Jasmine tea consumption and upper gastrointestinal cancer in China. Cancer Causes Control. 2009;20:1997-2007. [PMID: 19597950 DOI: 10.1007/s10552-009-9394-z]

Overview of Risk Factors for Esophageal Squamous Cell Carcinoma in China

(1) Background: China has the highest esophageal squamous cell carcinoma (ESCC) incidence areas in the world, with some areas of incidence over 100 per 100,000. Despite extensive public health efforts, its etiology is still poorly understood. This study aims to review and summarize past research into potential etiologic factors for ESCC in China. (2) Methods: Relevant observational and intervention studies were systematically extracted from four databases using key terms, reviewed using Rayyan software, and summarized into Excel tables. (3) Results: Among the 207 studies included in this review, 129 studies were focused on genetic etiologic factors, followed by 22 studies focused on dietary-related factors, 19 studies focused on HPV-related factors, and 37 studies focused on other factors. (4) Conclusions: ESCC in China involves a variety of factors including genetic variations, gene-environment interactions, dietary factors like alcohol, tobacco use, pickled vegetables, and salted meat, dietary behavior such as hot food/drink consumption, infections like HPV, poor oral health, gastric atrophy, and socioeconomic factors. Public health measures should prioritize genetic screening for relevant polymorphisms, conduct comprehensive investigations into environmental, dietary, and HPV influences, enhance oral health education, and consider socioeconomic factors overall as integral strategies to reduce ESCC in high-risk areas of China.

Orthonasal olfactory influences on consumer food behaviour

It is often suggested in the popular press that food chains deliberately introduce enticing product aromas into (and in the immediate vicinity of) their premises in order to attract customers. However, despite the widespread use of odours in the field of sensory marketing, laboratory research suggests that their effectiveness in modulating people's food behaviours depends on a range of contextual factors. Given the evidence that has been published to date, only under a subset of conditions is there likely to be a measurable effect of the presence of ambient odours on people's food attitudes and choices. This narrative historical review summarizes the various ways in which food odours appear to bias people's food preferences (appetite) and food choices (food consumption and purchase). Emphasis is placed on those experimental studies that have been designed to investigate how the characteristics of the olfactory stimuli (e.g., the congruency between the olfactory cues and the foods, intensity and duration of exposure to odours, and taste properties of odours) modulate the effects of olfactory cues on food behaviour. The review also explores the moderating roles of individual differences, such as dietary restraint, Body Mass Index (BMI), genetic and cultural differences in odour sensitivity and perception. Ultimately, following a review of empirical studies on food-related olfaction, current approaches in scent marketing are discussed and a research agenda is proposed to help encourage further studies on the effective application of scents in promoting healthy foods.

Green tea consumption and risk for esophageal cancer: A systematic review and dose-response meta-analysis

OBJECTIVE

Controversial results of the association between green tea consumption and risk for esophageal cancer (EC) were reported by previous meta-analysis. Thus, the aim of this study was to quantitatively investigate the association.

METHODS

The Cochrane Library, PubMed, and EMBASE databases were searched for relevant studies. We used a "one-stage approach" with a restricted cubic spline model to summarize the dose-specific relationships between green tea and risk for EC. Odds ratios (ORs) were used to measure the effects. Fourteen studies were included with a total of 5057 ECs among 493 332 participants.

RESULTS

In the dose-response analysis, the summary OR for a 1 cup/d increase in green tea was 1.00 (95% confidence interval [CI], 0.95-1.04; I² = 77%). No nonlinearity association was observed between tea consumption and risk for EC (P = 0.71 for nonlinearity). In the subgroup of sex, the summary OR for a 1 cup/d increase in green tea was 1.03 (95% CI, 0.95-1.11, I² = 67%) for men and 0.79 (95% CI, 0.68-0.91; I² = 0%) for women.

