.12-13.36; 4 studies); oral (OR = 2.44; 95% CI = 1.87-3.19; 4 studies; 1000 cases/3450 controls); nasopharyngeal (OR = 1.80; 95% CI = 1.42-2.29; 6 studies; 2231 cases/2160 controls); pharyngeal (OR = 3.56; 95% CI = 2.22-5.70; 4 studies; 1036 cases/3746 controls); and laryngeal (OR = 2.35; 95% CI = 1.72- 3.21; 5 studies; 1416 cases/4514 controls) cancers. The elevated risk for esophageal cancer (OR = 1.92; 95% CI = 0.82-4.49; 2 studies; 339 cases/1455 controls) was non-significant. HAP was associated with cervical neoplasia among studies that accounted for HPV infection (OR = 9.60; 95% CI = 3.79-24.32) and smoking (OR = 4.72; 95% CI = 1.84-12.07). Similarly, our observed associations between HAP and upper aero-digestive tract cancers remained significantly elevated when analyses were restricted to studies that controlled for smoking. No significant publication bias was detected. Our results suggest that the carcinogenic effect of HAP observed for lung cancer may extend to other cancers, including those of the cervix and the upper aero-digestive tract. Further research is needed to confirm these associations in prospective studies.

Nasopharyngeal Carcinoma: An Evolving Role for the Epstein-Barr Virus

The Epstein-Barr herpesvirus (EBV) is an important human pathogen that is closely linked to several major malignancies including the major epithelial tumor, undifferentiated nasopharyngeal carcinoma (NPC). This important tumor occurs with elevated incidence in specific areas, particularly in southern China but also in Mediterranean Africa and some regions of the Middle East. Regardless of tumor prevalence, undifferentiated NPC is consistently associated with EBV. The consistent detection of EBV in all cases of NPC, the maintenance of the viral genome in every cell, and the continued expression of viral gene products suggest that EBV is a necessary factor for the malignant growth in vivo. However, the molecular characterization of the infection and identification of critical events have been hampered by the difficulty in developing in vitro models of NPC. Epithelial cell infection is difficult in vitro and in contrast to B-cell infection does not result in immortalization and transformation. Cell lines established from NPC usually do not retain the genome, and the successful establishment of tumor xenografts is difficult. However, critical genetic changes that contribute to the onset and progression of NPC and key molecular properties of the viral genes expressed in NPC have been identified. In some cases, viral expression becomes increasingly restricted during tumor progression and tumor cells may express only the viral nuclear antigen EBNA1 and viral noncoding RNAs. As NPC develops in the immunocompetent, the continued progression of deregulated growth likely reflects the combination of expression of viral oncogenes in some cells and viral noncoding RNAs that likely function synergistically with changes in cellular RNA and miRNA expression.

Therapeutic implications of Epstein-Barr virus infection for the treatment of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is highly endemic in certain regions including the People’s Republic of China and Southeast Asia. Its etiology is unique and multifactorial, involving genetic background, epigenetic, and environment factors, including Epstein–Barr virus (EBV) infection. The presence of EBV in all tumor cells, aberrant pattern of antibodies against EBV antigens in patient sera, and elevated viral DNA in patient circulation as well as nasopharyngeal site underline the role of EBV during NPC development. In NPC tumors, EBV expresses latency type II, where three EBV-encoded proteins, Epstein–Barr nuclear antigen 1, latent membrane protein 1 and 2 (LMP1, 2), are expressed along with BamH1-A rightward reading frame 1, Epstein–Barr virus-encoded small nuclear RNAs, and BamH1-A rightward transcripts. Among all encoded proteins, LMP1 plays a central role in the propagation of NPC. Standard treatment of NPC consists of radiotherapy with or without chemotherapy for early stage, concurrent chemoradiotherapy in locally advanced tumors, and palliative systemic chemotherapy in metastatic disease. However, this standard care has limitations, allowing recurrences and disease progression in a certain proportion of cases. Although the pathophysiological link and molecular process of EBV-induced oncogenesis are not fully understood, therapeutic approaches targeting the virus may increase the cure rate and add clinical benefit. The promising results of early phase clinical trials on EBV-specific immunotherapy, epigenetic therapy, and treatment with viral lytic induction offer new options for treating NPC.

Secular trends of salted fish consumption and nasopharyngeal carcinoma: a multi-jurisdiction ecological study in 8 regions from 3 continents

BACKGROUND

Despite salted fish being a classical risk factor of Nasopharyngeal Carcinoma (NPC), whether secular trends in salted fish consumption worldwide accounted for changes in NPC rates were unknown. The relationship between vegetable and cigarette consumption to NPC risk worldwide were also largely uncertain. We investigated the longitudinal trends in standardised NPC incidence/mortality rates across 8 regions and their associations with secular trends in salted fish, vegetable and tobacco consumptions.

METHODS

Age standardised mortality rate (ASMR) and age standardised incidence rate (ASIR) of NPC were obtained from the WHO cancer mortality database and Hong Kong Cancer Registry. Per capita consumption of salted fish, tobacco and vegetables in Hong Kong and 7 countries (China, Finland, Japan, Portugal, Singapore, United Kingdom and United States) were obtained from the Food and Agriculture Organization of the United Nation (FAO) and Hong Kong Trade and Census Statistics. Pearson correlation and multivariate analysis were performed to examine both crude and adjusted associations.

