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Background: Smokers with low body mass index (BMI) may be more susceptible to lung cancer., Methods: We prospectively examined the association between baseline BMI and lung cancer risk in the Singapore Chinese Health Study, a cohort of 63 257 Chinese enrolled between 1993 and 1998., Results: After adjustment for smoking intensity and duration, BMI was inversely associated with risk of lung cancer among current smokers (P for trend=0.0004). Current smokers at different dosage of smoking with low BMI had significantly higher risk for lung cancer than those with high BMI. Hazard ratios (95% confidence intervals) of lung cancer for heavy smokers with BMI of > or =28, 24-<28, 20-<24, and <20 kg m(-2) were 6.37 (2.10-19.30), 9.01 (5.04-16.10), 8.53 (6.35-11.5), and 11.12 (6.60-18.70), respectively, as compared with nonsmokers. BMI had no modifying effects on lung cancer risk among nonsmokers and former smokers., Conclusion: Smokers with lower BMI may experience an enhanced risk of lung cancer. The findings have significant public-health implication given the increase in smoking prevalence in developing countries, where people still have relatively low BMI.

Objectives: We examined the association among cigarette smoking, smoking cessation and a broad range of cancer incidence and all cause and cause-specific mortality in a population-based cohort of adults of Chinese ethnicity in Singapore., Methods: Subjects were 61,320 participants of the Singapore Chinese Health Study (44.5% men, aged 45-74 years, recruitment from 1993-1998) who were free of cancer at the baseline examination. Main outcomes-of-interest included cancer incidence, all cause and cause-specific mortality as of December 31, 2005., Results: Cigarette smoking was positively associated with overall cancer incidence, including cancers at the following specific sites: head and neck region, upper gastrointestinal tract, hepatobiliary and pancreas cancer, lung, and bladder/renal pelvis cancer. Compared to never smokers, the relative risk (RR) (95% confidence interval [CI]) of cancer incidence (all cancer sites) among current smokers smoking >22 cigarettes/day was 1.9 (1.7-2.1), p-trend<0.0001. Similarly, cigarette smoking was associated with all cause and cause-specific mortality, including deaths due to cancer, ischemic heart disease, other heart diseases, and chronic obstructive pulmonary disease. Compared to never smokers, RR (95%CI) of all cause mortality among current smokers smoking >22 cigarettes/day was 1.8 (1.6-2.0), p-trend<0.0001. Also, relative to current smokers, ex-smokers experienced reduced cancer incidence and total mortality. The population attributable risk of smoking in men for cancer incidence as well as all-cause mortality was 23%, whereas in women it ranged from 4-5%., Conclusions: Cigarette smoking is an important risk factor for cancer incidence and major causes of mortality in Chinese men and women of Singapore.

Although studies in Western populations have shown that smokers have decreased dietary intakes of antioxidants and other health-related nutrients, this has not been established in oriental populations. This study aimed to identify differences in dietary and lifestyle characteristics between current, former, and never-smokers among middle-aged and older Chinese in Singapore. The subjects, 45-74 y old, were participants in the Singapore Chinese Health Study, a prospective cohort that enrolled 63,257 (27,959 men and 35,298 women) Chinese in Singapore between 1993 and 1998. Data on current dietary habits (using a validated, semiquantitative FFQ) and other lifestyle factors were collected through face-to-face interviews. Mean daily intakes of various nutrients were estimated using a food composition table that was specifically developed for this population. The current smoking rates were 36% in men and 6% in women; an additional 22% of men and 3% of women were former smokers. In both sexes, current smokers were less educated, had lower BMI, led a more sedentary lifestyle, and drank more alcohol and coffee than those who never smoked. Current smokers had dose-dependent decreases in the intakes of a wide range of antioxidants, vitamins, fiber, and calcium, but increases in the intakes of cholesterol and nitrosamines compared with people who never smoked. Former smokers had dietary intakes that either were similar to never-smokers or intermediate between current and never-smokers. Our results are consistent with findings among Western populations, and suggest that the unhealthy diet and lifestyle in smokers occur across diverse cultures.

