Lap-Ah Tse

Previous pulmonary disease and family cancer history increase the risk of lung cancer among Hong Kong women.

Chinese women in Hong Kong have among the highest incidence and mortality of lung cancer in the world, in spite of a low prevalence of smoking. We carried out this population-based case–control study to evaluate the associations of previous lung disease and family cancer history with the occurrence of lung cancer among them. We selected 212 cases that were newly diagnosed with primary lung cancer, and randomly sampled 292 controls from the community, frequency matched by age group. All the cases and controls were lifetime nonsmokers. We estimated the main effects of preexisting asthma, pulmonary tuberculosis, pneumonia, chronic bronchitis, and family lung/all cancer history, using unconditional logistic regression, accounting for various potential risk factors and confounders. All of the previous lung diseases, except chronic bronchitis, were related to an elevated risk for lung cancer, and the association with asthma was significant. Those who had more than one previous lung disease tended to be at higher risk than those with only one of them. Positive family history of any cancer was associated with over 2-fold risk than negative family history. The joint effect of positive history of previous pulmonary diseases and positive family cancer history appeared to be additive, indicating the two factors acted independently. The results support an etiological link of preexisting lung disease and family cancer history to the risk of lung cancer.

Cancer mortality among Chinese chrysotile asbestos textile workers.

To determine mortality associated with exposure to chrysotile asbestos, a cohort of asbestos workers from an asbestos textile factory in China was followed prospectively from 1972 to 2008. A total 577 workers were successfully followed, achieving a follow-up rate of 98.5% over 37 years. Employment data and smoking information were obtained from factory and individual workers. Vital status was ascertained from factory personnel records and the municipal death registry. Workers were categorized into high, medium and low exposure groups in terms of their job titles and workshops. Follow-up generated 17,508 person-years, with 259 deaths from all causes, 96 all cancers and 53 lung cancers and 2 mesotheliomas. The highest cancer mortality was observed in the high exposure group, with 1.5-fold age-adjusted mortality from all cancers and 2-fold from lung cancer compared to the low exposure group. Age and smoking adjusted hazard ratio in the high exposure group was 2.99 (95%CI, 1.30, 6.91) for lung cancer and 2.04 (1.12, 3.71) for all cancers. Both smokers and nonsmokers at the high exposure level had a high death risk of lung cancer, with a clearer exposure-response trend seen in smokers. This study confirmed increased mortality from lung cancer and all cancers in asbestos workers, and the cancer mortality was associated with exposure level.

Occupational health and safety challenges in China-focusing on township-village enterprises

ABSTRACT China has experienced dramatic industrialization, urbanization, and economic growth over the last 3 decades. The rapid transformation and dramatic prosperity of industries in rural areas have, in turn, created tremendous challenges for occupational health and safety (OHS). This article was prepared to address occupational health and safety issues in township- and village-owned enterprises (TVEs) from several aspects, including working conditions and workplace hazards, major recognized OHS problems, implications of TVE industries to environmental health, and migrant workers. Among the major recognized OHS problems, pneumoconiosis, chemical poisoning, and workplace accidents, especially in small-scale coal mines, are highlighted. It is suggested that the national polices and regulations that specifically target TVEs are indispensable and a more powerful administrative structure should be established to ensure that the pertinent polices, regulations, and OHS standards can be enforced widely and effectively in practice.

Sex difference in the incidence of nasopharyngeal carcinoma in Hong Kong 1983–2008: Suggestion of a potential protective role of oestrogen

BACKGROUND Nasopharyngeal carcinoma (NPC) shows a male predominance in incidence while the underlying reasons have rarely been explored. METHODS We analysed incident cases of NPC recorded in Hong Kong Cancer Registry during the period 1983-2008. All cases were divided into 5-year age groups. Age group specific incidence rates of NPC by sex and male to female ratios in incidence rate by age group were calculated. A curve fitting approach was taken to quantitatively describe the age-specific incidence rates of NPC using non-linear regressions. RESULTS During the period 1983-2008, a total of 27,579 new cases of NPC were identified (20,060 males and 7519 females) in Hong Kong. The overall male to female ratio of the annual age-standardised incidence rates of NPC ranged 2.2-3.1. The male to female ratio of NPC incidence increased with age until peaking at ages 55-59 years and showed a decline thereafter. An additional minor increase at ages 15-19 years was also observed. Modelling of the age-specific incidence curves suggested divergent slopes for men and women and a delay in increasing incidence with age among females, by around 5-10 years before menopause ages. CONCLUSION The age-dependent pattern of the sex difference in the incidence of NPC could not be completely explained by known risk factors for NPC. The contributions of intrinsic exposures, such as sex hormones, merit consideration and further investigations.

