Kar Keung Cheng

Physical activity for cancer survivors: meta-analysis of randomised controlled trials

Objective To systematically evaluate the effects of physical activity in adult patients after completion of main treatment related to cancer. Design Meta-analysis of randomised controlled trials with data extraction and quality assessment performed independently by two researchers. Data sources Pubmed, CINAHL, and Google Scholar from the earliest possible year to September 2011. References from meta-analyses and reviews. Study selection Randomised controlled trials that assessed the effects of physical activity in adults who had completed their main cancer treatment, except hormonal treatment. Results There were 34 randomised controlled trials, of which 22 (65%) focused on patients with breast cancer, and 48 outcomes in our meta-analysis. Twenty two studies assessed aerobic exercise, and four also included resistance or strength training. The median duration of physical activity was 13 weeks (range 3-60 weeks). Most control groups were considered sedentary or were assigned no exercise. Based on studies on patients with breast cancer, physical activity was associated with improvements in insulin-like growth factor-I, bench press, leg press, fatigue, depression, and quality of life. When we combined studies on different types of cancer, we found significant improvements in body mass index (BMI), body weight, peak oxygen consumption, peak power output, distance walked in six minutes, right handgrip strength, and quality of life. Sources of study heterogeneity included age, study quality, study size, and type and duration of physical activity. Publication bias did not alter our conclusions. Conclusions Physical activity has positive effects on physiology, body composition, physical functions, psychological outcomes, and quality of life in patients after treatment for breast cancer. When patients with cancer other than breast cancer were also included, physical activity was associated with reduced BMI and body weight, increased peak oxygen consumption and peak power output, and improved quality of life.

A case-control study of oesophageal adenocarcinoma in women: a preventable disease

The incidence of adenocarcinoma of the oesophagus in British women is among the highest in the world. To investigate its aetiology, we conducted a multi-centre, population based case–control study in four regions in England and Scotland. We included 74 incident cases in women with histologically confirmed diagnoses of adenocarcinoma of the oesophagus, and 74 female controls matched by age and general practice. High body mass index (BMI) around the age of 20 years (highest vs lowest quartile, adjusted odds ratio (OR) = 6.04, 95% confidence interval (CI) 1.28–28.52) and low consumption of fruit (highest vs lowest quartile, adjusted OR = 0.08, 95% Cl 0.01–0.49) were associated with increases in risk. Breastfeeding by women was associated with reduced risk of their subsequently developing this cancer (ever vs never, adjusted OR = 0.41, 95% CI 0.20–0.82) and there was a significant dose–response effect with total duration of breastfeeding. The summary population attributable risk from these three factors was 96% (90% if breastfeeding is excluded). We conclude that high BMI in early adulthood and low consumption of fruit are important risk factors for adenocarcinoma of the oesophagus. Breastfeeding may confer a protective effect but this needs confirmation. This cancer is a largely preventable disease in women.

Reliability and validity of the IPAQ-Chinese: the Guangzhou Biobank Cohort study.

INTRODUCTION Valid measurements of self-reported physical activity are very limited in Chinese populations, especially the elderly. Therefore, we examined the validity and reliability of the Chinese version of the International Physical Activity Questionnaire (IPAQ-C) in older Chinese people. METHODS Two hundred twenty-four older adults (66.1% women, 33.9% men, mean age 65.2 +/- 5.7 yr) were randomly selected from the Guangzhou Biobank Cohort Study, a prospective cohort of older Chinese in Southern China. To examine the test-retest reliability, the participants completed the IPAQ-C twice during a 7-d interval. The criterion validity of the IPAQ-C was tested with pedometry. RESULTS Good reliability was observed between the repeated IPAQ-C, with intraclass correlation coefficients (ICC) ranging from 0.81 to 0.89. Total activity measured by IPAQ-C correlated moderately with the pedometer-measured steps (partial r = 0.33 adjusted for sex, age, and education; P < 0.001). The walking domain of IPAQ-C was strongly associated with the number of steps (partial r = 0.58, P < 0.001), but there were no significant associations between other activity domains of the IPAQ-C and the pedometer data. CONCLUSION This is the first reported validation study of an international standardized questionnaire (IPAQ-C) in older Chinese adults. Our study shows that the IPAQ-C is adequately valid and reliable for assessing total physical activity and that it may be a useful instrument for generating internationally comparable data on physical activity in this population.