CONCLUSION

Contrary to previous studies, based on current evidence, the present dose-response study suggested no association between green tea and risk for EC. However, there might be a protective effect of green tea in women. Notably, our conclusion might be influenced by limited studies and potential bias, such as dose of green tea assessment and select bias of case-control studies. Further larger number, prospective, and well-designed larger-scale studies are needed to provide more precise evidence, especially in women and more regions (United States and Europe).

Tea drinking and the risk of esophageal cancer: focus on tea type and drinking temperature

The association between tea drinking and esophageal cancer is still contradictory. This study is to determine the association between tea drinking and esophageal squamous cell carcinoma focusing on drinking temperature and tea types. A population-based case-control study was conducted in a high esophageal squamous cell carcinoma risk area in China. A total of 942 incident esophageal squamous cell carcinoma cases with historical confirmation and 942 age- and sex- individually matched community controls were recruited from the study area. Trained interviewers using a structured questionnaire collected detailed information on tea drinking, diet, smoking and alcohol drinking habits. Habitual tea drinking temperature was measured with a thermometer during interviews. We analyzed the association between tea consumption, drinking temperature and esophageal squamous cell carcinoma, stratified by tea type, while adjusting for other potentially confounding factors. Drinking very hot tea (>65°C) was significantly associated with the increased risk of esophageal squamous cell carcinoma (odds ratio = 1.67, 95% confidential interval 1.25-2.24) relative to non-drinkers. Consumption of black tea, irrespective of the frequency, intensity and tea leaf amount, was significantly associated with a higher risk (P for trend <0.01). Compared to those who consumed <300 g/month tea leaves at ≤65°C, those who consumed more than 300 g/month tea leave at >65°C had a more than 1.8-fold higher risk of esophageal squamous cell carcinoma for both green tea and black tea. Our results provide more evidence that drinking very hot tea (above 65°C) are significantly associated with an increased risk of esophageal squamous cell carcinoma.

Green tea (Camellia sinensis) for the prevention of cancer

BACKGROUND

This review is an update of a previously published review in the Cochrane Database of Systematic Reviews (2009, Issue 3).Tea is one of the most commonly consumed beverages worldwide. Teas from the plant Camellia sinensis can be grouped into green, black and oolong tea, and drinking habits vary cross-culturally. C sinensis contains polyphenols, one subgroup being catechins. Catechins are powerful antioxidants, and laboratory studies have suggested that these compounds may inhibit cancer cell proliferation. Some experimental and nonexperimental epidemiological studies have suggested that green tea may have cancer-preventative effects.

OBJECTIVES

To assess possible associations between green tea consumption and the risk of cancer incidence and mortality as primary outcomes, and safety data and quality of life as secondary outcomes.

SEARCH METHODS

We searched eligible studies up to January 2019 in CENTRAL, MEDLINE, Embase, ClinicalTrials.gov, and reference lists of previous reviews and included studies.

SELECTION CRITERIA

We included all epidemiological studies, experimental (i.e. randomised controlled trials (RCTs)) and nonexperimental (non-randomised studies, i.e. observational studies with both cohort and case-control design) that investigated the association of green tea consumption with cancer risk or quality of life, or both.

DATA COLLECTION AND ANALYSIS

Two or more review authors independently applied the study criteria, extracted data and assessed methodological quality of studies. We summarised the results according to diagnosis of cancer type.