Time trends of esophageal cancer in Hong Kong : Age, period and birth cohort analyses

This study was to examine the time trend of the incidence rates of esophageal cancer during the period 1979–2003 in Hong Kong and to identify the effects of year of diagnosis (period) and year of birth (cohort) on the observed time trends using regression models. Cancer incidence data were obtained from Hong Kong Cancer Registry and population data were from the Census and Statistics Department. Age‐standardized incidence rates were computed by the direct method using the World population of 1966. Annual percentage change (APC) in incidence rate was calculated using nonlinear regression. Period and cohort effects were assessed using 2 separate Poisson regression models after adjusting for age. During the period 1979–2003, a steady decrease in the age‐standardized incidence rate was observed for both males (APC = −3.38%, 95% confidence interval [CI]: −2.89%, −3.86%) and females (APC = −3.92%, 95% CI: −3.15%, −4.69%). The incidence rates were consistently higher among males than females. After the adjustment for age and with the period 1989–1993 or birth cohort of 1934–1938 as reference, the relative risk of more recent periods or birth cohorts significantly decreased. The age‐cohort model provided a better description of the data than the age‐period model. Given reasonable latency between exposures and esophageal cancer incidence, the declining birth cohort effects in the recent generations were in line with the increased intakes of fresh vegetables and decreased consumptions of alcohol drinking, tobacco smoking, and preserved foods observed in population, thus supported their importance in influencing the burden of esophageal cancer.

Time trends and age-period-cohort analyses on incidence rates of nasopharyngeal carcinoma during 1993-2007 in Wuhan, China.

BACKGROUND Declines in incidence rates of nasopharyngeal carcinoma (NPC) were observed in Hong Kong and Taiwan but not other high-risk regions in China, while evidences from low-risk regions in China are still lacking. This study aimed to examine the time trends (1993-2007) of NPC in Wuhan (a low-risk region) and assess the birth cohort and calendar period effects on the observed temporal trends. METHOD Using data from Wuhan Cancer Registry, age-standardized annual incidence rates of NPC were calculated by the direct method using the WHO World Standard Population (2000) as the reference. Trend in incidence rates of NPC during 1993-2007 was evaluated. Age-period-cohort models were also applied to assess the effects of age, calendar time and birth cohort on the observed temporal trends. RESULTS A total of 1685 new NPC cases (1210 males and 475 females) were diagnosed during 1993-2007 in Wuhan. The annual percentage change in incidence rates of NPC were 0.15% (95% confidence interval: -3.88% to 4.34%) for males and -1.17% (95% confidence interval: -4.85% to 2.66%) for females. No obvious cohort or period effect on the incidence rates of NPC was observed. CONCLUSION The incidence rates of NPC remained stable during 1993-2007 in Wuhan, a low-risk region in China.

Frequent use of household cleaning products is associated with rhinitis in Chinese children

BACKGROUND Despite the popular use of household cleaning products worldwide, there is no published study investigating the health effects of these products on rhinitis in children. OBJECTIVE We sought to investigate the household use of cleaning products and rhinitis patterns in Chinese children. METHODS A total of 2299 children were recruited from 21 primary schools with wide geographic coverage in Hong Kong. Self-administered questionnaires were completed by parents/guardians to collect detailed information on respiratory symptoms and household use of 14 types of chemical cleaning products, as well as clean water. Students were categorized into 4 mutually exclusive rhinitis patterns (never, occasional, frequent, and persistent). The total chemical burden (TCB) score was used as the exposure indicator by calculating the total time of exposure to the 14 cleaning products. Multinomial logistic regression was used to assess the relationship between rhinitis patterns and the use of household cleaning products. RESULTS Every 10-unit increment of TCB score was associated with an increase in the odds of occasional (odds ratio [OR], 1.21; 95% CI, 1.05-1.41), frequent (OR, 1.36; 95% CI, 1.13-1.60), and persistent (OR, 1.21; 95% CI, 1.01-1.56) rhinitis after adjustment for a wide range of potential confounders. Compared with the children within the lowest tertile of TCB scores, the adjusted ORs of occasional, frequent, and persistent rhinitis in children within the highest tertile were 1.29 (95% CI, 1.01-1.65), 1.97 (95% CI, 1.40-2.76), and 1.67 (95% CI, 1.10-2.54), respectively. CONCLUSION Frequent use of chemical cleaning products at home is associated with an increase in the odds of rhinitis in Chinese primary school children.

