Tooth Loss and Risk of Lung Cancer among Urban Chinese Adults: A Cohort Study with Meta-Analysis.

Epidemiological evidence on tooth loss and lung cancer risk remains limited, especially for smoking-specific associations. To investigate the association between tooth loss and lung cancer risk by smoking status, we first analyzed data from the Shanghai Men's Health Study (n = 49,868) and the Shanghai Women's Health Study (n = 44,309). Cox regression models were applied to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) for lung cancer risk in relation to tooth loss. We also conducted a meta-analysis to summarize epidemiologic findings to date, incorporating results from the current study and six previously published studies. For 7.3 median follow-up years, 973 incident lung cancer cases (613 men and 360 women) were ascertained. After adjustment for major covariates, tooth loss was associated with an increased risk of lung cancer among men (HR [95% CI] for >10 teeth vs. none = 1.59 [1.21−2.11]) but not among women (0.86 [0.50−1.46]). The positive association was stronger among male current smokers (1.75 [1.26−2.45], p-interaction by smoking status = 0.04). In a meta-analysis incorporating 4052 lung cancer cases and 248,126 non-cases, tooth loss was associated with a 1.64-fold increased risk of developing lung cancer (relative risk [RR, 95% CI] for the uppermost with the lowest category = 1.64 [1.44−1.86]). The positive association was more evident among current smokers (1.86 [1.41−2.46]), but no significant associations were found among never or former smokers. Our findings suggest that tooth loss may be associated with an increased risk of lung cancer, and the association could be modified by smoking status.

[Feasibility of genetic polymorphisms analysis using genomic DNA obtained from human buccal cells].

BACKGROUND & OBJECTIVE: Using DNA samples obtained from buccal cells for genetic polymorphism analysis in molecular epidemiological studies has been repeatedly reported, but whether DNA from food remnants in mouth influences the result is still concerned. This study was to compare genetic polymorphisms of buccal cell DNA with those of buffy coat DNA, and with plant and animal DNA from foods to rule out the possibility of interference from food remnants, to improve technique of buccal cell collection and elevate DNA yield. METHODS: Buccal cells were collected from mouthwash (40 ml/case) of 62 subjects, and fixed with isopropyl alcohol; buffy coats of peripheral blood were collected from 30 of these subjects. Common foods (rice, greengrocery, soybean, apple, pork, beef, chicken, and duck) were also collected. DNA of all samples was extracted by chloroform-phenol method. NAT2, GSTM1, GSTT1, CYP1A1, and CYP2E1 genetic polymorphisms were assayed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. Alu (human mutual DNA sequence) was also tested. RESULTS: DNA yield of 62 individual mouthwash samples was (135.15+/-64.30) microg (22.36-330.70 microg); 30 individual mouthwash samples contained 75%-95% oral epithelial cells with DNA yield of (143.44+/-61.64) microg (51.01-283.58 microg). DNA yield of 30 buffy coat samples was (91.19+/-38.01) microg (30.83-178.63 microg). Electrophoresis showed that all 62 buccal cell samples and 30 buffy coat samples contained DNA fragments in high molecular weight; beta-globin, Alu, NAT2, GSTM1, GSTT1, CYP1A1, and CYP2E1 gene fragments were successfully amplified from 61 buccal cells samples and 30 buffy coat samples, which showed no difference between the 2 kinds of samples from individual collections; these gene fragments were not amplified from all food DNA samples. CONCLUSIONS: The majority of DNA from mouthwash is human-origin. A little amount of food remnants would not influence the measurements of genetic polymorphisms. The genetic polymorphisms show no difference between buccal cell samples and buffy coat samples.

Urinary tea polyphenols in relation to gastric and esophageal cancers: a prospective study of men in Shanghai, China.

Experimental studies have shown that tea and tea polyphenols have anticarcinogenic properties. There have been no prospective investigations examining the relationship between tea polyphenols and cancer risk using validated biomarkers. In the present study, a nested case-control study design was used to investigate the association between prediagnostic urinary tea polyphenol markers and subsequent risk of gastric and esophageal cancers. One hundred and ninety incident cases of gastric cancer and 42 cases of esophageal cancer occurring in members of the Shanghai Cohort (18 244 men aged 45-64 years at recruitment with up to 12 years of follow-up) were compared with 772 cohort control subjects. The control subjects were individually matched to the index cases by age, month and year of sample collection, and neighborhood of residence (case-control ratio = 1:3 for gastric cancer, 1:5 for esophageal cancer). Urinary tea polyphenols, including epigallocatechin (EGC) and epicatechin (EC), and their respective metabolites 5-(3',4',5'-trihydroxyphenyl)-gamma-valerolactone (M4) and 5-(3',4'-dihydroxyphenyl)-gamma-valerolactone (M6), were measured in all study subjects by means of a validated assay. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated from logistic regression models. After exclusion of cases diagnosed under 4 years follow-up, urinary EGC positivity showed a statistically significant inverse association with gastric cancer (OR = 0.52, 95% CI = 0.28-0.97) after adjustment for Helicobactor pylori seropositivity, smoking, alcohol drinking, and level of serum carotenes. The protective effect was primarily seen among subjects with low (below population median) serum carotenes. The odds ratio for EGC positivity was 0.49 (95% CI = 0.26-0.94) among subjects with low serum carotenes while the corresponding odds ratio among subjects with higher levels of serum carotenes was 1.02 (95% CI = 0.46-2.28). Similar tea polyphenol-cancer risk associations were observed when the gastric cancer and esophageal cancer sites were combined. The present study provides direct evidence that tea polyphenols may act as chemopreventive agents against gastric and esophageal cancer development.