Nutrition and esophageal cancer

Epidemiologic evidence on the relation between nutrition and esophageal cancer is reviewed. Results from ecologic, case-control, cohort, and intervention studies are included. Most of the findings pertain more to squamous cell carcinoma than adenocarcinoma of the esophagus. The protective effect of fruit and vegetable consumption is supported by a large body of evidence, especially from case-control studies. The effects of food groups and nutrients other than fruits and vegetables also have been examined, but the overall evidence is less convincing. Recent intervention studies in high incidence areas in China indicate that micronutrient supplements may have a modest effect in reducing risk, but the generalizability of this result is uncertain. Hot drinks are likelyto increase the risk of esophageal cancer. On the other hand, the role of tea drinking, especially the use of green tea, remains to be defined better.

Risk factors for squamous cell carcinoma of the oesophagus in women: a case–control study

Oesophageal cancer rates in women in the UK are more than 3 times higher than in most other European populations. A population-based matched case–control study of histologically confirmed squamous cell carcinoma of the oesophagus in women was carried out in 4 regions in England and Scotland. Interviews were carried out in hospital or at home and topics included: smoking; alcohol; tea and coffee consumption; medical and obstetric history; and diet. Response rates were 62% for cases and 65% for first-chosen controls. There were 159 case–control pairs. Significant results were found for: eating salads (odds ratio (OR) 0.42, 95% CI 0.20–0.92 in the highest quartile of consumption) and a light (as distinct from no) breakfast (OR 0.18, 95% CI 0.07 – 0.48) were protective; quantity of tea was a risk factor and there was a significant positive trend with temperature at which hot drinks were consumed (P = 0.03). Alcohol consumption was unrelated to risk, but there was a significant trend with years of smoking (P = 0.015). A protective effect of aspirin consumption was confined to the English centres (OR 0.08, 95% CI 0.01–0.56). Comparison with a parallel study of adenocarcinoma indicated a common protective effect of a healthy diet but otherwise distinct risk factors.

Age of menarche and the metabolic syndrome in China.

Objectives: In western populations, young age of menarche is associated with increased cardiovascular risk. Little is known about the potential impact of menarche on the metabolic syndrome (as a proxy for cardiovascular risk) in rapidly economically developing populations where age of menarche is falling. We sought to determine the relation between age of menarche and the metabolic syndrome in a rapidly developing Chinese population. Methods: We carried out a retrospective historical cohort study of 7349 women from the Guangzhou Biobank Cohort Study, China, enrolled in 2003–2004. Cardiovascular risk factors were obtained from physical examination; age of menarche was obtained from self-report. The main outcome measure was the metabolic syndrome and its components. Results: Adjusted for age, education, and number of pregnancies, young age of menarche (<12.5 years) compared with age of menarche ≥14.5 years was associated with a higher risk of the metabolic syndrome (odds ratio = 1.49; 95% confidence interval = 1.22–1.82), central obesity (1.35; 1.10–1.65), raised blood pressure (1.34; 1.09–1.65), raised fasting glucose (1.40; 1.15–1.71), and higher triglyceride levels (1.36; 1.12–1.67). Further adjustment by waist circumference attenuated these effects, but the odds ratios remained elevated. Conclusions: Earlier age of menarche experienced by younger women in China today, now 12.5 years on average in urban populations, may contribute to an increase in the metabolic syndrome and thereby an increase in cardiovascular disease as these women age. These results further highlight the importance of childhood antecedents of adulthood disease.

Prior TB, Smoking, and Airflow Obstruction: A Cross-Sectional Analysis of the Guangzhou Biobank Cohort Study

BACKGROUND Prior pulmonary TB has been shown to be associated with a higher risk of airflow obstruction, which is the hallmark of COPD, but whether smoking modifies this relationship is unclear. We investigated the relationships between prior TB, smoking, and airflow obstruction in a Chinese population sample. METHODS Participants in the Guangzhou Biobank Cohort Study underwent spirometry, chest radiography, and a structured interview on lifestyle and exposures. Prior TB was defined as the presence of radiologic evidence suggestive of inactive TB. Airflow obstruction was based on spirometric criteria. RESULTS The prevalence of prior TB in this sample (N = 8,066, mean age: 61.9 years) was 24.2%. After controlling for sex, age, and smoking exposure, prior TB remained independently associated with an increased risk of airflow obstruction (odds ratio = 1.37; 95% CI, 1.13-1.67). Further adjustment for exposure to passive smoking, biomass fuel, and dust did not alter the relationship. Smoking did not modify the relationship between prior TB and airflow obstruction. CONCLUSIONS Prior TB is an independent risk factor for airflow obstruction, which may partly explain the higher prevalence of COPD in China. Clinicians should be aware of this long-term risk in individuals with prior TB, irrespective of smoking status, particularly in patients from countries with a high TB burden.