MAIN RESULTS

In this review update, we included in total 142 completed studies (11 experimental and 131 nonexperimental) and two ongoing studies. This is an additional 10 experimental and 85 nonexperimental studies from those included in the previous version of the review. Eleven experimental studies allocated a total of 1795 participants to either green tea extract or placebo, all demonstrating an overall high methodological quality based on 'Risk of bias' assessment. For incident prostate cancer, the summary risk ratio (RR) in the green tea-supplemented participants was 0.50 (95% confidence interval (CI) 0.18 to 1.36), based on three studies and involving 201 participants (low-certainty evidence). The summary RR for gynaecological cancer was 1.50 (95% CI 0.41 to 5.48; 2 studies, 1157 participants; low-certainty evidence). No evidence of effect of non-melanoma skin cancer emerged (summary RR 1.00, 95% CI 0.06 to 15.92; 1 study, 1075 participants; low-certainty evidence). In addition, adverse effects of green tea extract intake were reported, including gastrointestinal disorders, elevation of liver enzymes, and, more rarely, insomnia, raised blood pressure and skin/subcutaneous reactions. Consumption of green tea extracts induced a slight improvement in quality of life, compared with placebo, based on three experimental studies. In nonexperimental studies, we included over 1,100,000 participants from 46 cohort studies and 85 case-control studies, which were on average of intermediate to high methodological quality based on Newcastle-Ottawa Scale 'Risk of bias' assessment. When comparing the highest intake of green tea with the lowest, we found a lower overall cancer incidence (summary RR 0.83, 95% CI 0.65 to 1.07), based on three studies, involving 52,479 participants (low-certainty evidence). Conversely, we found no association between green tea consumption and cancer-related mortality (summary RR 0.99, 95% CI 0.91 to 1.07), based on eight studies and 504,366 participants (low-certainty evidence). For most of the site-specific cancers we observed a decreased RR in the highest category of green tea consumption compared with the lowest one. After stratifying the analysis according to study design, we found strongly conflicting results for some cancer sites: oesophageal, prostate and urinary tract cancer, and leukaemia showed an increased RR in cohort studies and a decreased RR or no difference in case-control studies.

AUTHORS' CONCLUSIONS

Overall, findings from experimental and nonexperimental epidemiological studies yielded inconsistent results, thus providing limited evidence for the beneficial effect of green tea consumption on the overall risk of cancer or on specific cancer sites. Some evidence of a beneficial effect of green tea at some cancer sites emerged from the RCTs and from case-control studies, but their methodological limitations, such as the low number and size of the studies, and the inconsistencies with the results of cohort studies, limit the interpretability of the RR estimates. The studies also indicated the occurrence of several side effects associated with high intakes of green tea. In addition, the majority of included studies were carried out in Asian populations characterised by a high intake of green tea, thus limiting the generalisability of the findings to other populations. Well conducted and adequately powered RCTs would be needed to draw conclusions on the possible beneficial effects of green tea consumption on cancer risk.

Green Tea Consumption and Esophageal Cancer Risk: A Meta-analysis

Background: The protective role of green tea against cancer is still unknown.Objectives: To investigate the association between green tea consumption and esophageal cancer risk through meta-analysis.Methods: We searched MEDLINE, EMBASE, Web of Science and Cochrane Library for studies on the relationship between green tea and esophageal cancer risk. We assessed heterogeneity (I²) and publication bias (Begg's and Egger's tests). Pooled relative risks (RRs) or odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using random effects models.Results: A total of 20 studies were included. The RRs for all studies was 0.65 (95% CI: 0.57-0.73), with I² = 75.3% and P = 0. In the subgroup analysis, the following variables showed marked heterogeneity: Asian (RR: 0.64; 95% CI: 0.56-0.73) and non-Asian countries (RR: 0.74; 95% CI: 0.45-1.03), female (RR: 0.55; 95% CI: 0.39-0.71) and male + female (RR: 0.64; 95% CI: 0.54-0.75), case-control study (RR: 0.62; 95% CI: 0.52-0.71), impact factor >3 (RR: 0.65; 95% CI: 0.56-0.75), impact factor <3 (RR: 0.64; 95% CI: 0.48-0.80), Newcastle-Ottawa Scale >7 (RR: 0.82; 95% CI: 0.66-0.97) and Newcastle-Ottawa Scale ≤7 (RR: 0.59; 95% CI: 0.49-0.68).Conclusion: Green tea consumption could be a protective factor for esophageal cancer.

