Smoking cessation and lung cancer risk in an Asian population: findings from the Singapore Chinese Health Study.

BACKGROUND: Smoking cessation is an important strategy for reducing the harmful effects of tobacco, particularly in the prevention of lung cancer; however, prospective data on the impact of smoking cessation on lung cancer risk in Asian populations are limited. METHODS: We studied a population-based cohort of Chinese men and women aged 45-74 years--participants of the Singapore Chinese Health Study. Information on smoking, lifestyle and dietary habits was collected at the time of recruitment in 1993-1998; and smoking status was assessed again at a second interview in 1999-2004 (mean interval 5.8 years). Participants were followed up to 31 December 2007, and incident cases of lung cancer were ascertained by linkage with population-wide registries. RESULTS: Among 45,900 participants, there were 463 incident cases of lung cancer. Relative to current smokers, those who quit smoking subsequent to baseline assessment had a 28% decrease in the risk of lung cancer (adjusted hazard ratio (HR) 0.72; 95% CI (95% confidence interval): 0.53-0.98). The risk was less than half in ex-smokers who had quit before the first interview and maintained their status (HR 0.42; 95% CI: 0.32-0.56). CONCLUSIONS: Reduction in lung cancer incidence with smoking cessation in Asian populations is substantial and can be observed within a few years after quitting.

Global health: challenges and opportunities for Singapore.

Over the past decade, global health has evolved from a buzzword to a discipline, attracting interest from governments, academic institutions and funding organisations. Global health centres, institutes and initiatives in Western countries have increased in both size and number, aided primarily by institutional backing and supportive funding mechanisms. As the rise to prominence of global health on the public health agenda also coincides with shifts in global balances of power, Asia, as well as Singapore, has an expanded role to play in supporting global health teaching and research, both in the region and throughout the world. Foundations, universities, government agencies, statutory boards and the private sector all have an important role to play in moving the global health agenda forward in Singapore. Rigorous global health training and increased funding for global health research are now timely and essential in order for global health, as a discipline, to develop within Singapore and have an impact within the region.

Meta- and pooled analysis of GSTT1 and lung cancer: a HuGE-GSEC review.

Lung cancer is the most common malignancy in the Western world, and the main risk factor is tobacco smoking. Polymorphisms in metabolic genes may modulate the risk associated with environmental factors. The glutathione S-transferase theta 1 gene (GSTT1) is a particularly attractive candidate for lung cancer susceptibility because of its involvement in the metabolism of polycyclic aromatic hydrocarbons found in tobacco smoke and of other chemicals, pesticides, and industrial solvents. The frequency of the GSTT1 null genotype is lower among Caucasians (10-20%) than among Asians (50-60%). The authors present a meta- and a pooled analysis of case-control, genotype-based studies that examined the association between GSTT1 and lung cancer (34 studies, 7,629 cases and 10,087 controls for the meta-analysis; 34 studies, 7,044 cases and 10,000 controls for the pooled analysis). No association was observed between GSTT1 deletion and lung cancer for Caucasians (odds ratio (OR) = 0.99, 95% confidence interval (CI): 0.87, 1.12); for Asians, a positive association was found (OR = 1.28, 95% CI: 1.10, 1.49). In the pooled analysis, the odds ratios were not significant for either Asians (OR = 0.97, 95% CI: 0.83, 1.13) or Caucasians (OR = 1.09, 95% CI: 0.99, 1.21). No significant interaction was observed between GSTT1 and smoking on lung cancer, whereas GSTT1 appeared to modulate occupational-related lung cancer.

The reliability, validity and sensitivity to change of the Chinese version of SF-36 in oriental patients with rheumatoid arthritis.

