C. M. Wong

Trends in breast cancer incidence in Hong Kong between 1973 and 1999: an age-period-cohort analysis.

Hong Kong has the highest breast cancer incidence in Asia and studying secular changes in its rates may lead to hypotheses regarding disease aetiology and also predictions of future trends for China. We examined statistics from the Hong Kong Cancer Registry based on 26 566 cases of invasive breast cancer from 1973 to 1999. The trends in breast cancer incidence were studied using log-linear longitudinal models. We further analysed the independent effects of chronological age, time period and birth cohort on incidence trends using age-period-cohort modelling. The average annual per cent change of the age-standardised incidence was 3.6% during 1973–1999. Age-period-cohort modelling indicated the incidence development was predominantly a cohort effect, where the rise in relative risk was seemingly linear in successive birth cohorts, showing a 2–3-fold difference when comparing women born in the 1960s with those born around 1900. Our results suggest that direct and indirect consequences of westernisation may have been responsible for most of the observed increase in breast cancer incidence. As China moves towards a more westernised way of life, we can expect an emerging epidemic of breast cancer as Hong Kongs experience has demonstrated.Hong Kong has the highest breast cancer incidence in Asia and studying secular changes in its rates may lead to hypotheses regarding disease aetiology and also predictions of future trends for China. We examined statistics from the Hong Kong Cancer Registry based on 26 566 cases of invasive breast cancer from 1973 to 1999. The trends in breast cancer incidence were studied using log-linear longitudinal models. We further analysed the independent effects of chronological age, time period and birth cohort on incidence trends using age-period-cohort modelling. The average annual per cent change of the age-standardised incidence was 3.6% during 1973–1999. Age-period-cohort modelling indicated the incidence development was predominantly a cohort effect, where the rise in relative risk was seemingly linear in successive birth cohorts, showing a 2–3-fold difference when comparing women born in the 1960s with those born around 1900. Our results suggest that direct and indirect consequences of westernisation may have been responsible for most of the observed increase in breast cancer incidence. As China moves towards a more westernised way of life, we can expect an emerging epidemic of breast cancer as Hong Kongs experience has demonstrated.

Understanding the Spatial Clustering of Severe Acute Respiratory Syndrome (SARS) in Hong Kong

We applied cartographic and geostatistical methods in analyzing the patterns of disease spread during the 2003 severe acute respiratory syndrome (SARS) outbreak in Hong Kong using geographic information system (GIS) technology. We analyzed an integrated database that contained clinical and personal details on all 1,755 patients confirmed to have SARS from 15 February to 22 June 2003. Elementary mapping of disease occurrences in space and time simultaneously revealed the geographic extent of spread throughout the territory. Statistical surfaces created by the kernel method confirmed that SARS cases were highly clustered and identified distinct disease “hot spots.” Contextual analysis of mean and standard deviation of different density classes indicated that the period from day 1 (18 February) through day 16 (6 March) was the prodrome of the epidemic, whereas days 86 (15 May) to 106 (4 June) marked the declining phase of the outbreak. Origin-and-destination plots showed the directional bias and radius of spread of superspreading events. Integration of GIS technology into routine field epidemiologic surveillance can offer a real-time quantitative method for identifying and tracking the geospatial spread of infectious diseases, as our experience with SARS has demonstrated.

Factors Influencing Smoking Behavior in Hong Kong Primary Schoolchildren: Targets for Prevention

The uptake of smoking by children and factors influencing such behavior, although well documented in the West, have not been studied in the Asia-Pacific region. A cross-sectional survey was carried out on 3, 521 children, aged 8-11 years living in two districts of Hong Kong. Knowledge, attitude and behavior related to smoking and sociodemographic data were obtained from questionnaires completed by parents and children. Eleven percent of boys and 5 percent of girls were ever-smokers, 5 percent of all eight-year-olds and 21 percent of 11-year-olds. Believing that parents will not interfere with their smoking (adjusted odds ratio 5.52; 95% confidence interval 2.72, 11.18), living with family members who smoke (1.72; 1.33, 2.23), and having a positive attitude to smoking (4.13; 1.43, 11.98) were factors predictive of ever-smokers. Experimentation with smoking is a major health risk for primary school children in Hong Kong and indicates failure of current smoking prevention programs. Effective culture-specific programs to counteract risk factors and with continuing evaluation are urgently needed; they should be based on information from appropriately-designed epidemiological studies.

Health impact assessment of marine emissions in Pearl River Delta region.