Alcohol and tobacco consumption are closely correlated and published results on their association with breast cancer have not always allowed adequately for confounding between these exposures. Over 80% of the relevant information worldwide on alcohol and tobacco consumption and breast cancer were collated, checked and analysed centrally. Analyses included 58,515 women with invasive breast cancer and 95,067 controls from 53 studies. Relative risks of breast cancer were estimated, after stratifying by study, age, parity and, where appropriate, women's age when their first child was born and consumption of alcohol and tobacco. The average consumption of alcohol reported by controls from developed countries was 6.0 g per day, i.e. about half a unit/drink of alcohol per day, and was greater in ever-smokers than never-smokers, (8.4 g per day and 5.0 g per day, respectively). Compared with women who reported drinking no alcohol, the relative risk of breast cancer was 1.32 (1.19-1.45, P<0.00001) for an intake of 35-44 g per day alcohol, and 1.46 (1.33-1.61, P<0.00001) for >/=45 g per day alcohol. The relative risk of breast cancer increased by 7.1% (95% CI 5.5-8.7%; P<0.00001) for each additional 10 g per day intake of alcohol, i.e. for each extra unit or drink of alcohol consumed on a daily basis. This increase was the same in ever-smokers and never-smokers (7.1% per 10 g per day, P<0.00001, in each group). By contrast, the relationship between smoking and breast cancer was substantially confounded by the effect of alcohol. When analyses were restricted to 22 255 women with breast cancer and 40 832 controls who reported drinking no alcohol, smoking was not associated with breast cancer (compared to never-smokers, relative risk for ever-smokers=1.03, 95% CI 0.98-1.07, and for current smokers=0.99, 0.92-1.05). The results for alcohol and for tobacco did not vary substantially across studies, study designs, or according to 15 personal characteristics of the women; nor were the findings materially confounded by any of these factors. If the observed relationship for alcohol is causal, these results suggest that about 4% of the breast cancers in developed countries are attributable to alcohol. In developing countries, where alcohol consumption among controls averaged only 0.4 g per day, alcohol would have a negligible effect on the incidence of breast cancer. In conclusion, smoking has little or no independent effect on the risk of developing breast cancer; the effect of alcohol on breast cancer needs to be interpreted in the context of its beneficial effects, in moderation, on cardiovascular disease and its harmful effects on cirrhosis and cancers of the mouth, larynx, oesophagus and liver.

The factors associated with risk of lung cancer among nonsmokers have not been fully elucidated, but dietary factors have consistently been shown to play a role. Chinese women are unique in having a high incidence of lung cancer despite a low smoking prevalence. This population is also known to have a high intake of soy, a dietary source of phytoestrogens. We conducted a hospital-based case-control study among Singapore Chinese women, comprising 303 cases and 765 age-matched controls, of whom 176 cases and 663 controls were lifetime nonsmokers. Data on demographic background, reproductive factors and dietary intake of fruit, vegetables and soy foods were obtained by in-person interview. We observed an inverse association between intake of total, cruciferous and non-cruciferous vegetables and risk of lung cancer among smokers. Although smokers in the highest tertile of fruit intake also had a lower risk, this was not statistically significant. Higher intake of soy foods significantly reduced risk of lung cancer among lifetime nonsmokers, but not among smokers. When soy isoflavonoid intake in mg/week was computed based on frequency and portion size of intake of eight common local soy foods, the adjusted OR among nonsmokers for the highest tertile compared to the lowest was 0.56, 95% CI 0.37-0.85 (p for trend <0.01). Fruit intake was also significantly associated with reduced lung cancer risk among nonsmokers, but the effect was not significant after adjustment for soy intake. On the other hand, soy intake remained an independent predictor of risk after controlling for fruit intake. Reproductive effects were also primarily confined to lifetime nonsmokers, among whom having 3 or more livebirths (adjusted OR 0.65, 0.44-0.96) and a menstrual cycle length of more than 30 days (OR 0.46, 0.25-0.84) accorded a significantly reduced risk of lung cancer. Place of birth was significantly associated with risk among nonsmokers (OR 2.6, 1.7-3.9 for China-born vs. local born) but not among smokers. When analysis was restricted to nonsmokers with adenocarcinomas, the dietary effects were consistent or enhanced. On stepwise regression, soy intake and cycle length emerged as the independent dietary and reproductive predictors of lung cancer risk in nonsmokers. These findings are consistent with other evidence suggesting an involvement of estrogen-related pathways in lung cancer among non-smoking women., (Copyright 2001 Wiley-Liss, Inc.)