OBJECTIVE: To assess the reliability, validity and sensitivity to change of a Chinese version of the 36-item Short-Form Health Survey (SF-36) in Chinese-speaking patients with rheumatoid arthritis (RA) in Singapore. METHODS: The psychometric properties of the Chinese Hong Kong standard version of the SF-36 were assessed in 401 RA patients. The construct validity of the Chinese SF-36 was assessed by comparison with the American College of Rheumatology (ACR) functional status, a validated Chinese Health Assessment Questionnaire (C-HAQ) and markers of RA activity and severity. RESULTS: The overall Cronbach's coefficient alpha was 0.921, reflecting excellent internal consistency. The instrument showed reasonable test-retest reliability except in the social functioning (SF) subscale. There was a significant ceiling effect in the role physical (RP), SF and role emotional (RE) subscales and a floor effect in the RP and RE subscales. Physical function (PF) and SF were strongly correlated with C-HAQ and patient's assessment of RA activity [Pearson's correlation coefficient (r) ranging from -0.41 to -0.53] and moderately correlated with ACR functional status (r = -0.35 and -0.3, respectively). Weak correlations were also found between the Chinese SF-36 and markers of RA activity, deformed joint count and radiographic damage. PF and SF were the subscales most responsive to change in quality of life (QOL). CONCLUSION: The Chinese SF-36 showed reasonable reliability, criterion validity and responsiveness with limitations in certain subscales. Overall, the physical domains and PF in particular may be the most ideal psychometric measures of QOL in RA.

Heterocyclic aromatic amines in domestically prepared chicken and fish from Singapore Chinese households.

Chicken and fish samples prepared by 42 Singapore Chinese in their homes were obtained. Researchers were present to collect data on raw sample weight, cooking time, maximum cooking surface temperature, and cooked sample weight. Each participant prepared one pan-fried fish sample and two pan-fried chicken samples, one marinated, one not marinated. The cooked samples were analyzed for five heterocyclic aromatic amine (HAA) mutagens, including MeIQx (2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline); 4,8-DiMeIQx (2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline); 7,8-DiMeIQx (2-amino-3,7,8-trimethylimidazo[4,5-f]quinoxaline); PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine), and IFP (2-amino-(1,6-dimethylfuro[3,2-e]imidazo[4,5-b])pyridine). A paired Student's t-test showed that marinated chicken had lower concentrations of PhIP (p<0.05), but higher concentrations of MeIQx (p<0.05) and 4,8-DiMeIQx (p<0.001) than non-marinated chicken, and also that weight loss due to cooking was less in marinated chicken than in non-marinated chicken (p<0.001). Interestingly, the maximum cooking surface temperature was higher for fish than for either marinated or non-marinated chicken (p<0.001), yet fish was lower in 4,8-DiMeIQx per gram than marinated or non-marinated chicken (p<0.001), lower in PhIP than non-marinated chicken (p<0.05), and lost less weight due to cooking than either marinated or non-marinated chicken (p<0.001). Fish was also lower in MeIQx and 7,8-DiMeIQx than marinated chicken (p<0.05). This study provides new information on HAA content in the Singapore Chinese diet.

Second primary cancers among 109 000 cases of non-Hodgkin's lymphoma.

An analysis of other primary cancers in individuals with non-Hodgkin's lymphoma (NHL) can help to elucidate this cancer aetiology. In all, 109 451 first primary NHL were included in a pooled analysis of 13 cancer registries. The observed numbers of second cancers were compared to the expected numbers derived from the age-, sex-, calendar period- and registry-specific incidence rates. We also calculated the standardised incidence ratios for NHL as a second primary after other cancers. There was a 47% (95% confidence interval 43-51%) overall increase in the risk of a primary cancer after NHL. A strongly significant (P<0.001) increase was observed for cancers of the lip, tongue, oropharynx*, stomach, small intestine, colon*, liver, nasal cavity*, lung, soft tissues*, skin melanoma*, nonmelanoma skin*, bladder*, kidney*, thyroid*, Hodgkin's lymphoma*, lymphoid leukaemia* and myeloid leukaemia. Non-Hodgkin's lymphoma as a second primary was increased after cancers marked with an asterisk. Patterns of risk indicate a treatment effect for lung, bladder, stomach, Hodgkin's lymphoma and myeloid leukaemia. Common risk factors may be involved for cancers of the lung, bladder, nasal cavity and for soft tissues, such as pesticides. Bidirectional effects for several cancer sites of potential viral origin argue strongly for a role for immune suppression in NHL.

Potential sources of carcinogenic heterocyclic amines in the Chinese diet: results from a 24-h dietary recall study in Singapore.