RESULTS

There were markedly decreasing trends of NPC ASIR and ASMR in Hong Kong over the past three decades, which were correlated with corresponding secular changes in salted fish consumption per capita (Pearson r for 10 cumulative years : ASIR = 0.729 (male), 0.674 (female); ASMR = 0.943 (male), 0.622 (female), all p < 0.05 except for female ASMR). However such associations no longer correlated with adjustments for decreasing tobacco and increasing vegetable consumption per capita (Pearson r for 10 cumulative years: ASIR = 2.007 (male), 0.339 (female), ASMR = 0.289 (male), 1.992 (female), all p > 0.05). However, there were no clear or consistent patterns in relations between NPC ASIR and ASMR with salted fish consumption across 7 regions in 3 continents.

CONCLUSIONS

Our results do not support the notion that changes in salted fish consumption had played an important role in explaining secular trends of NPC rates in Hong Kong and worldwide. Further studies should explore other lifestyle and genetic factors. However, our findings do support the potentially protective effects of vegetable consumption against NPC.

Cancer burden in Africa and opportunities for prevention

Cancer is an emerging public health problem in Africa. About 715,000 new cancer cases and 542,000 cancer deaths occurred in 2008 on the continent, with these numbers expected to double in the next 20 years simply because of the aging and growth of the population. Furthermore, cancers such as lung, female breast, and prostate cancers are diagnosed at much higher frequencies than in the past because of changes in lifestyle factors and detection practices associated with urbanization and economic development. Breast cancer in women and prostate cancer in men have now become the most commonly diagnosed cancers in many Sub-Saharan African countries, replacing cervical and liver cancers. In most African countries, cancer control programs and the provision of early detection and treatment services are limited despite this increasing burden. This paper reviews the current patterns of cancer in Africa and the opportunities for reducing the burden through the application of resource level interventions, including implementation of vaccinations for liver and cervical cancers, tobacco control policies for smoking-related cancers, and low-tech early detection methods for cervical cancer, as well as pain relief at the palliative stage of cancer.

Traditional Cantonese diet and nasopharyngeal carcinoma risk: a large-scale case-control study in Guangdong, China

BACKGROUND

Nasopharyngeal carcinoma (NPC) is rare in most parts of the world but is a common malignancy in southern China, especially in Guangdong. Dietary habit is regarded as an important modifier of NPC risk in several endemic areas and may partially explain the geographic distribution of NPC incidence. In China, rapid economic development during the past few decades has changed the predominant lifestyle and dietary habits of the Chinese considerably, requiring a reassessment of diet and its potential influence on NPC risk in this NPC-endemic area.

METHODS

To evaluate the association between dietary factors and NPC risk in Guangdong, China, a large-scale, hospital-based case-control study was conducted. 1387 eligible cases and 1459 frequency matched controls were recruited. Odds ratios (ORs) and the corresponding 95% confidence intervals (CIs) were estimated using a logistic regression model, adjusting for age, sex, education, dialect, and habitation household type.

RESULTS

Observations made include the following: 1) consumption of canton-style salted fish, preserved vegetables and preserved/cured meat were significantly associated with increased risk of NPC, with enhanced odds ratios (OR) of 2.45 (95% CI: 2.03-2.94), 3.17(95% CI: 2.68-3.77) and 2.09 (95% CI: 1.22-3.60) respectively in the highest intake frequency stratum during childhood; 2) consumption of fresh fruit was associated with reduced risk with a dose-dependent relationship (p = 0.001); and 3) consumption of Canton-style herbal tea and herbal slow-cooked soup was associated with decreased risk, with ORs of 0.84 (95% CI: 0.68-1.03) and 0.58 (95% CI: 0.47-0.72) respectively in the highest intake frequency stratum. In multivariate analyses, these associations remained significant.

CONCLUSIONS

It can be inferred that previously established dietary risk factors in the Cantonese population are still stable and have contributed to the incidence of NPC.

Haplotype-dependent HLA susceptibility to nasopharyngeal carcinoma in a Southern Chinese population

We have conducted a comprehensive case-control study of a nasopharyngeal carcinoma (NPC) population cohort from Guangxi Province of Southern China, a region with one of the highest NPC incidences on record. A total of 1407 individuals including NPC patients, healthy controls, and their adult children were examined for the human leukocyte antigen (HLA) association, which is so far the largest NPC cohort reported for such studies. Stratified analysis performed in this study clearly demonstrated that while NPC protection is associated with independent HLA alleles, most NPC susceptibility is strictly associated with HLA haplotypes. Our study also detected for the first time that A(*)0206, a unique A2 subtype to South and Southeast Asia is also associated with a high risk for NPC. HLA-A(*)0206, HLA-B(*)3802 alleles plus the A(*)0207-B(*)4601 and A(*)3303-B(*)5801 haplotypes conferred high risk for NPC showing a combined odds ratio (OR) of 2.6 (P<0.0001). HLA alleles that associate with low risk for NPC include HLA-A(*)1101, B(*)27, and B(*)55 with a combined OR of 0.42 (P<0.0001). The overall high frequency of NPC-susceptible HLA factors in the Guangxi population is likely to have contributed to the high-NPC incidence in this region.

Cannabis, tobacco and domestic fumes intake are associated with nasopharyngeal carcinoma in North Africa

Background:

The lifestyle risk factors for nasopharyngeal carcinoma (NPC) in North Africa are not known.

