Inverse association between yoghurt intake and upper aerodigestive tract cancer risk in a Japanese population.

Although the combination of tobacco smoking and alcohol drinking account for approximately 80% of upper aerodigestive tract (UADT) cancer risk, the role of dietary factors, including dairy products, in the risk of these cancers remains controversial. We aimed to evaluate the association between dairy product intake and UADT cancer risk in a Japanese population. We conducted a case-control study in 959 patients with UADT cancer and 2877 sex- and age-matched noncancer control subjects who visited the Aichi Cancer Center in Nagoya, Japan. Data on lifestyle factors, including diet, were obtained by self-administered questionnaire. Associations were assessed by multivariate logistic regression models that considered potential confounders. We found a significant inverse association between yoghurt intake and UADT cancer risk with multivariate-adjusted odds ratios and 95% confidence intervals for <1 time/week, ≥ 1 time/week and <1 time/day, and ≥ 1 time/day consumption of yoghurt of 0.70 (95% confidence interval: 0.54-0.91), 0.67 (0.54-0.84), and 0.73 (0.55-0.95) relative to nonconsumers (P trend=0.005). When stratified by primary tumor site, this association was significant among patients with hypopharyngeal, laryngeal, and esophageal cancer. However, we saw no significant association between milk or butter intake and UADT cancer risk. In this study, we found that a high intake of yoghurt may lower the risk of developing UADT cancer in a Japanese population. Further investigation of this association is warranted.

Causal assessment of smoking and tooth loss: a systematic review of observational studies.

BACKGROUND: Tooth loss impairs oral function. The aim of the present review was to evaluate the causal association between smoking and tooth loss on the basis of high-quality studies. METHODS: Relevant literature was searched and screened, and the methodological quality was assessed. Information on the strength of the association between smoking and tooth loss, the dose-response relationship and natural experimental data was collected and evaluated with respect to consistency and study design. RESULTS: Our literature search yielded 496 citations, and 6 cross-sectional and 2 cohort high-quality studies examining 58,755 subjects in four countries. All studies reported significant associations, although the strength of the association was usually moderate. Four studies reported dose-response relationships between exposure to smoking and the risk of developing tooth loss. A decrease in the risk of tooth loss for former smokers was evident in six studies. Interpretation of evidence for each element was consistent, despite some shortcomings regarding study type and population. CONCLUSIONS: Based on the consistent evidence found with the existing biological plausibility, a causal association between smoking and tooth loss is highly likely. Further studies using a cohort design and different populations are necessary to confirm this association.

Inverse association between toothbrushing and upper aerodigestive tract cancer risk in a Japanese population.

BACKGROUND: Oral hygiene is attracting increasing attention as a potential risk factor for cancers. To investigate the association between toothbrushing frequency and upper aerodigestive tract (UADT) cancer, the authors conducted a large-scale case-control study. METHODS: A total of 856 UADT cancer case participants and 2696 age- and sex-matched control subjects without cancer were included. Edentulous or participants with unknown frequency of toothbrushing or number of remaining teeth were excluded. Associations were assessed by odds ratios and 95% confidence intervals in logistic regression models with adjustment for potential confounders. RESULTS: Compared with toothbrushing once per day, the adjusted odds ratio for brushing twice or more was 0.82 (95% confidence interval: 0.68, 0.99) whereas that for not brushing was 1.79 (0.79, 4.05). This association was observed especially in subjects who had a history of heavy smoking or drinking. CONCLUSIONS: The authors suggest that toothbrushing could have a protective effect for UADT cancer.