Antioxidative and Antimelanoma Effects of Various Tea Extracts via a Green Extraction Method

Tea (Camellia sinensis) contains high level of antioxidant elements and is a well-known beverage consumed worldwide. The purpose of this study is to compare different concentrations of green tea, black tea, oolong tea 861, oolong tea 732, and jasmine green tea. These five types of tea extracts were known to have antioxidative properties, reducing power, and metal ion chelating activity. The current study compared these five extracts in terms of their inhibiting effects on human malignant melanoma: A2058 and A375. To determine the cell viability between normal cell and malignant melanoma cells, an MTT assay was applied to evaluate the cytotoxic potential on human melanoma cells, with all tea extracts showing decreased cell viability with increasing tea extract concentrations. Cytotoxicity on HaCat (normal skin cells) showed no effect on the cell viabilities at lower concentrations of the tea extracts. These results suggest the antioxidative effect of five tea extracts that protect against oxidation and melanoma production, with green tea and jasmine green tea showing the lowest cell viability when tested against malignant melanoma cells.

Association of green tea consumption with mortality from all-cause, cardiovascular disease and cancer in a Chinese cohort of 165,000 adult men

Tea is the most ancient and popular beverage in the world, and its beneficial health effects has attracted tremendous attention worldwide. However, the prospective evidence relating green tea consumption to total and cause-specific mortality is still limited and inconclusive. We recruited 164,681 male participants free of pre-existing disease during 1990-1991, with green tea consumption and other covariates assessed by the standardized questionnaire and mortality follow up continued until 2006 (mean 11 years; total person-years: 1,961,791). Cox regression analyses were used to quantify the associations of green tea consumption with all-cause (n = 32,700), CVD (n = 11,839) and cancer (n = 7002) mortality, adjusting simultaneously for potential confounders. At baseline, 18 % reported regular consumption of green tea. Compared with non-green tea drinkers, regular drinkers had significantly lower all-cause mortality, with adjusted hazard ratios (HRs) being 0.94 (95 % CI 0.89, 0.99) for ≤5 g/day, 0.95 (0.91, 0.99) for 5-10 g/day and 0.89 (0.85, 0.93) for >10 g/day. For CVD mortality, the corresponding HRs were 0.93 (0.85, 1.01) 0.91 (0.85, 0.98) and 0.86 (0.79, 0.93), respectively, while for cancer they were 0.86 (0.78, 0.98), 0.92 (0.83, 1.00) and 0.79 (0.71, 0.88), respectively. The patterns of these associations varied by smoking, alcohol drinking and locality. This large prospective study shows that regular green tea consumption is associated with significantly reduced risk of death from all-cause, CVD and cancer among Chinese adults.

Green tea consumption and risk of esophageal cancer: a meta-analysis of published epidemiological studies

We performed a meta-analysis to analyze the association of various levels of green tea consumption with risk of esophageal cancer. We searched MEDLINE, EMBASE, and the Cochrane Library for studies of green tea consumption and esophageal cancer and identified 12 observational studies. For esophageal cancer, the pooled relative risk (RR) was 1.09 [95% confidence interval (CI), 0.76-1.55] for greatest vs. non/least green tea consumption; however, there was significant heterogeneity across studies (P = 0.00, I(2) = 75.5%). Compared with subjects who drank no/least green tea, the pooled RR was 1.14 (95% CI = 0.97-1.35) for moderate drinkers, 0.94 (95% CI = 0.77-1.13) for those who drank little, and 0.97 (95% CI = 0.77-1.22) for all subjects who had ever drunk green tea. Subgroup analysis showed that the RR was 0.46 (95% CI = 0.29-0.73) for female subjects. The results of the present meta-analysis are that any association between green tea and risk of esophageal cancer remains unclear. Subgroup analyses indicated that greater consumption of green tea might reduce the risk of esophageal cancer in female subjects. However, the results are based on limited research. Further research is needed to confirm the results and clarify the likely biological mechanisms.