Methods:

From 2002 to 2005, we interviewed 636 patients and 615 controls from Algeria, Morocco and Tunisia, frequency-matched by centre, age, sex, and childhood household type (urban/rural). Conditional logistic regression was used to evaluate the association of lifestyles with NPC risk, controlling for socioeconomic status and dietary risk factors.

Results:

Cigarette smoking and snuff (tobacco powder with additives) intake were significantly associated with differentiated NPC but not with undifferentiated carcinoma (UCNT), which is the major histological type of NPC in these populations. As demonstrated by a stratified permutation test and by conditional logistic regression, marijuana smoking significantly elevated NPC risk independently of cigarette smoking, suggesting dissimilar carcinogenic mechanisms between cannabis and tobacco. Domestic cooking fumes intake by using kanoun (compact charcoal oven) during childhood increased NPC risk, whereas exposure during adulthood had less effect. Neither alcohol nor shisha (water pipe) was associated with risk.

Conclusion:

Tobacco, cannabis and domestic cooking fumes intake are risk factors for NPC in western North Africa.

HSP70 and mucin 5B: novel protein targets of N,N'-dinitrosopiperazine-induced nasopharyngeal tumorigenesis

N,N'-Dinitrosopiperazine (DNP) induces nasopharyngeal carcinoma (NPC) and shows organ specificity to the nasopharyngeal epithelium. To investigate its mechanism, the rat NPC model was induced using DNP. Rat NPC and normal nasopharyngeal cells were obtained from the NPC model using laser capture. The total proteins from these cell samples were separated with two-dimension polyacrylamide gel electrophoresis techniques, and highly expressed proteins (> five-fold) were analyzed using matrix-assisted laser desorption/ionization time of flight and bioinformatics. The results showed that HSP70 and mucin 5B expression increased not only in rat NPC but also in atypical hyperplasia nasopharyngeal tissues, a precancer stage of NPC. High-expression of heat shock protein 70 (HSP70) and mucin 5B was further supported by western blot analysis. The immunofluorescence and western-blotting studies further showed that DNP induced the expression of HSP70 and mucin 5B in a dosage-dependent manner in normal nasopharyngeal epithelia cells. Our data indicate that DNP triggers over-expression of HSP70 and mucin 5B, and is involved in nasopharyngeal tumorigenesis. HSP70 and mucin 5B may be important targets in nasopharyngeal tumorigenesis induced by DNP.

Safety assessment of coriander (Coriandrum sativum L.) essential oil as a food ingredient

Coriander essential oil is used as a flavor ingredient, but it also has a long history as a traditional medicine. It is obtained by steam distillation of the dried fully ripe fruits (seeds) of Coriandrum sativum L. The oil is a colorless or pale yellow liquid with a characteristic odor and mild, sweet, warm and aromatic flavor; linalool is the major constituent (approximately 70%). Based on the results of a 28 day oral gavage study in rats, a NOEL for coriander oil is approximately 160 mg/kg/day. In a developmental toxicity study, the maternal NOAEL of coriander oil was 250 mg/kg/day and the developmental NOAEL was 500 mg/kg/day. Coriander oil is not clastogenic, but results of mutagenicity studies for the spice and some extracts are mixed; linalool is non-mutagenic. Coriander oil has broad-spectrum, antimicrobial activity. Coriander oil is irritating to rabbits, but not humans; it is not a sensitizer, although the whole spice may be. Based on the history of consumption of coriander oil without reported adverse effects, lack of its toxicity in limited studies and lack of toxicity of its major constituent, linalool, the use of coriander oil as an added food ingredient is considered safe at present levels of use.

Childhood cancer in Sudan: 1999–2007

There is paucity of information on childhood cancer from Sudan with the last studies published more than 20 years ago. This study aims to provide a current picture of childhood cancer in Sudan. Data was obtained from the hospital registry for the period May 1999 to June 2007 on all paediatric patients presenting to the Institute of Nuclear Medicine and Oncology, University of Gezira, Wad Madani, Sudan. There were 322 children with cancer during this time period with a male:female ratio of 1.6:1. Lymphomas (111, 35%), leukaemia (83, 26%) and Wilms' tumour (43, 13%) were the three most common groups of tumours. Thirty percent of all lymphomas were Burkitt's lymphoma; 3.4% of all childhood cancer cases were nasopharyngeal carcinomas.

Dietary risk factors for nasopharyngeal carcinoma in Maghrebian countries

North Africa is one of the major Nasopharyngeal Carcinoma (NPC) endemic regions. Specific food items unique to this area were implicated to be associated with NPC risk, but results were inconsistent. Here we have performed a large-scale case-control study in the Maghrebian population from Tunisia, Algeria and Morocco. From 2002 to 2005, interviews were conducted on 636 cases and 615 controls. Controls were hospitalized individuals from 15 non-cancer hospital departments, or friends and family members of non-NPC cancer subjects, matched by center, childhood household type (rural or urban), age and sex. Conditional logistic regression is used to evaluate the risk of factors. In results, consumption of rancid butter, rancid sheep fat and preserved meat not spicy (mainly quaddid) were associated with significantly increased risk of NPC, while consumption of cooked vegetables and industrial preserved fish was associated with reduced risk. Other foods such as fresh citrus fruits and spicy preserved meat (mainly osban) in childhood, industrial made olive condiments in adulthood, were marginally associated. In multivariate analyses, only rancid butter, rancid sheep fat and cooked vegetables were significantly associated with NPC. In regard to possible causative substances, our results implicate the involvement of butyric acid, a potential Epstein-Barr virus (EBV) activator.