The effect of smoking on the male excess of bladder cancer: a meta-analysis and geographical analyses.

Smoking is considered the primary risk factor for bladder cancer. Although smoking prevalence and bladder cancer incidence vary around the world, bladder cancer is on average 4 times more common in males than in females. This article describes the observed male–female incidence ratio of bladder cancer for 21 world regions in 2002 and 11 geographical areas during the time period 1970–1997. A meta‐analysis, including 34 studies, was performed to ascertain the increased risk for bladder cancer in males and females when smoking. The summary odds ratios (SORs) calculated in the meta‐analysis were used to estimate the male–female incidence ratio of bladder cancer that would be expected for hypothetical smoking prevalence scenarios. These expected male–female incidence ratios were compared with the observed ratios to evaluate the role of smoking on the male excess of bladder cancer. The male–female incidence ratio of bladder cancer was higher than expected worldwide and over time, based on a smoking prevalence of 75% in males, 10% in females and an increased risk (SOR) of bladder cancer associated with smoking of 4.23 for males and 1.35 for females, respectively. This implied that, at least in the Western world, smoking can only partially explain the difference in bladder cancer incidence. Consequently, other factors are responsible for the difference in bladder cancer incidence.

Self-Reported Long Total Sleep Duration Is Associated With Metabolic Syndrome The Guangzhou Biobank Cohort Study

OBJECTIVE To examine the association between total sleep duration and the prevalence of metabolic syndrome (MetSyn) in older Chinese. RESEARCH DESIGN AND METHODS Cross-sectional analysis of baseline data from the Guangzhou Biobank Cohort Study (GBCS) was performed. Participants (n = 29,333) were aged ≥50 years. Risk of MetSyn and its components were identified for self-reported total sleep duration. RESULTS Participants reporting long (≥9 h) and short (<6 h) total sleep duration had increased odds ratio (OR) of 1.18 (95% CI 1.07–1.30) and 1.14 (1.05–1.24) for the presence of MetSyn, respectively. The relationship remained in long sleepers (OR 1.21 [1.10–1.34]) but diminished in short sleepers (0.97 [0.88–1.06]) after full adjustment. CONCLUSIONS Long sleep duration was associated with greater risk of MetSyn in older Chinese. Confirmation through longitudinal studies is needed. The mechanisms mediating the link between long sleep duration and MetSyn require further investigation.

Original ResearchCOPDPrior TB, Smoking, and Airflow Obstruction: A Cross-Sectional Analysis of the Guangzhou Biobank Cohort Study

BACKGROUND Prior pulmonary TB has been shown to be associated with a higher risk of airflow obstruction, which is the hallmark of COPD, but whether smoking modifies this relationship is unclear. We investigated the relationships between prior TB, smoking, and airflow obstruction in a Chinese population sample. METHODS Participants in the Guangzhou Biobank Cohort Study underwent spirometry, chest radiography, and a structured interview on lifestyle and exposures. Prior TB was defined as the presence of radiologic evidence suggestive of inactive TB. Airflow obstruction was based on spirometric criteria. RESULTS The prevalence of prior TB in this sample (N = 8,066, mean age: 61.9 years) was 24.2%. After controlling for sex, age, and smoking exposure, prior TB remained independently associated with an increased risk of airflow obstruction (odds ratio = 1.37; 95% CI, 1.13-1.67). Further adjustment for exposure to passive smoking, biomass fuel, and dust did not alter the relationship. Smoking did not modify the relationship between prior TB and airflow obstruction. CONCLUSIONS Prior TB is an independent risk factor for airflow obstruction, which may partly explain the higher prevalence of COPD in China. Clinicians should be aware of this long-term risk in individuals with prior TB, irrespective of smoking status, particularly in patients from countries with a high TB burden.