OBJECTIVE: Heterocyclic amines (HCAs) from high-temperature cooking of meat have been linked to increased cancer incidence in Western populations, but data on the sources of HCAs in Asian diets are scarce. Our aim was to identify potential sources of HCAs in the Chinese diet, and to provide the basis for efforts to quantify dietary exposure to these compounds. DESIGN AND SETTING: We conducted 24-h dietary recall interviews among 986 Chinese men and women in Singapore, who were a randomly selected subpopulation of participants from the Singapore Chinese Health Study, a population-based cohort. Details of all foods and beverages consumed by each subject in the past 24 h were recorded, and information on meat type, cooking method and portion size were abstracted from all meat-containing dishes, and gram weight equivalents computed. RESULTS: The mean meat intake per person was 103.0 g/day (standard deviation 74.2), of which 97.2% was fresh meat. Fish (38.0%), pork (30.6%), and poultry (21.0%) accounted for 89.6% of meat consumed. Patterns of meat consumption and cooking methods differed markedly from Western populations. Documented high-temperature cooking methods, combined with stir-frying, accounted for 44.3% of fish, 35.1% of pork and 25.6% of poultry consumed. Specifically, potentially significant sources of HCAs were pan-fried fish and barbecued pork. CONCLUSIONS: Our results identify the potential sources of HCA in the Chinese diet, highlight aspects which are relevant to HCA formation and intake, and call for novel approaches to estimating individual exposure to dietary HCAs in this and similar populations.

Trends in cancer incidence among Singapore Malays: a low-risk population.

INTRODUCTION: Inspection of trends in cancer incidence in ethnically or geographically diverse populations is important for the understanding of cancer patterns and also to provide clues for aetiologic studies. There is little information on cancer incidence among Malays, a low-risk population. The population-based cancer registration system in Singapore offers the opportunity in this regard. MATERIALS AND METHODS: A review of all newly diagnosed cancer cases among Singapore Malay residents in the period 1968 to 1997 was conducted to determine the time trends using data from Singapore Cancer Registry. Age-standardised incidence rates and average annual percentage change, using Poisson regression, were calculated. RESULTS: During the 30-year study period, a total of 9101 incident cases of cancer were diagnosed among Malays in Singapore. The 3 most common sites of cancer were lung, liver and colorectum in males; and breast, colorectum and ovary in females in the period 1983 to 1997. Leukaemia was among the top 10 cancer sites in both sexes. Malays generally experienced lower cancer incidence rates compared to Chinese, but rates have been increasing at 1.5% to 2% annually. Statistically significant increases in incidence were observed for most of the cancer sites. The incidence of nasopharyngeal carcinoma increased, while there were no significant changes in the general population. CONCLUSION: The relatively lower cancer risk among Singapore Malays might be attributed to genetic factors or closer adherence to a more traditional lifestyle. This study provides a baseline for comparisons with other populations with diverse cancer risk patterns in order to obtain a better understanding of possible aetiologic factors.

Survival among Chinese women with lung cancer in Singapore: a comparison by stage, histology and smoking status.

Lung cancer generally carries a poor prognosis and the determinants of survival have been of interest. However, survival estimates in Asian populations are scarce. This study describes survival rates and their determinants in Singapore Chinese women, a primarily non-smoking population. Three hundred and twenty-six Chinese women, diagnosed with primary lung carcinoma in three major hospitals in Singapore between April 1996 and December 1998, were followed up till 31 December 2000. The Kaplan-Meier method was used for survival analysis. Two hundred and eighty (85.7%) died from the disease during follow-up. The median survival time was 0.7 years and the three-year survival was 15.8%. These survival rates are similar to those of Western populations, and they provide a basis for examining trends over time. Age at diagnosis was an independent prognostic factor [adjusted hazard ratio (relative risk) 1.4, 95% confidence intervals (CI) 1.1-1.9 for women above 65 years relative to younger women]. Most (70.5%) tumours were stage III/IV at diagnosis. Three-year survival ranged from 72% among patients with stage I tumours to 7% for stage IV tumours. Overall, there was no survival difference among different histological types in all stages combined. When limited to stages I and II cancers, adenocarcinomas were associated with a better outcome relative to other histological subtypes combined (adjusted relative risk 0.4, 95% CI 0.1-1.0). Smoking was an independent risk factor (adjusted relative risk 1.3, 95% CI 1.0-1.8). Nevertheless, non-smokers comprised 57.4% of this series, highlighting the importance of increased awareness among health professionals and the public that lung cancer is not only a disease of smokers. The high proportion of late-stage tumours in this study and the impact of disease stage on outcome underline the importance of early detection in improving survival of lung cancer.

The Internet as a source of health information among Singaporeans: prevalence, patterns of health surfing and impact on health behaviour.