TAP1 gene polymorphisms and nasopharyngeal carcinoma risk in a Tunisian population

To find out whether polymorphisms 333-Ile/Val and 637-Asp/Gly of the transporter part of the antigen processing 1 gene (TAP1) are associated with the development of nasopharyngeal carcinoma (NPC), we studied a total of 374 subjects (209 patients and 165 controls). We used the amplification refractory mutation system polymerase chain reaction (ARMS-PCR) method for analyzing the TAP1 gene polymorphisms. We found a significant difference between the patients and the controls in both the TAP1 codon 333 and codon 637 (P = 0.009 and P = 0.002, respectively). We also found that genotypes with the A allele were present in 206 patients with NPC and 155 controls (98.5 vs. 93.9%; P = 0.032; OR = 4.43) and that genotypes with the B allele were more often present in the control group (45 vs. 32%; P = 0.004; OR = 0.48), suggesting a significant positive association of the A allele with NPC risk and a protective role of the B allele. We have observed an association between the distribution of TAP1 alleles and the NPC patient's age at onset, compared with controls. These results back up the fact that the etiology of NPC in intermediate-risk countries is completely different in each peak of age prevalence and that each peak may possess its own particular oncogenic mechanism.

Second primary cancers in patients with nasopharyngeal carcinoma: a pooled analysis of 13 cancer registries

OBJECTIVE

To study the risk of second primary cancers in nasopharyngeal carcinoma (NPC) patients and the risk of NPC as second primary cancer.

METHODS

We used data from the cancer registries from Singapore and from 12 low-incidence areas, including a total of 8,947 first occurring NPC cases, and 167 second occurring cases. We calculated standardized incidence ratios (SIRs) by comparing the second cancer incidence in NPC patients to the first primary cancer incidence in non-cancer population. We also calculated SIRs of second NPC after other primaries.

RESULTS

In Singapore, the risk of cancers of the lung (SIR=0.42), stomach (SIR=0.41), and colon (SIR=0.23) was significantly decreased after NPC, whereas that of cancer of the tongue (SIR=11.1) was significantly increased. In Australia, Canada, and Europe, the risk of non-Hodgkin's lymphoma (NHL) (SIR=3.06), tongue cancer (SIR=5.29), brain cancer (SIR=3.89), myeloid leukemia (SIR=3.85), and non-melanoma skin cancer (NMSC) (SIR=3.47) was significantly increased after NPC. Incidences of second occurring NPCs following various primary cancers were not significantly altered compared to the incidence of first occurring NPCs.

CONCLUSIONS

Immune suppression (NHL, NMSC), shared genetic factors (lung cancer, NHL, myeloid leukemia), and shared environmental risk factors (tongue and brain cancers) might explain the associations. Except for NHL, there was no evidence of association with other Epstein-Barr virus-related cancers.

Genetic factors leading to chronic Epstein-Barr virus infection and nasopharyngeal carcinoma in South East China: study design, methods and feasibility

Nasopharyngeal carcinoma (NPC) is a complex disease caused by a combination of Epstein-Barr virus chronic infection, the environment and host genes in a multi-step process of carcinogenesis. The identity of genetic factors involved in the development of chronic Epstein-Barr virus infection and NPC remains elusive, however. Here, we describe a two-phase, population-based, case-control study of Han Chinese from Guangxi province, where the NPC incidence rate rises to a high of 25-50 per 100,000 individuals. Phase I, powered to detect single gene associations, enrolled 984 subjects to determine feasibility, to develop infrastructure and logistics and to determine error rates in sample handling. A microsatellite screen of Phase I study participants, genotyped for 319 alleles from 34 microsatellites spanning an 18-megabase region of chromosome 4 (4p15.1-q12), previously implicated by a linkage analysis of familial NPC, found 14 alleles marginally associated with developing NPC or chronic immunoglobulin A production (p = 0.001-0.03). These associations lost significance after applying a correction for multiple tests. Although the present results await confirmation, the Phase II study population has tripled patient enrolment and has included environmental covariates, offering the potential to validate this and other genomic regions that influence the onset of NPC.

The enigmatic epidemiology of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) has a unique and complex etiology that is not completely understood. Although NPC is rare in most populations, it is a leading form of cancer in a few well-defined populations, including natives of southern China, Southeast Asia, the Arctic, and the Middle East/North Africa. The distinctive racial/ethnic and geographic distribution of NPC worldwide suggests that both environmental factors and genetic traits contribute to its development. This review aims to summarize the current knowledge regarding the epidemiology of NPC and to propose new avenues of research that could help illuminate the causes and ultimately the prevention of this remarkable disease. Well-established risk factors for NPC include elevated antibody titers against the Epstein-Barr virus, consumption of salt-preserved fish, a family history of NPC, and certain human leukocyte antigen class I genotypes. Consumption of other preserved foods, tobacco smoking, and a history of chronic respiratory tract conditions may be associated with elevated NPC risk, whereas consumption of fresh fruits and vegetables and other human leukocyte antigen genotypes may be associated with decreased risk. Evidence for a causal role of various inhalants, herbal medicines, and occupational exposures is inconsistent. Other than dietary modification, no concrete preventive measures for NPC exist. Given the unresolved gaps in understanding of NPC, there is a clear need for large-scale, population-based molecular epidemiologic studies to elucidate how environmental, viral, and genetic factors interact in both the development and the prevention of this disease.

