Search

Air pollution has shown to cause adverse health effects on mankind. Aging causes functional decline and leaves elderly people more susceptible to health threats associated with air pollution exposure. Elderly spend approximately 80% of their lifetime at home every day. To understand air pollution exposure, indoor air pollutants are the targets for consideration especially for the elderly population. However, indoor air monitoring for epidemiological studies requires a large population, is labor intensive and time consuming. As a result, a prediction model is necessary. For 3 consecutive days in summer and winter, 24-h average of mass concentrations of fine particulate matter (aerodynamic diameter <2.5 μm: PM2.5) were measured in indoors for 116 households. A PM2.5 prediction model for elderly households in Hong Kong has been developed by combining ambient PM2.5 concentrations obtained from land use regression model and questionnaire-elicited information related to the indoor PM2.5 sources. The fitted linear mixed-effects model is moderately predictive for the observed indoor PM2.5, with R(2) = 0.67 (or R(2) = 0.61 by cross-validation). The model shows indoor PM2.5 was positively influenced by outdoor PM2.5 levels. Meteorological factors (e.g. temperature and relative humidity) were related to the indoor PM2.5 in a relatively complex manner. Congested living areas, opening windows for extended periods for ventilation and use of liquefied petroleum gas for cooking were the factors determining the ultimate indoor air quality. This study aims to provide information about controlling household air quality and can be used for future epidemiological studies associated with indoor air pollution in large population.

Background: While the chemoprevention effect of aspirin is well-established, the effects of metformin in cancer prevention is still controversial. This study is to investigate the use of aspirin, metformin, or the combination of both is associated with delayed cancer incidence. Method: This dataset is based on the electronic medical record of public hospitals in Hong Kong. Patients were classified into 1. aspirin user, 2. metformin user, 3. both aspirin and metformin user and 4. control group with neither aspirin nor metformin used. Aspirin and/or metformin must have been taken for over 6 months in the treatment group and cancer incidences was counted at least 6 months after exposure to such medications. The primary outcome of this study was overall incidence of cancer during the follow-up period. The secondary outcomes were cancer incidences of specific sites, including colon/rectum, liver, oesophagus, pancreas, stomach, lung, breast, kidney, bladder and prostate. Cox proportional hazards regression models were fitted to estimate hazard ratios of cancer risks. Inverse probability of treatment weighting was used to control for the medication effects. Results: A total of 120,971 aspirin users, 11,365 metformin users, and 6630 aspirin plus metformin users, were identified. Compare to the control groups, those who used aspirin alone demonstrated a significant reduction in overall cancer risk (HR 0.80, 95% CI 0.73-0.87). Similarly, those who used metformin alone also showed an overall reduction in cancer risk (HR 0.79, 95% CI 0.71-0.88). Patients who received both aspirin and metformin showed the most significant reduction in overall cancer risk (HR 0.53, 95% CI 0.45-0.63). Metformin showed a significant reduction in cancer risk of lung, oesophagus and bladder. Conclusion: There is a similar decrease in overall cancer rate with the use of aspirin or metformin alone. A more significant reduction in overall cancer risk was found with the use of both agents.

Background and Aim: The chemopreventive effect of aspirin in colorectal cancer (CRC) is well studied, but its benefit in patients after CRC diagnosis and surgery is unclear. This study aims to investigate the effects of low-dose aspirin use in mortality among CRC patients after surgery. Methods: Patients were analyzed in two cohorts: (i) patients taking aspirin before CRC diagnosis and continued or discontinued aspirin after surgery and (ii) patients, who never used aspirin before CRC diagnosis, received or did not receive aspirin after surgery. CRC-related mortality and all-cause mortality were the primary and secondary outcomes. Sub-distribution hazard ratio (SHR) for competing-risk CRC mortality was fitted to adjust for other causes of death; hazard ratio (HR) was used to compare all-cause mortality. Results: A total of 13 528 CRC patients were included. Among 3292 patients with regular aspirin use before CRC diagnosis, 2658 (80.7%) continued aspirin and 634 (19.3%) discontinued aspirin after surgery. Continuous use of aspirin significantly reduced CRC-related mortality (SHR: 0.69, 95% confidence interval [CI]: 0.59–0.81) and all-cause mortality (HR: 0.61, 95% CI: 0.55–0.68). Among 10 236 patients who did not use aspirin before CRC diagnosis, 1054 patients (10.3%) received aspirin after surgery and 9182 (89.7%) did not. Aspirin initiated after surgery reduced CRC-related mortality (SHR: 0.88, 95% CI: 0.80–0.98) and all-cause mortality (HR: 0.87, 95% CI: 0.81–0.94). Conclusions: Irrespective of aspirin use before surgery for CRC, low-dose aspirin after surgery lowers risk of both CRC-related mortality and overall mortality.