OBJECTIVE: The Internet is an increasingly popular source of healthcare information. This study describes the prevalence of health surfers in Singapore and their health-surfing patterns. It also assesses their confidence in online health information and the impact the Internet has on health-seeking behaviour. MATERIALS AND METHODS: A cross-sectional survey using a standardised questionnaire was carried out among residents aged 13 to 55 years in 1852 units in Bishan North. These units were selected by single-stage simple random cluster sampling method. RESULTS: The household response rate was 51% (n = 950) and the individual response rate was 69% (n = 1646). Responding and non-responding households were similar in terms of ethnicity and housing type. Of the responders, 62.9% surfed the Internet and 37.7% have surfed for health information. Health surfers tended to be younger (20 to 39 years) and have higher education status. Indians were also more likely than other ethnic groups to surf for health. Professional health-related sites comprised the majority (68%) of sites visited, and the most common search keywords concern chronic degenerative diseases, e.g. hypertension. The top preferred sources of health information were doctors (25.9%), the Internet (25.3%) and the traditional mass media (20.5%). Almost half (45.1%) considered online health information trustworthy if it was from a professional source or if the website displayed the source, while 10.6% trusted the information if it concurred with the doctors' advice. The vast majority (91.7%) had taken some action in response to the information. CONCLUSION: The Internet is being used as an accessible source of health information by a substantial proportion of the lay public. While this can facilitate greater partnership in healthcare, it underlines the need for doctors to be pro-active in the practice of evidence-based medicine, and for guidelines to enable patients to use this tool in a discerning manner.

Dietary isothiocyanates, glutathione S-transferase -M1, -T1 polymorphisms and lung cancer risk among Chinese women in Singapore.

Chinese populations consume a diet relatively high in isothiocyanates (ITCs), a derivative of cruciferous vegetables known to have cancer-protective effects. This class of compounds is metabolized by the glutathione S-transferase family of enzymes, which are also involved in the detoxification of tobacco-related carcinogens such as polycyclic aromatic hydrocarbons and alkyl halides. We evaluated the association between dietary isothiocyanate intake, GSTM1 and GSTT1 polymorphisms, and lung cancer risk in 420 Chinese women: 233 histologically confirmed lung cancer patients and 187 hospital controls. Among these, 58.8% of cases and 90.3% of controls were lifetime nonsmokers. An allele-specific PCR method was used to detect the presence or absence of the GSTM1 and GSTT1 genes in DNA isolated from peripheral blood. Higher weekly intake of ITCs (above the control median value of 53.0 micromol) reduced the risk of lung cancer to a greater extent in smokers [adjusted odds ratio (OR), 0.31; 95% confidence interval (CI), 0.10-0.98] than nonsmokers (OR, 0.70; 95% CI, 0.45-1.11). The inverse association was stronger among subjects with homozygous deletion of GSTM1 and/or GSTT1. Among nonsmokers with GSTM1-null genotype, higher intake of ITCs significantly reduced the risk of lung cancer (OR, 0.54; 95% CI, 0.30-0.95), an effect not seen among those with detectable GSTM1 (OR, 1.07; 95% CI, 0.50-2.29). Our results, in a Chinese female population, are consistent with the hypothesis that ITC is inversely related to the risk of lung cancer, and we show that among nonsmokers this effect may be primarily confined to GST-null individuals. Conjugation and elimination of ITCs is enhanced in GST-non-null relative to -null individuals, such that the GST metabolic genotype modifies the protective effect of ITCs on lung cancer development.

Population-based cancer survival in Singapore, 1968 to 1992: an overview.

The Singapore Cancer Registry has provided comprehensive population-based incidence data since 1968. This paper describes the population-based survival analysis of the registry data. All invasive primary cancers diagnosed from January 1, 1968 to December 31, 1992 were passively followed up until December 31, 1997. Only 5.8% were lost to follow-up. Cumulative and observed survival rates were calculated using Hakulinen's method. Overall 5-year relative survival rates have increased dramatically over the 25-year period in both genders. Significant increases are seen with nasopharynx, stomach and colo-rectum cancers, non-Hodgkin's lymphoma, leukemias and cancers of the testis, cervix, ovaries and breast. When compared with the Surveillance, Epidemiology and End Results (SEER) rates in the United States, the 5-year relative survival rates in Singapore are generally lower. However, the rate of change between the two countries is fairly similar. On the average, the rates are 10 to 15 years behind the SEER rates and 5 to 10 years behind Finland, Switzerland and Japan, but they are close to the UK rates. The age-standardized 5-year survival rate for Singapore is higher for most sites compared with other developing countries like Qidong (China), Madras (India), Bombay (India) and Chiang Mai (Thailand). The 25-year trend in cancer survival in Singapore showed two extreme groups: those showing no change and those showing significant improvements. Reducing the incidence of cancers belonging to the first group remains the only viable mode of cancer control. For cancers in the second group, improvement in survival is due to a combination of successful early detection measures and effective treatment services in Singapore.