Adulthood consumption of preserved and nonpreserved vegetables and the risk of nasopharyngeal carcinoma: a systematic review

The incidence rates of nasopharyngeal carcinoma (NPC) are dramatically higher in certain regions of Asia compared to the rest of the world. Few risk factors for NPC are known; however, in contrast to the hypothesized health benefits of nonpreserved vegetables, it is thought that preserved vegetable intake may play a role in contributing to the higher incidence of NPC in high-risk regions. Therefore, the purpose of this study was to systematically review the epidemiologic evidence on the associations between adulthood intake of preserved and nonpreserved vegetables and NPC risk. A search of the epidemiological literature from 1966 to 2004 was performed using several bibliographic databases, including PubMed and the Chinese Biomedical Literature Database System. There were no language restrictions. Meta-analysis was conducted to obtain pooled odds ratios (ORs) for the highest-versus-lowest categories of preserved and nonpreserved vegetable intake. A total of 16 case-control studies were identified in the search. Results showed that highest-versus-lowest preserved vegetable intake was associated with a 2-fold increase in the risk of NPC (Random Effects Odds Ratio (RE OR) 2.04; 95% Confidence Limits (CL) 1.43, 2.92). Conversely, high nonpreserved vegetable intake was associated with 36% decrease in the risk of NPC (RE OR 0.64; 95% CL 0.48, 0.85). Findings for both preserved and nonpreserved vegetables were consistent across vegetable type and by country of study. Further research in high-risk areas to gain insight into the risk associated with preserved vegetables and protection associated with nonpreserved vegetables may advance understanding of NPC and yield clues for prevention.

Conventional and array-based comparative genomic hybridization analysis of nasopharyngeal carcinomas from the Mediterranean area

Nasopharyngeal carcinoma (NPC) occurs with a high incidence in Southeast Asia and to a lesser extent in the Mediterranean area, especially in Tunisia, Algeria, and Morocco. Cellular gene alterations combined with latent Epstein-Barr virus infection are thought to be essential for NPC oncogenesis. To date, chromosome analysis with comparative genomic hybridization (CGH) has been reported exclusively for NPCs from Southeast Asia. Although NPCs from the Mediterranean area have several distinct clinical and epidemiological features, CGH investigations have been lacking. Chromosome analysis was therefore undertaken on a series of NPC xenografts and biopsies derived from patients of Mediterranean origin. Four xenografts were investigated with a combination of conventional CGH, array-based CGH, and comparative expressed sequence hybridization. In addition, 23 fresh NPC biopsies were analyzed with conventional CGH. Data obtained from xenografts and fresh biopsies were consistent, except that amplification of genes at 18p was observed only in xenografts derived from metastatic tissues. Frequent gains associated with gene overexpression were detected at 1q25 approximately qter (64%) and 12p13 (50%). Losses were noticed mainly at 11q14 approximately q23 (50%), 13q12 approximately q31 (50%), 14q24 approximately q31 (43%), and 3p13 approximately p23 (43%). Comparison with previous reports suggests that Mediterranean NPCs have higher frequencies of gains at 1q and losses at 13q than their Asian counterparts.

Comparison of three different serological techniques for primary diagnosis and monitoring of nasopharyngeal carcinoma in two age groups from Tunisia

Nasopharyngeal carcinoma (NPC) in Tunisia is characterized by its bimodal age distribution involving juvenile patients of 10-24 years and adult patients of 40-60 years. Three serological techniques were compared for primary diagnosis (N = 117) and post-treatment monitoring (N = 21) of NPC patients separated in two age groups. Immunofluorescence assay (IFA) was used as the "gold standard" for detection of IgG and IgA antibodies reactive with Epstein-Barr virus (EBV) early (EA) and viral capsid (VCA) antigens. Results were compared with ELISA measuring IgG and IgA antibody reactivity to defined EBNA1, EA, and VCA antigens. Immunoblot was used to reveal the molecular diversity underlying the anti-EBV IgG and IgA antibody responses. The results indicate that young NPC patients have significantly more restricted anti-EBV IgG and IgA antibody responses with aberrant IgG VCA/EA levels in 78% compared to 91.7% in elder patients. IgA VCA/EA was detected in 50% of young patients versus 89.4% for the elder group (P < 0.001). Immunoblot revealed a reduced overall diversity of EBV antigen recognition for both IgG and IgA in young patients. A good concordance was observed between ELISA and IFA for primary NPC diagnosis with 81-91% overall agreement. Even better agreement (95-100%) was found for antibody changes during follow-up monitoring, showing declining reactivity in patients in remission and increasing reactivity in patients with persistent disease or relapse. ELISA for IgA anti-VCA-p18 and immunoblot proved most sensitive for predicting tumor relapse. VCA-p18 IgA ELISA seems suitable for routine diagnosis and early detection of NPC complication.

EBV-associated nasopharyngeal carcinomas: from epidemiology to virus-targeting strategies

Nasopharyngeal carcinoma is a human malignancy consistently associated with the Epstein-Barr virus. Exposure to non-viral carcinogens and genetic predisposition are other crucial etiologic factors. Tumor development appears to require the expression of a small subset of transforming viral RNAs and proteins with concomitant silencing of most other viral genes. Impairment of the interactions of viral proteins with cellular partners or disruption of viral latency might prove to be useful for novel therapeutic strategies.