Smoking is well established as a main cause of preventable mortality throughout the world, but little data are available on Asian populations and none on Singapore. This study is the first to provide data specific to Singapore on the increased mortality among smokers, and is one of the few such studies on Asians. In 1974, smoking history data were taken from a random sample of 3579 adults living in Singapore. Of these, 3361 (1522 men and 1839 women) were eligible for follow-up and vital status was determined as at 31 December 1993. Cox regression analysis was used to estimate the relative risks of variety of causes of death for smokers compared to non-smokers, adjusted for age and ethnicity. Smoking was categorized as ever or never and also as none, light or heavy. As at 31 December 1993, 330 (21.7%) of the men and 249 (13.5%) of the women had died. Relative risk values were clearly elevated for male and female smokers for all-cause mortality (1.42 and 1.52, respectively), lung cancer (13.2, 6.37) and death due to chronic obstructive pulmonary disease (COPD) (4.71, 8.50). Relative risk values for death from cancer of the larynx or oesophagus, ischaemic heart disease and cerebrovascular disease were elevated but not significantly different from 1.0. A trend of increasing risk with increasing smoking intensity was seen for all-cause mortality among men and for lung cancer and COPD mortality, among both sexes. Ethnicity was associated with ischaemic heart disease mortality among men, with elevated risks in both the Indians (2.55) and the Malays (1.66) relative to the Chinese. These results should serve to strengthen the anti-smoking campaigns in Singapore.

Benzene exposure causes leukemia and lymphomas. Recent epidemiological findings have also shown an association between cigarette smoking and an increased risk of leukemia. However, further evidence is required to document the biological plausibility of this association. In evaluating this link, it is important to note that cigarette smoke contains benzene and various pyrolytic compounds, among other carcinogens. This study aims to determine the uptake of benzene by measuring 3 benzene-related compounds in cigarette smokers and non-smokers. Urinary concentrations of catechol (CAT), hydroquinone (HQ), and trans,trans-muconic acid (tt-MA) were measured by high-performance liquid chromatography (HPLC) with fluorimetric and UV detection, respectively. The results showed that these compounds were present in all urine samples. However, the concentrations were significantly higher in smokers than in non-smokers. The mean level of urinary tt-MA was 0.19 +/- 0.09 mg/g creatinine for 46 male smokers and the corresponding value for 40 non-smokers was 0.14 +/- 0.07 mg/g creatinine. The mean concentrations of HQ and CAT were 0.81 +/- 0.4 and 3.51 +/- 2.6 mg/g creatinine for smokers, and 0.45 +/- 0.4 and 1.94 +/- 1.2 mg/g creatinine for non-smokers, respectively. These results suggest that cigarette smoking is associated with a significant additional exposure to benzene and its related compounds. Furthermore, significant correlations were observed between the concentrations of cotinine, the metabolite of nicotine, and the above compounds. These findings suggest that the exposure originated from cigarette smoking.

In a nationwide survey of blood pressures in Singapore, the prevalence of current smoking was estimated at about 27% for all persons aged 20 years and above. There is male predominance of 5:1, with the peak age among them at 40-49 years. The majority are cigarette smokers; with mean daily consumption at 16.1 for males and 10.7 for females. The study has shown no significant differences in mean systolic and diastolic blood pressures between cigarette smokers and non-smokers at every age-group from 20 to 69 years. There is also no higher prevalence of hypertension among smokers. These findings confirm various other epidemiological studies, especially those in the West where smoking is at a much higher level. Smoking as a risk factor in ischaemic heart distance cannot, therefore, be attributed to its long-term effects on the blood pressure. It is also not likely to be a cause of essential hypertension.

In the mid-seventies, a few base-line survey showed an average of about 25% of adults (aged 15 years and above) were regular smokers. Males predominated (6-8:1), prevalence increased with age reaching peak after 40 years and cigarette consumption was 16/day in males and 10/day in females. Malays tended to have higher smoking rates, so were those with little or no education. In 1984, a repeat survey showed the overall rate at 19% and the age-specific rates had declined, especially in the group above 40 years (by up to 30%). Again, in 1987, another survey showed the overall rate at 13.6% and age-specific rates declined by another 30% from 1984. With the National Smoking Control Programme at full steam, there is every prospect that we will be able to achieve our goal of becoming a nation of non-smokers.