Genetic variants in fas signaling pathway genes and risk of gastric cancer

Populations in north central China are at high risk for gastric cancers (GC), and altered FAS-mediated cell signaling and/or apoptosis may contribute to this risk. We examined the association of 554 single nucleotide polymorphisms (SNPs) in 53 Fas signaling-related genes using a pathway-based approach in 1758 GC cases (1126 gastric cardia adenocarcinomas (GCA) and 632 gastric noncardia adenocarcinomas (GNCA)), and 2111 controls from a genome-wide association study (GWAS) of GC in ethnic Chinese. SNP associations with risk of overall GC, GCA and GNCA were evaluated using unconditional logistic regressions controlling for age, sex and study. Gene- and pathway-based associations were tested using the adaptive rank-truncated product (ARTP) method. Statistical significance was evaluated empirically by permutation. Significant pathway-based associations were observed for Fas signaling with risk of overall GC (p = 5.5E-04) and GCA (p = 6.3E-03), but not GNCA (p= 8.1E-02). Among examined genes in the Fas signaling pathway, MAP2K4, FAF1, MAPK8, CASP10, CASP8, CFLAR, MAP2K1, CAP8AP2, PAK2 and IKBKB were associated with risk of GC (nominal p < 0.05), and FAF1 and MAPK8 were significantly associated with risk of both GCA and GNCA (nominal p< 0.05). Our examination of genetic variation in the Fas signaling pathway is consistent with an association of altered Fas signaling and/or apoptosis with risk of GC. As one of the first attempts to investigate a pathway-level association, our results suggest that these genes and the Fas signaling pathway warrant further evaluation in relation to GC risk in other populations.

Tea drinking as a risk factor for neural tube defects in northern China

BACKGROUND

Tea catechins inhibit the activity of the enzyme dihydrofolate reductase, which catalyzes the inactive form of folate 7,8-dihydrofolate to the active form of folate 5,6,7,8-tetrahydrofolate. This inhibition leads to disturbance of the folate metabolic pathway and to lower bioavailability of folate to cells; therefore, it may increase the risk of neural tube defects (NTDs) in a developing embryo. We examined the association between tea drinking during the periconceptional period and the risk of NTDs.

METHODS

Cases were fetuses or neonates with an NTD as ascertained through a population-based surveillance system in 4 rural counties of Shanxi Province in northern China during 2002 through 2007. Controls were term infants without congenital malformations. Demographic, reproductive, and exposure data were obtained through a face-to-face interview.

RESULTS

A total of 631 NTD cases and 857 controls were included in the analysis. Compared with women who did not drink tea during the periconceptional period (487 cases and 688 controls), women who drank tea daily (20 cases and 9 controls) had a 3-fold increased risk (odds ratio = 3.1 [95% confidence interval = 1.4-7.0]) of having an NTD-affected pregnancy. The elevated risk associated with daily tea drinking remained after adjusting for maternal age, educational level, occupation, and periconceptional folic acid supplementation (3.4 [1.4-8.3]). The association was present for all 3 major subtypes of NTDs (ie, anencephaly, spina bifida, and encephalocele).

CONCLUSIONS

Daily tea drinking during the periconceptional period was associated with an elevated risk of NTDs in this Chinese population.

Risk factors for esophageal and gastric cancers in Shanxi Province, China: a case-control study

OBJECTIVE

Smoking and alcohol consumption explain little of the risk for upper-gastrointestinal (UGI) cancer in China, where over half of all cases in the world occur.

METHODS

We evaluated questionnaire-based risk factors for UGI cancers in a case-control study from Shanxi Province, China, including 600 esophageal squamous cell carcinomas (ESCCs), 599 gastric cardia adenocarcinomas (GCAs), 316 gastric noncardia adenocarcinomas (GNCAs), and 1514 age- and gender-matched controls.