Background: Colorectal cancer incidence among young adults in the United States is on the rise, but whether this phenomenon is present in other parts of the world is not well documented. This study aims to explore the temporal change of incidence rates for colorectal cancer in various countries across the globe. Methods: We extracted colorectal cancer incidence and population data from 1988 to 2007 based on data from the International Agency for Research on Cancer and compared incidence between age groups. Twelve representative jurisdictions from five continents were selected. Young-onset colorectal cancer cases were defined as those ages <50 years. Joinpoint regression was used to measure the trends of colorectal cancer incidence and to estimate the annual percent change (APC). Results: The APC for those ages <50 years was noted to be increasing at a faster rate as compared with those ages ≥50 years in many regions, including Australia (+1.10% vs. −0.35%), Brazil (+9.20% vs. +5.72%), Canada (+2.60% vs. −0.91%), China–Hong Kong (+1.82% vs. −0.10%), China–Shanghai (+1.13% vs. −2.68%), Japan (+2.63% vs. +0.90%), the United Kingdom (+3.33% vs. +0.77%), and the United States (+1.98% vs. −2.88%). These trends were largely driven by rectal cancer, except in Brazil and the United Kingdom. Conclusions: Increasing incidence of young-onset colorectal cancer was noted in many regions across the globe. Impact: Further studies focusing on young-onset colorectal cancer, particularly with regard to risk factors and establishing the optimal age of screening, are warranted.

Aspirin, commonly used for prevention of cardiovascular and cerebrovascular diseases, has been found to possess protective effects against cancer development in the Western populations. Such effects among Asian populations remain uncertain. The objective of this study is to investigate the use of aspirin on prevention of different cancers among Chinese users. This population-based study utilized database from the Hong Kong Hospital Authority; adults with aspirin prescription for at least 6 months between 2000 and 2004 were included and followed up until 2013. Aspirin users were age-sex matched with non-aspirin users at a 1:2 ratio. Incidences of cancer were the primary outcome measured by relative risk (RR). A total of 204,170 aspirin users and 408,339 non-aspirin users were included, with the mean age 67.5 years, 7.7 years average duration of aspirin prescription and 80 mg as the median dose of aspirin. Cancer incidences were found in 26,929 (13.2%) aspirin users and 70,755 (17.3%) non-aspirin users. Compared with patients who had not been prescribed aspirin, aspirin usage led to significant reduction of cancers in liver (RR: 0.49), stomach (RR: 0.42), colorectum (RR: 0.71), lung (RR: 0.65), pancreas (RR: 0.54), oesophagus (RR: 0.59) and leukaemia (RR: 0.67). There was no demonstrable reduction of kidney cancer, bladder cancer, prostate cancer and multiple myeloma in association with the usage of aspirin. Risk of breast cancer was shown to marginally increase (RR: 1.14) with aspirin usage. This study demonstrated that the long-term use of low-dose aspirin is associated with the reduction in risk of various cancers but not for breast cancer. Further investigation is needed before promoting aspirin as a primary chemoprotective agent.

To investigate the global incidence of prostate cancer with special attention to the changing age structures. Data regarding the cancer incidence and population statistics were retrieved from the International Agency for Research on Cancer in World Health Organization. Eight developing and developed jurisdictions in Asia and the Western countries were selected for global comparison. Time series were constructed based on the cancer incidence rates from 1988 to 2007. The incidence rate of the population aged ≥ 65 was adjusted by the increasing proportion of elderly population, and was defined as the “aging-adjusted incidence rate”. Cancer incidence and population were then projected to 2030. The aging-adjusted incidence rates of prostate cancer in Asia (Hong Kong, Japan and China) and the developing Western countries (Costa Rica and Croatia) had increased progressively with time. In the developed Western countries (the United States, the United Kingdom and Sweden), we observed initial increases in the aging-adjusted incidence rates of prostate cancer, which then gradually plateaued and even decreased with time. Projections showed that the aging-adjusted incidence rates of prostate cancer in Asia and the developing Western countries were expected to increase in much larger extents than the developed Western countries.