Occupational Lung Cancer

The lungs are the most common site for primary cancers in humans. This chapter focuses on examining occupational cancers in the parenchyma of the lungs, and starts with a historical review on the identification of lung carcinogens in various occupational groups. Occupational lung cancer linked to radon was first described in 1879. Various occupational exposures were subsequently found to increase the risk of lung cancer. Of the 107 agents classified by the International Agency for Research on Cancer (IARC) as Group 1 (confirmed human) carcinogens, 26 are regarded as carcinogens for lung cancers, and all except two mainly involve occupational exposures. Exposure to occupational carcinogens is an important determinant of lung cancer death and disability globally. Estimates on the contribution of occupational cancers to the population disease burden of lung cancer (population attributable fractions) ranged from 0.6 to 40%, depending on the population or geographical location, which might be explained by the different mix of industries and exposures. When examining the possible etiologic associations between occupational exposures and lung cancer, the effect of smoking should be carefully examined, as smoking is the most important cause for lung cancer in most countries, and exposures to occupational lung carcinogens not infrequently coexist with smoking. Smoking can act as a confounder or can modify the effects of occupational lung carcinogens. Lung cancers are irreversible and self-propagating, usually with poor prognosis, and hence should best be prevented. For occupational cancer, primary prevention is most relevant and has been found to be very successful in the past. Removing the agent, through elimination or substitution of known carcinogens, is most effective. Exposure can also be reduced through engineering and administrative means by modification of the plant, the working environment or the work process.

The impact of breast cancer-specific birth cohort effects among younger and older Chinese populations

Historically low breast cancer incidence rates among Asian women have risen worldwide; purportedly due to the adoption of a “Western” life style among younger generations (i.e., the more recent birth cohorts). However, no study has simultaneously compared birth cohort effects between both younger and older women in different Asian and Western populations. Using cancer registry data from rural and urban China, Singapore and the United States (1990–2008), we estimated age‐standardized incidence rates (ASR), annual percentage change (EAPC) in the ASR, net drifts, birth cohort specific incidence rates and cohort rate ratios (CRR). Younger (30–49 years, 1943–1977 birth cohorts) and older women (50–79 years; 1913–1957 birth cohorts) were assessed separately. CRRs among Chinese populations were estimated using birth cohort specific rates with US non‐Hispanic white women (NHW) serving as the reference population with an assigned CRR of 1.0. We observed higher EAPCs and net drifts among those Chinese populations with lower ASRs. Similarly, we observed the most rapidly increasing cohort‐specific incidence rates among those Chinese populations with the lowest baseline CRRs. Both trends were more significant among older than younger women. Average CRRs were 0.06–0.44 among older and 0.18–0.81 among younger women. Rapidly rising cohort specific rates have narrowed the historic disparity between Chinese and US NHW breast cancer populations particularly in regions with the lowest baseline rates and among older women. Future analytic studies are needed to investigate risk factors accounting for the rapid increase of breast cancer among older and younger women separately in Asian populations.

Residual beneficial effects after a 3-year integrated intervention on stroke in China: a 10-year prospective follow-up.

Objectives To evaluate whether an intervention program designed to reduce stroke incidence would have long-term residual effects on reducing all-cause and cause-specific mortalities, including cancer 10 years after the intervention was completed. Methods This is a posttrial analysis. We prospectively observed the mortality of a community-based trial of primary prevention of stroke in China performed between July 1987 and June 1990 by extending the follow-up to 30 June 2000. At the baseline, 26 607 adults aged 35 years or above and free from stroke were recruited from five cites of mainland China; 13 212 and 13 395 were assigned into intervention and control group, respectively. Participants in intervention group received a regularly integrated intervention including lifestyle intervention and hypertensive drug treatment. The controls did not receive intervention provided by the investigators. Results During the 10-year posttrial follow-up period, we observed a significant reduction on overall deaths [hazard ratio 0.91; 95% confidence interval (CI) 0.83, 0.99] and stroke mortality (hazard ratio 0.79; 95% CI 0.63, 1.00). An insignificant late trial beneficial effect was observed for hypertensive disease (hazard ratio 0.69; 95% CI 0.30, 1.58), ischemic heart disease (hazard ratio 0.87; 95% CI 0.64, 1.17), other nonmalignant diseases, and most cancer sites. Conclusion This study demonstrates that a 3-year integrated intervention program successful for stroke prevention had long-term residual beneficial effects on reducing overall disease burdens among urban Chinese population, especially for the deaths from stroke. However, whether the integrated intervention also leads to reduced mortality of cardiovascular diseases and cancer would have to be confirmed by future larger studies.