Risk factors for lung cancer among Northern Thai women: epidemiological, nutritional, serological, and bacteriological surveys of residents in high- and low-incidence areas

Risk patterns of lung cancer mortality in northern Thailand

Background

Over the past decade, lung cancers have exhibited a disproportionately high mortality and increasing mortality trend in Thailand, especially in the northern region, and prevention strategies have consequently become more important in this region. Spatial analysis studies may be helpful in guiding any strategy put in place to respond to the risk of lung cancer mortality in specific areas. The aim of our study was to identify risk patterns for lung cancer mortality within the northern region of Thailand.

Methods

In the spatial analysis, the relative risk (RR) was used as a measure of the risk of lung cancer mortality in 81 districts of northern Thailand between 2008 and 2017. The RR was estimated according to the Besag-York-Mollié autoregressive spatial model performed using the OpenBUGS routine in the R statistical software package. We presented the overall and gender specific lung cancer mortality risk patterns of the region using the Quantum Geographic Information System.

Results

The overall risk of lung cancer mortality was the highest in the west of northern Thailand, especially in the Hang Dong, Doi Lo, and San Pa Tong districts. For both genders, the risk patterns of lung cancer mortality indicated a high risk in the west of northern Thailand, with females being at a higher risk than males.

Conclusions

There was distinct geographical variation in risk patterns of lung cancer mortality in Thailand. Differences could be related to differences in risk factors such as ground-based radon and air pollution. This study provides a starting point for estimating the spatial pattern of the risk of lung cancer mortality and for examining associations between geographic risk factors and lung mortality for further studies.

Electronic supplementary material

The online version of this article (10.1186/s12889-018-6025-1) contains supplementary material, which is available to authorized users.

Respiratory health issues in the Asia-Pacific region: an overview

The Asia–Pacific region is home to a large heterogeneous population whose respiratory health is influenced by diverse social, economic and environmental factors. Despite this variability, the most prevalent causes of respiratory morbidity and mortality are tobacco smoking, infection, and air pollution. This review aims to summarize current respiratory health issues in the region including smoking‐related diseases especially COPD, lung cancer and infectious problems such as pandemic influenza, the severe acute respiratory syndrome coronavirus, bacterial pneumonia and tuberculosis, as well as the contribution of air pollution to respiratory disease. Published data on trends in the epidemiology and management of respiratory diseases and are summarized; finally, the limitations of available data and projections for the future of respiratory health in the region are discussed.

Effect of combined genetic polymorphisms on lung cancer risk in northern Thai women

Lung cancer is a major cause of cancer-related death in developed countries, and its incidence in developing countries is increasing. In Thailand, cancer incidences differ greatly from region to region, and lung cancer is the most common cancer in the northern Thai population. The polymorphic frequency of 10 genetic susceptibility genes and their association with lung cancer were examined in a northern Thai population: CYP1A1 (MspI), CYP1A1 (Ile462Val), CYP2E1 (PstI), CYP2E1 (DraI), GSTM1, GSTT1, MPO (AciI), OGG1 (Ser326Cys), TP53 (Arg72Pro), and MMP1(AluI). The 173 subjects were 91 lung cancer patients and 82 healthy volunteers. Although no significant association between any single genetic variant and lung cancer risk was observed, when genetic variants were analyzed in combination, a significant effect on lung cancer risk was found for the variant allele in a combination of five genes involved in oxidative stress and inflammatory response: GSTM1 (null), MPO (-463A), OGG1 (326Cys), TP53 (72Pro) (alias p53), MMP1 (2G). With a reference group of individuals carrying at least two wild-type genotypes of these five genes, it was found that an individual carrying three or more variant genotypes is at significantly higher risk of developing lung cancer with the increasing of odds ratios (OR) in concurrence with the number of variant genes. The OR was 2.41 (95% CI = 0.76-7.64), 3.90 (95% CI = 1.23-12.34), and 5.20 (95% CI = 1.31-20.54) for individuals carrying three, four, and five variants, respectively. After stratifying by sex, the OR was higher for women: OR 4.05 (95% CI = 0.44-36.94), 9.00 (95% CI = 0.95-84.89) and 18.00 (95% CI = 1.49-216.62) for three, four, and five variant genotypes, respectively. This augmented effect on lung cancer risk of variant genes involved in oxidative stress and inflammatory response in women with a low prevalence of smoking indicates their modifying effect on other risk factors, such as environmental cigarette smoke, air pollution, radon radiation, or infection of the airway. Confirmation would require further investigations with larger sample sizes.