Do urinary estrogen metabolites reflect the differences in breast cancer risk between Singapore Chinese and United States African-American and white women?

Breast cancer risk is substantially lower in Singapore than in women from the United STATES: Part of the risk discrepancy is probably explained by differences in the production of endogenous estrogens, but differences in the pathway by which estrogen is metabolized may also play a role. We undertook a study to determine whether the ratio of urinary 2-hydroxyestrone (2OHE(1)):16alpha-hydroxyestrone (16alpha-OHE(1)) was higher in Singapore Chinese than in a group of United States (predominantly African-American) women living in Los ANGELES: We also wanted to determine whether any difference in estrogen metabolite ratio between these two groups of women was greater than that in estrone (E(1)), estradiol (E(2)) and estriol (E(3)). The participants in this study were randomly selected healthy, non-estrogen using women participating in the Singapore Chinese Health Study (n = 67) or the Hawaii/Los Angeles Multiethnic Cohort Study (n = 58). After adjusting for age and age at menopause, mean urinary 2-OHE(1) was only 23% (P = 0.03) higher in Singapore Chinese than in United States women, and there were no statistically significant differences in 16alpha-OHE(1) levels or in the ratio of 2-OHE(1):16alpha-OHE(1) between the two groups. The adjusted mean 2-OHE(1):16alpha-OHE(1) ratio was 1.63 in Singapore Chinese and 1.48 in United States women (P = 0.41). In contrast, the adjusted mean values of E1, E2, and E3 were 162% (P < 0.0001), 152% (P < 0.0001), and 92% (P = 0.0009) higher, respectively, in United States women than in Singapore Chinese women. Our study suggests that urinary E1, E2, and E3 reflect the differences in breast cancer risk between Singapore Chinese and United States women to a stronger degree than the estrogen metabolites 2OHE(1) and 16alpha-OHE(1) or the ratio of 2OHE(1):16alpha-OHE(1.)

Cytochrome P4501A2 (CYP1A2) activity and lung cancer risk: a preliminary study among Chinese women in Singapore.

There is increasing evidence for the role of heterocyclic and other arylamines in carcinogenesis, including lung carcinogenesis. Chinese women have a high rate of lung cancer despite a low smoking prevalence, and studies in this population may provide useful information on risk factors other than smoking. Hepatic CYP1A2 and NAT2 are involved in the metabolism of carcinogenic arylamines, and NAT2 also catalyzes the detoxification pathway for these compounds. In this study, we examined the effect of CYP1A2 activity using a urinary caffeine metabolic ratio assay for 54 Chinese women with newly diagnosed lung cancer (including 28 adenocarcinomas) and 174 hospital controls. Among them, NAT2 genotype was available for 47 cases and 98 controls. There was no effect of CYP1A2 activity on overall risk of lung cancer in the study population [odds ratio (OR) 0.8, 95% confidence interval (CI) 0.4-1.6, adjusted for age at diagnosis, smoking and cruciferous vegetable intake]. For adenocarcinomas, the OR was 1.5, 95% CI 0.6-3.4. After further adjustment for NAT2 acetylator genotype, the OR for adenocarcinoma was 1.8 (95% CI 0.7-4.8). When the combined NAT2/CYP1A2 status was examined, women with slow NAT2 and rapid CYP1A2 activity were at highest risk (adjusted OR 6.9, 95% CI 1.3-37.6) relative to women with rapid NAT2 and slow CYP1A2 activity, for lung adenocarcinoma. While larger studies are needed to confirm or refute these results, they are consistent with a role for heterocyclic arylamines in lung carcinogenesis in this primarily non-smoking population.

Fumes from meat cooking and lung cancer risk in Chinese women.