Carcinomes nasopharyngés associés au virus d’Epstein-Barr

Nasopharyngeal carcinomas (NPC) challenge clinicians and biologists in various fields including epidemiology, genetics, virology and immunology. These tumours have a striking geographical distribution. They are constantly associated with the Epstein-Barr virus (EBV) and contain a massive lymphocytic infiltrate. Their study has major implications especially at this moment while a pathological role of EBV is suspected in several other human epithelial malignancies (for example gastric, mammary and thyroid carcinomas). The North-South Workshop on Nasopharyngeal Carcinoma was held at the Institut Gustave-Roussy in early December 2003. Its main goal was to support the exchanges between clinical research on NPC in the South and basic research in the North. With regard to epidemiology and genetics, the main information was the possible existence of several susceptibility genes (including two of them on the 4p and 5p chromosomes). In virology, participants have emphasized the selection of peculiar EBV variants within the malignant cells and the expression of novel oncogenic viral proteins : LMP2 and BARF1. Cellular gene alterations also contribute to NPC development, especially inactivation of tumor suppressor genes located on the 3p chromosome. Therapeutic research was not forgotten. Hope of higher rate of cure relies on improved ballistic processes in radiotherapy (IMRT) and on the development of targeted therapeutics : induction of the lytic/productive viral cycle, gene therapy with conditional replicative adenoviruses, antitumor vaccination directed against the viral protein LMP2.

Epstein-Barr virus seroreactivity among unaffected individuals within high-risk nasopharyngeal carcinoma families in Taiwan

Most adults have been infected with EBV. Many studies have indicated that antibodies against specific EBV antigens, particularly IgA antibodies, can be predictive or prognostic of EBV-associated malignancies, such as NPC. We hypothesized that healthy individuals from families with a history of multiple members affected with NPC (who therefore might be genetically susceptible to NPC themselves) might have an EBV antibody profile that is distinct from that seen in healthy individuals from the community at large. To explore this possibility and examine determinants of anti-EBV antibody levels in healthy, high-risk individuals, we evaluated data from 2 parallel studies of NPC in Taiwan, which included 1,229 healthy members of families in which 2 or more individuals were affected with NPC and 320 controls from the community at large. Blood collected from participants was tested for IgA antibodies against EBV VCA and EBNA-1 and for neutralizing antibodies against EBV DNase using standard assays. We observed evidence of familial aggregation of EBV seroreactivity among individuals from high-risk, multiplex NPC families. Anti-VCA IgA and anti-EBNA-1 IgA antibody seroprevalence in unaffected family members of NPC cases was 5-6 times higher than in members of the community (p < 0.01). This elevated seroprevalence among unaffected individuals from high-risk families was observed regardless of the relationship of the unaffected individual to the closest affected relative (siblings, parents, children or spouses). No sociodemographic or environmental factors examined were found to strongly and consistently correlate with elevated seroprevalence, but patterns emerged of increasing seroprevalence among older individuals and among females. Unaffected individuals from high-risk NPC families have elevated anti-EBV IgA antibody titers. The etiologic and clinical implications of this finding remain to be established.

Nasopharyngeal carcinomas: an update

Among the group of head and neck cancers, nasopharyngeal carcinomas (NPC) represent a distinct entity in terms of their epidemiology, clinical presentation, biological markers, carcinogenic risk factors, prognostic factors, treatment and outcome. Undifferentiated NPC (UCNT), the most frequent histological type, is endemic in certain regions, especially in South East Asia. The disease has also been associated with the presence of the Epstein-Barr Virus (EBV). Although NPC is a radiosensitive and chemosensitive tumour, a substantial number of patients develop local recurrence or distant metastases. For patients with locoregional advanced disease, it is well known that conventional radiotherapy is insufficient in terms of both the local control rates and distant metastases. New techniques of radiation and new combined radiotherapy and chemotherapy modalities have been evaluated in numerous clinical trials in recent years. The purpose of this article is to review the current knowledge in terms of the epidemiology, biology, prognosis, management and outcome of patients with NPC.

The p53 codon 72 polymorphism in Thai nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a serious cancer in Thailand. To address on the genetic risk factor for NPC, we investigated association between the p53 codon 72 polymorphism (Pro/Arg) and NPC susceptibility in the Thai. The genotype frequency of this polymorphism in 102 NPC patients and 148 age-matched healthy controls was determined by using a PCR-RFLP assay. No statistically significant difference in the overall genotype frequencies or allele frequencies between cases and controls was observed. Among NPC patients, no statistical significant difference in p53 genotype frequencies between sex, histological types and clinical stages was observed. When cases and controls were categorized into 3 groups of age, >40, >45 and >50 years, the frequencies of p53 genotype in the cases were significantly different from those of the controls (P<0.05). The p53 Pro homozygotes with age of >40 years had twofold to threefold higher risk to develop NPC and the risk was increased with age (Odds Ratio (OR) increased from 2.01 to 2.63 by age >40 to >50 years). Individuals of age >40, >45 and >50 years with an Arg/Arg genotype and of age >45 and >50 years with combined Arg/Arg or Arg/Pro genotype had lower risk to develop NPC than those with Pro/Pro genotype (P<0.05). Collectively, we suggest that the p53 gene polymorphism may associate with NPC susceptibility in Thai population, particularly the Pro/Pro genotype carriers with age of >40 years. The detection of this p53 polymorphism may be a useful tool for screening of early stage and diagnosis of NPC.