Worldwide trends in lung cancer pathology

Molecular profiling studies serve to remind us that lung cancer is a complex disease, with different phenotypes that are characterized by variation in morphology as well as molecular composition. Over recent decades, there appear to be worldwide shifts in the relative frequencies of various phenotypic patterns of lung cancer, which are even more striking than changes in the overall incidence of lung cancer. This review summarizes major worldwide trends in lung cancer pathology, which can be explained in part, but not entirely, by changes in cigarette design. Characterizing these trends will be important for recognizing contributions of carcinogens other than tobacco smoke to the worldwide problem of lung cancer.

Lung cancer in Asian women-the environment and genes*

The mortality rate of lung cancer in Asian women has increased significantly in the past few decades. Environmental factors include tobacco smoke (active and environmental), other indoor pollutions (cooking oil vapours, coal burning, fungus spores), diet, and infections. Active tobacco smoking is not the major factor. The relative risk of lung cancer among non-smoking women ever exposed to environmental smoke from their husbands was 1.20 from a meta-analysis. Cooking oil vapours associated with high temperature wok cooking and indoor coal burning for heating and cooking in unvented homes, particularly in rural areas, are risk factors for Chinese women. Chronic benign respiratory diseases due to the fungus Microsporum canis probably accounts for the high incidence of lung cancer in northern Thai women at Sarapee. Diets rich in fruits, leafy green vegetables, and vitamin A are protective, while cured meat (Chinese sausage, pressed duck and cured pork), deep-fried cooking, and chili increased the risk. Tuberculosis is associated with lung cancer. Also, a Taiwanese study showed that the odds ratio of papillomavirus (HPV) 16/18 infection in non-smoking female lung cancer patients was 10.1, strongly suggesting a causative role. Genetic factors have also been studied in Chinese women, including human leucocyte antigens, K-ras oncogene activation, p53 mutation, polymorphisms of phase I activating enzymes (cytochrome P450, N-acetyltransferase slow acetylator status), and phase II detoxifying enzymes (glutathione-S-transferases, N-acetyltransferase rapid acetylator status). New molecular screening technology would facilitate identification of molecular targets for future studies. The interaction between environmental and genetic factors should also be further elucidated.

Carcinogenic potential of tobacco tar-resistant Staphylococcus aureus in buccal cavity

PURPOSE

The effects of cigarette smoking on the association between inflammation and cancer were studied, since some bacteria induce the production of tumor necrosis factor-alpha (TNF-alpha), a proinflammatory cytokine and endogenous tumor promoter, in cells.

METHODS

Bacteria from a gargled solution from the buccal cavity of 20 individuals were cultured in the presence of 4 mg/ml cigarette-smoke condensates. Although cigarette-smoke condensates inhibited growth of Staphylococcus aureus strongly and that of Staphylococcus warneri weakly, tobacco tar-resistant S. aureus and S. warneri were obtained.

RESULTS

One tobacco tar-resistant S. aureus strain (Sa-TA10) induced expression of the TNF-alpha gene in both Bhas 42 cells (v-Ha-ras transfected BALB/3T3 cells) and human lung cancer cell line H226B, while one tobacco tar-resistant S. warneri (Sw-TA75) did not induce it significantly. Moreover, Sa-TA10 induced formation of transformed foci and soft-agar colony in Bhas 42 cells in cooperation with the v-Ha-ras gene. The results suggested that Sa-TA10 has carcinogenic potential, whereas Sw-TA75 does not.

CONCLUSION

These data suggest that tobacco tar-resistant S. aureus, with carcinogenic potential, is present in the buccal cavity of some individuals, and that cigarette smoking simultaneously inhibits growth of most of the bacteria and selects carcinogenic bacteria.

Involvement of TNF-alpha changes in human cancer development, prevention and palliative care

Cancer development and ageing are complex sciences. From the study on the process of rodent carcinogenesis, we identified tumor necrosis factor-alpha (TNF-alpha) as an important mediator of cancer development. This paper presents three clinical examples of TNF-alpha up-regulation: by cord factors of Mycobacterium tuberculosis, such as trehalose 6-monomycolate, as an activator of protein kinase C and by a cord factor like fraction of Microsporum canis obtained in the air inside houses in Thailand, both of which are risk factors in human lung cancer development, and by Helicobacter pylori gene product, H. pylori membrane protein 1 (HP-MP1) in relation to human stomach cancer. The second part of this paper deals with down-regulation of TNF-alpha by a wide variety of cancer preventive agents. Among the various agents, (-)-epigallocatechin gallate (EGCG) and green tea polyphenols inhibited TNF-alpha gene expression in the cells induced by tumor promoter, mediated through inhibition of NF-kappaB activation. Studying growth inhibition of human cancer cell lines by morphine, we found that morphine and the new morphine derivatives KT-90 and KT-87 have anticancer activity mediated through induction of apoptosis, in addition to analgesic action. We conclude that environmental and endogenous factors induce NF-kappaB activation mediated through expression of inflammatory cytokine genes, such as TNF-alpha, and that the expression pattern of the genes operates similarly in the aging process.