Chinese women are recognized to have a high incidence of lung cancer despite a low smoking prevalence. Several studies have implicated domestic exposure to cooking fumes as a possible risk factor, although the exact carcinogens have yet to be identified. Heterocyclic amines are known carcinogens, which have been identified in cooked meat, and also in fumes generated during frying or grilling of meats. We conducted a case-control study of 303 Chinese women with pathologically confirmed, primary carcinomas of the lung and 765 controls to examine the association between exposure to meat cooking and lung cancer risk. Data on demographic background, smoking status, and domestic cooking exposure, including stir-frying of meat, were obtained by in-person interview while in hospital. The response rates among eligible cases and controls were 95.0 and 96.9%, respectively. The proportion of smokers (current or ex-smokers) among cases and controls was 41.7 and 13.1%, respectively. Adenocarcinomas comprised 31.5% of cancers among smokers and 71.6% among nonsmokers. When cases were compared with controls, the odds ratio (OR) for lung cancer (all subtypes) among ex-smokers was 4.3 [95% confidence interval (CI) 2.7-6.8] and that among current smokers was 5.0 (95% CI, 3.4-7.3). Among smokers, women who reported that they stir-fried daily in the past had a significantly increased risk of lung cancer (adjusted OR, 2.0; 95% CI, 1.0-3.8) and among these women, risk was enhanced for those who stir-fried meat daily (OR, 2.7; 95% CI, 1.3-5.5). Women who stir-fried daily but cooked meat less often than daily did not show an elevated risk (OR, 1.0. 95% CI, 0.5-2.4). Risk was further increased among women stir-frying meat daily who reported that their kitchen was filled with oily fumes during cooking (OR, 3.7; 95% CI, 1.8-7.5). These cooking practices on their own did not increase risk among nonsmokers in our study population. Our results suggest that inhalation of carcinogens, such as heterocyclic amines generated during frying of meat, may increase the risk of lung cancer among smokers. Further studies in different settings are warranted to examine this possibility, which may also help to explain the higher risk observed among women smokers compared with men.

Attitudes as barriers in breast screening: a prospective study among Singapore women.

Health care systems do not exist in isolation, but rather, as part of the larger social and cultural mosaic. In particular, perceived attitudes are major obstacles in health promotion exercises. This problem is especially true for non-white populations where little is known about the prevailing social and cultural perceptions towards western biomedical prescriptions. To further our understanding of Asian women's acceptance of mammograms, three attitudinal indexes are conceptualised, constructed and validated. Data from a prospective survey showed the significance of fatalistic attitudes, perceived barriers and perceived efficacy of early detection in predicting women's acceptance of a free mammogram at the National Breast Screening Project. In addition, findings reinforced the importance of social support from the family in the promotion of breast screening among Asian women.

Effects of social support, regular physician and health-related attitudes on cervical cancer screening in an Asian population.

OBJECTIVE: Out primary objective was to examine sociodemographic and attitudinal factors that affect uptake of the Pap smear in a multi-ethnic Asian population. METHODS: We conducted a prevalence survey among women aged 50-64 years living in Singapore and ascertained by means of an in-person questionnaire interview their Pap screening history, demographic characteristics, informal social support and attitudes towards early detection. RESULTS: We found that, after adjusting for demographic variables known to be predictors of Pap screening, women who reported ever having a Pap smear were more likely to have close friends with whom they could discuss health (adjusted odds ratio (OR) 2.1, 95% confidence intervals (CI) 1.2-3.6), and have a regular physician (adjusted OR 2.3 (1.3-4.1)). Based on responses to four indices measuring health attitudes, they were significantly less likely to express a fatalistic viewpoint towards health and illness (adjusted OR for highest vs. lowest tertile 0.3 (95% CI 0.1-0.7)), and more likely to believe that early detection could improve the outcome (adjusted OR 3.3 (95% CI 1.4-7.8)). The nature of the test itself was a significant barrier to having a Pap smear, but only among women with fewer years of education. CONCLUSIONS: Our results suggest that, within this Asian population, a multi-pronged approach is required to reach unscreened women. The role of physicians and close friends should be emphasized, and health messages should be formulated to address specific, relevant attitudinal barriers to Pap screening.

Survival of colorectal cancer patients in Singapore by anatomic subsite: a population-based study.