RESULTS

Ever smoking and ever use of any alcohol were not associated with risk of UGI cancer; only modest associations were observed between ESCC risk and highest cumulative smoking exposure, as well as GNCA risk and beer drinking. While several associations were noted for socioeconomic and some dietary variables with one or two UGI cancers, the strongest and most consistent relations for all three individual UGI cancers were observed for consumption of scalding hot foods (risk increased 150-219% for daily vs. never users) and fresh vegetables and fruits (risk decreased 48-70% for vegetables and 46-68% for fruits, respectively, for high vs. low quartiles).

CONCLUSION

This study confirms the minor role of tobacco and alcohol in UGI cancers in this region, and highlights thermal damage as a leading etiologic factor.

Genome wide analysis of DNA copy number neutral loss of heterozygosity (CNNLOH) and its relation to gene expression in esophageal squamous cell carcinoma

Background

Genomic instability plays an important role in human cancers. We previously characterized genomic instability in esophageal squamous cell carcinomas (ESCC) in terms of loss of heterozygosity (LOH) and copy number (CN) changes in tumors using the Affymetrix GeneChip Human Mapping 500K array in 30 cases from a high-risk region of China. In the current study we focused on copy number neutral (CN = 2) LOH (CNNLOH) and its relation to gene expression in ESCC.

Results

Overall we found that 70% of all LOH observed was CNNLOH. Ninety percent of ESCCs showed CNNLOH (median frequency in cases = 60%) and this was the most common type of LOH in two-thirds of cases. CNNLOH occurred on all 39 autosomal chromosome arms, with highest frequencies on 19p (100%), 5p (96%), 2p (95%), and 20q (95%). In contrast, LOH with CN loss represented 19% of all LOH, occurred in just half of ESCCs (median frequency in cases = 0%), and was most frequent on 3p (56%), 5q (47%), and 21q (41%). LOH with CN gain was 11% of all LOH, occurred in 93% of ESCCs (median frequency in cases = 13%), and was most common on 20p (82%), 8q (74%), and 3q (42%). To examine the effect of genomic instability on gene expression, we evaluated RNA profiles from 17 pairs of matched normal and tumor samples (a subset of the 30 ESCCs) using Affymetrix U133A 2.0 arrays. In CN neutral regions, expression of 168 genes (containing 1976 SNPs) differed significantly in tumors with LOH versus tumors without LOH, including 101 genes that were up-regulated and 67 that were down-regulated.

Conclusion

Our results indicate that CNNLOH has a profound impact on gene expression in ESCC, which in turn may affect tumor development.

Epidemiological study of risk factors for esophageal cancer in Yangquan Area of Shanxi Province based on discordant sib pairs

AIM: To explore the main environmental risk factors for esophageal squamous cell carcinoma (ESCC) based on discordant sib pairs (DSPs) in a moderately high-incidence area, Yangquan City, Shanxi Province, and to provide theoretical evidence for developing effective control and prevention measures in this area.

METHODS: A 1:1 matched case-control study was carried out. One hundred and twenty-seven DSPs were recruited from the cancer registration and follow-up system of the local hospital. All ESCC cases and their matched unaffected sibs were subjected to a survey to obtain demographic information along with personal and family history, and lifestyle factors. The McNemar test was used for data analysis.

RESULTS: Compared with matched unaffected sibs, low family income (OR = 2.00, 95%CI: 1.14-3.52, P = 0.0143), hot food eating and drinking (OR = 2.56, 95%CI: 1.44-4.57, P = 0.0009) and heavy drinking (P = 0.0027) were risk factors for ESCC in the area. These factors play important roles in the development of ESCC, even in cases with a family history of ESCC, and the odds ratios (95%CI) were 2.18 (1.07-4.45), 5.00(1.91-13.06) and infinity, respectively.

CONCLUSION: Besides genetic factors, lack of nutrition, hot food eating and heavy drinking are main risk factors for ESCC in Yangquan City. Prevention and control of ESCC should be intervened at multiple levels, such as genetic factors and lifestyles.