Polymeric immunoglobulin receptor polymorphisms and risk of nasopharyngeal cancer

BACKGROUND

Epstein-Barr virus (EBV) associated nasopharyngeal cancer (NPC) is an important squamous cell cancer endemic in Southeast Asia and the Far East and can be considered a multifactorial genetic disease. This research explores potential associations between nasopharyngeal epithelial EBV receptor and NPC susceptibility. To prove the hypothesis, we evaluated two candidate genes, complement receptor 2 (CR2) and polymeric immunoglobulin receptor (PIGR) by using 4 SNPs, CR2IVS2-848C-->T, PIGRIVS3-156G-->T, PIGR1093G-->A and PIGR1739C-->T, to genotype 175 cases and 317 controls, divided into Thai, Chinese and Thai-Chinese based on their respective ethnic origins.

RESULTS

The results obtained indicated that PIGR is an NPC susceptibility gene. The risk association pertaining to each ethnic group was detected for homozygous PIGR1739C with a significant ethnic group adjusted OR (95%CI) of 2.71(1.72-4.23) and p < 0.00001. Haplotype of the two missense PIGR SNPs, 1093G-->A and 1739C-->T, and sequence analyses have confirmed the role of the nucleotide PIGR1739 and excluded possibility of an additional significant nonsynonymous NPC susceptibility SNP.

CONCLUSIONS

We present genetic evidence leading to hypothesize a possibility of PIGR to function as the EBV nasopharyngeal epithelium receptor via IgA-EBV complex transcytosis failure. The PIGR1739C-->T is a missense mutation changing alanine to valine near endoproteolytic cleavage site. This variant could alter the efficiency of PIGR to release IgA-EBV complex and consequently increase the susceptibility of populations in endemic areas to develop NPC.

Epidemiology of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a rare malignancy in most parts of the world, with an incidence well under 1 per 100,000 person-years. Exceptions are the Chinese, especially the Cantonese living in the central region of Guangdong Province in Southern China. Other populations with elevated rates include the natives of Southeast Asia, the natives of the Artic region, and the Arabs of North Africa and parts of the Middle East. Intake of preserved foods at an early age has been linked to NPC risk in all population groups with increased NPC rates. Other recognized risk factors for NPC are cigarette smoking, and occupational exposure to formaldehyde and wood dust.

The aetiology of nasopharyngeal carcinoma

Nasopharyngeal carcinoma is a disease with a remarkable racial and geographical distribution. In most parts of the world it is a rare condition and in only a handful of places does this low risk profile alter. These include the Southern Chinese, Eskimos and other Arctic natives, inhabitants of South-East Asia and also the populations of North Africa and Kuwait.

Epstein-barr virus-associated malignancies: epidemiologic patterns and etiologic implications

Epstein-Barr virus (EBV), a ubiquitous B-lymphotrophic herpesvirus, has been found in the tumor cells of a heterogeneous group of malignancies (Burkitt's lymphoma, lymphomas associated with immunosuppression, other non-Hodgkin's lymphomas, Hodgkin's disease, nasopharyngeal carcinoma, gastric adenocarcinoma, lymphoepithelioma-like carcinomas, and immunodeficiency-related leiomyosarcoma). As the epidemiologic characteristics of these cancers have not been considered together, this review seeks to relate their incidence patterns and risk factors to EBV biology and virus-host interaction in an attempt to help elucidate factors involved in EBV-related carcinogenesis. We include a brief review of EBV virology and primary infection to provide a biologic context for considering the epidemiology, summarize the most salient epidemiologic features of each malignancy, synthesize epidemiologic data by risk factor to uncover commonalities and informative contrasts across the diseases, and propose hypotheses regarding etiologic mechanisms, based on the possible effect of the risk factors at various stages in the viral life cycle.

Preserved foods in relation to risk of nasopharyngeal carcinoma in Shanghai, China

A population-based case-control study was conducted in Shanghai, China, to investigate the association between dietary factors and risk of nasopharyngeal carcinoma (NPC). The study included 935 NPC patients aged 15 to 74 years and 1,032 community controls. Exposures to salted fish and other protein-containing preserved food were associated with increased risk of NPC. Individuals who ate salted fish at least once a week had an 80% increase in risk of NPC relative to those who ate salted fish less than once a month (p = 0.07). Compared with those in the lowest quartile of protein-containing preserved foods, subjects in the highest quartile of intake experienced a statistically significant 78% increase in risk of NPC [odds ratio (OR) = 1.78, 95% confidence interval (CI) = 1.37-2.31], with a dose-dependent relationship (p for linear trend < 0.001 ). A similar association between intake of preserved vegetables and NPC risk was observed (OR = 1.39, p for linear trend = 0.003). In contrast, high intake of oranges/tangerines was associated with a statistically significant reduction in risk of NPC (OR = 0.55, p for linear trend < 0.001). When we examined the joint effect of preserved food and oranges/tangerines on risk of NPC, subjects in the highest tertile of preserved food and the lowest tertile of orange/ tangerine intake had a 3-fold increase in risk (95% CI = 2.08-4.91) compared with those in the lowest tertile of preserved food and the highest tertile of orange/tangerine intake.