INTRODUCTION: Studies of the prognostic value of anatomic subsite in colorectal cancer survival have yielded conflicting results. Two explanations for possible differences in survival patterns between proximal and distal lesions in the colorectum are biological difference between subsites and the presence of more early-stage lesions in distal than in proximal large bowel. MATERIALS AND METHODS: A total of 435 cases with proximal lesions and an equal number with distal lesions diagnosed between 1990 and 1992 were randomly selected from the Singapore Cancer Registry. Information on vital status at 31 December 1996 were obtained by computerised matching with data from the National Registry of Births and Deaths. RESULTS: Persons with proximal cancers in our study population did not present at a later stage than persons with distal cancer, local lesions (Dukes' Stage A + B) being 45.5% and 45.1%, respectively. Our analysis showed no significant differences in survival between subsites on a stage-for-stage basis. The 5-year survival rates were 42% and 44% for proximal and distal lesions, respectively (median survival times 3.98 and 4.27 years). Stage at diagnosis was the strongest predictor of survival. Among proximal lesions, 5-year survival rates were 57%, 36% and 12% for local, regional and metastatic lesions, respectively. The corresponding figures for the distal group were 65%, 37% and 10%. Age at diagnosis had a significant influence on survival. CONCLUSIONS: Our results, based on population-based figures on survival of colorectal cancer patients where the impact of screening has not been large, do not support an independent influence of anatomic subsite in predicting survival of colorectal cancer.

Correlation between acetylation phenotype and genotype in Chinese women.

OBJECTIVE: The acetylation polymorphism is a common inherited variation in human drug and carcinogen metabolism. Because N-acetyltransferase (NAT2) is important for the detoxification and/or bioactivation of drugs and carcinogens, this polymorphism has important implications in therapeutics and cancer susceptibility. A high correlation between acetylation phenotype and genotype has been demonstrated in several studies. However, no such data exist for Chinese females. The aim of the present study was to compare acetylation phenotype with NAT2 genotype in a population of primarily non-smoking Chinese females. METHODS: In the present study, the correlation between N-acetyltransferase activity and NAT2 genotype was evaluated in 103 unrelated Chinese female controls derived from a hospital-based case-control study of lung cancer in Singapore. Acetylation phenotype and genotype were respectively determined using caffeine and an allele-specific polymerase chain reaction (PCR). RESULTS: The proportions of rapid and slow phenotypes were 78% and 22%, respectively, while the distribution of rapid (heterozygotes and homozygotes combined) and slow acetylator genotypes was 76% and 24%, respectively. The distribution of the various NAT2 genotypes did not differ significantly (chi2 = 1.45, P > 0.05) from that predicted by the Hardy-Weinberg Law. All slow acetylators were accurately predicted (100%), whereas 2 of 80 rapid acetylators were erroneously predicted as slow (2.5%). The overall prediction rate of the PCR-based test for the acetylation phenotype was at 98.1% in our Chinese population. CONCLUSION: Our results suggest that genotyping with PCR may well become the preferred method for the determination of acetylation polymorphism in epidemiological studies in this Asian population.

A cross-sectional survey of physical activity among middle aged women in Singapore.

OBJECTIVES: To assess the extent to which middle-aged women in Singapore engage in physical activity of a level which would result in long-term health benefits, and to determine the factors associated with this. METHODS: We conducted a cross-sectional survey of women aged between 35 and 60 years residing in Marine Terrace. A standardised questionnaire incorporating a modified Seven-Day Recall Questionnaire was used to record the level and type of physical activity engaged in over the past week. Demographic information and factors promoting or discouraging sports and exercise were also elicited. The total energy expenditure for household, occupational and sports activities of moderate intensity and above was calculated using metabolic equivalents (METs) in kcal/kg/week. RESULTS: Of the 341 respondents, 50.7% reported engaging in at least moderate activity for 30 minutes or more every day during the past week, thus fulfilling the WHO recommendations on physical activity. Housework contributed significantly to the energy expenditure on these activities among our target population. After adjusting for age, body mass index and educational level, we found that housewives without domestic help were most likely to fulfill the WHO recommendations. Housewives or working women with domestic help were the two groups at highest risk of low physical activity. A lack of time was the reason most commonly cited for not engaging in sports or exercise. CONCLUSION: Studies assessing physical activity in relation to disease risk among women should include domestic work in addition to the traditional leisure-time activities. There is a scope for further efforts to improve the level of activity in this population, which could be facilitated by the support of health professionals, employers and family members.