Global marine vessels emissions are adversely affecting human health particularly in southeast Asia. But health burdens from both ocean- and river-going vessels in Pearl River Delta (PRD) regions are not quantified. We estimated the potential health impacts using pooled relative risks of mortality and hospital admissions in China, and the model derived concentrations of sulfur dioxide (SO₂), particulate matter (PM₁₀), nitrogen dioxide (NO₂) and ozone (O₃) due to vessels emissions. SO₂ concentrations due to marine emissions in Hong Kong were 13.6 μg m⁻³ compared with 0.7 μg m⁻³ in PRD regions that were far from the marine vessels. In PRD regions, the estimated annual numbers (per million people) of excess deaths from all natural causes and hospital admissions from cardiorespiratory causes attributable to SO₂, NO₂, O₃ and PM₁₀ combined from marine emissions were 45 and 265 respectively. Marine emission control measures could contribute a large reduction in mortality and hospital admissions in PRD regions especially in Hong Kong.

A Smoking Intervention Programme for Primary School Students in Hong Kong

This study was designed to evaluate a smoking prevention programme targeted at primary school children. The objectives were to: 1) assess the feasibility of the programme; 2) increase the children’s awareness of the purposes of tobacco advertising; 3) record any change in attitude towards smoking and 4) measure the effects on the children’s knowledge about the harmful effects of smoking.

Tobacco advertisements were associated with positive attitudes to smoking among children who had never smoked

Many studies have shown that tobacco advertisements and positive attitudes to smoking, as well as other factors such as family smoking and peer influence, are associated with the smoking behaviour of children. In our cross-sectional study on 6304 junior secondary-school students (forms 1–3, aged mainly 12–15 years), we found that the students’ perception of cigarette advertisements as attractive was strongly associated with smoking experience (Lam et al., 1994). Other factors associated with any smoking were knowledge about the hazards of smoking, positive attitudes to smoking and smoking by the family, schoolteachers and peers (Lam et al., 1995). The association was examined in this and other studies by comparing children who smoked with children who did not. All the risk factors, such as attitudes to smoking, were treated as independent variables, whereas smoking (yes versus no) was the dependent variable. Few studies have addressed children who have never smoked and the factors associated with positive attitudes (as the dependent variables). The aim of this study was to examine factors associated with positive attitudes to smoking among children who had never smoked from the above-mentioned data on 6304 students.

Passive smoking and respiratory symptoms in never smoking women in Hong Kong

In 1989, a cross-sectional survey on primary school children in Hong Kong showed that air pollution (outdoor) and ETS had independent adverse effects on respiratory health.1 This study was aimed to study the relationship between passive smoking and respiratory symptoms in never-smoking mothers of the primary school children in the 1989 survey.

Smoking and lung function in Hong Kong Chinese schoolchildren

The association between tobacco smoking and diseases of the respiratory system, such as chronic obstructive lung disease and lung cancer, is well recognized in adults, as is its association with respiratory ill health in children who are exposed to environmental tobacco smoke (Environmental Protection Agency, 1992). The effect of exposure to tobacco smoke on lung function is less clear. Lower values for forced expiratory volume (FEV) have been reported for children living with parents who smoke (Hasselblad et al., 1981; Vedal et al., 1984; O’Connor et al., 1987; Kauffman et al., 1989), but not necessarily with parallel change in functional vital capacity (FVC) (Kauffman et al., 1989). Gold et al. (1996) found larger values for both FVC and FEV in children who smoked than those who did not, but the rates of growth in lung function were reduced in the smokers (Lebowitz et al., 1987; Gold et al., 1996). This paper presents the results of a preliminary examination of lung function in Chinese primary school children according to the children’s exposure to tobacco smoke.

Environmental tobacco smoke, air pollution and respiratory symptoms in non-smoking housewives in Hong Kong

In Hong Kong, environmental tobacco smoke at home is an important source of air pollution because of the crowded conditions in which most families live. Its effects on the respiratory health of children were shown in a four-year study in 1989–92 (Ong et al., 1991; Peters et al., 1996). The aim of the present study was to examine the effects of environmental tobacco smoke and air pollution on the respiratory health of nonsmoking housewives.

Variation in Smoking Behaviour in a 4-Year Cohort Study of Respiratory Health in Hong Kong Children

Official statistics about young children smoking were previously unavailable in Hong Kong as the method used to obtain information on smoking habits through the General Household Survey was unsuitable for this purpose. In a four-year longitudinal study of respiratory health in two districts of Hong Kong, a cohort of students was surveyed each year, from Primary 3 in 1989 to Primary 6 in 1992.1 The smoking habits (together with other health and life style factors) were observed repeatedly. It provided an opportunity to study the uptake of smoking for the young children and examine the contributing factors. However in such studies care must be taken to identify possible reporting errors by very young children. The main objective of this article was to evaluate the reliability of the data obtained.