Dietary nitrates, nitrites, and N-nitroso compounds and cancer risk: a review of the epidemiologic evidence

Experimental animal studies have shown N-nitroso compounds (NOC) to be potent carcinogens. Epidemiologic evidence of the carcinogenic potential of dietary NOC and precursor nitrates and nitrites in humans remains inconclusive with regard to the risk of stomach, brain, esophageal, and nasopharyngeal cancers. Inadequate available data could obscure a small to moderate effect of NOC.

A case-control study of risk factors of nasopharyngeal carcinoma

Risk factors and nasopharyngeal carcinoma (NPC) in residents of Guangzhou city were investigated in a case-control study: 104 cases were compared with an equal number of age, sex, and neighborhood-matched controls. The results of multiple conditional regression of logistic model showed that plum vegetable (adjusted OR = 1.81, 95% CI 1.01-3.33), preserved prune (adjusted OR = 2.95, 95% CI 1.04-8.41), no separate kitchen (if >35 years, adjusted OR = 1.98, 95% CI 1.24-3.75), kitchen range without chimney (if >10 years, adjusted OR = 2.72, 95% CI 1.56-4.73) and hereditary factor (adjusted OR = 8.27, 95% CI 1.94-35.54) were significantly associated with an increased risk of NPC. Grape (adjusted OR = 0.31, 95% CI 0.17-0.58) may be a protective factor.

Sister chromatid exchanges induced in vitro and in vivo by an extract of black pepper

Black pepper is a spice widely used in human food. The aim of this investigation was to determine whether an alcoholic extract of the mature berries of black pepper induced genotoxic damage in vivo and in vitro. The first aspect was evaluated in mouse bone marrow cells and the second one in human lymphocytes. In both cases the rate of sister chromatid exchange (SCE) and the replicative index were determined. For the in vivo assay, ip doses of 7.0, 14.0, 28.0 and 56.0 mg/kg body weight were tested, with the following results: (1) a significant increase of SCE frequency in all doses tested compared with the control level (the highest dose produced almost a duplication of the basal rate of SCEs); (2) a similar pattern with regard to cell proliferation kinetics at all doses tested, without significant differences between them. For the in vitro assay, doses of 25.0, 50.0, 75.0 and 100.0 micrograms/ml were tested, with the following results: (1) a significant increase in the frequency of SCEs at all doses tested; a linear regression analysis of the data produced a correlation coefficient of 0.98; (2) a significant reduction in the replicative index, at the two high doses. These results demonstrated that the extract of black pepper was genotoxic in both systems.

Evaluation of the aetiological role of dietary salt exposure in gastric and other cancers in humans

The findings in laboratory and epidemiological studies relevant to the assessment of salt for carcinogenic potential are reviewed. Associations between the high consumption of certain highly salted foodstuffs, particularly in some oriental countries, and increased risk of cancer of the stomach do not incriminate salt per se. Some highly spiced foods contain potent genotoxic carcinogens, irrespective of whether they also contain salt. There is evidence in laboratory animals that high concentrations of salt may increase the incidence of gastric cancer caused by such carcinogens. This may well be attributable to a marked and sustained regenerative response in the gastric mucosa of laboratory animals chronically exposed to the cytotoxicity of hyperosmolar concentrations of salt, such a mitogenic response favouring the progression towards neoplasia. However, there is no laboratory evidence whatsoever to indicate that salt per se is a carcinogen for any site in the body; neither is there any reliable epidemiological evidence to indicate that dietary salt affects the incidence of gastric or other cancers. A particular problem in the interpretation of epidemiological studies is that the consumption of diets containing highly salted, spicy foods is often associated with low intakes of fruit and green vegetables, which contain cancer-protective antioxidants. In Western countries the incidence of cancer of the stomach has been falling for some 50 years. The consensus view is that this fall is attributable to improved food hygiene and increasingly available facilities for refrigeration. There are no grounds for supposing that the fall is attributable to a decreasing intake of salt. A high dietary salt intake does not necessarily entail exposure to salt in concentrations high enough to damage the gastric mucosa. The typical Western diet would not be expected to provide such high salt concentrations. It is concluded that there are no grounds for believing that a reduction in the average daily salt intake in the Western diet would have any effect on the risk of developing any form of cancer.

Role of N-nitroso compounds (NOC) and N-nitrosation in etiology of gastric, esophageal, nasopharyngeal and bladder cancer and contribution to cancer of known exposures to NOC

The questions of whether and how N-nitroso compounds (NOC) may be inducing cancer in humans are discussed. The principal subjects covered include nitrite-derived alkylating agents that are not NOC, reasons for the wide tissue specificity of carcinogenesis by NOC, the acute toxicity of nitrosamines in humans, mechanisms of in vivo formation of NOC by chemical and bacterial nitrosation in the stomach and via nitric oxide (NO) formation during inflammation, studies on nitrite esters, use of the nitrosoproline test to follow human gastric nitrosation, correlations of nitrate in food and water with in vivo nitrosation and the inhibition of gastric nitrosation by vitamin C and polyphenols. Evidence that specific cancers are caused by NOC is reviewed for cancer of the stomach, esophagus, nasopharynx, urinary bladder in bilharzia and colon. I review the occurrence of nitrosamines in tobacco products, nitrite-cured meat (which might be linked with childhood leukemia and brain cancer) and other foods, and in drugs and industrial situations. Finally, I discuss clues from mutations in ras and p53 genes in human tumors about whether NOC are etiologic agents and draw some general conclusions.