Effects of beta-carotene supplements on cancer prevention: meta-analysis of randomized controlled trials.

This meta-analysis aimed to investigate the effects of beta-carotene supplements alone on cancer prevention as reported by randomized controlled trials (RCTs). We searched PubMed, EMBASE, and CENTRAL. Among the 848 articles searched, 6 randomized controlled trials, including 40,544 total participants, 20,290 in beta-carotene supplement groups, and 20,254 in placebo groups, were included in the final analysis. In a meta-analysis of 6 RCTs, beta-carotene supplements had no preventive effect on either cancer incidence [relative risk (RR) = 1.08, 95% confidence interval (CI) = 0.99-1.18] or cancer mortality (RR = 1.00, 95% CI = 0.87-1.15). Similar findings were observed in both primary prevention trials and secondary prevention trials. Subgroup analyses by various factors revealed no preventive effect of beta-carotene supplementation on cancer prevention and that it significantly increased the risk of urothelial cancer, especially bladder cancer (RR = 1.52, 95% CI = 1.03-2.24) and marginally increased the risk of cancer among current smokers (RR = 1.07, 95% CI = 0.99-1.17). The current meta-analysis of RCTs indicated that there is no clinical evidence to support the overall primary or secondary preventive effect of beta-carotene supplements on cancer. The potential effects, either beneficial or harmful, of beta-carotene supplementation on cancer should not be overemphasized.

Effects of selenium supplements on cancer prevention: meta-analysis of randomized controlled trials.

This meta-analysis aimed to investigate the preventive effect of selenium supplements alone on cancer as reported by randomized controlled trials (RCTs). We searched PubMed, EMBASE, and the Cochrane Library in July 2009. Of the 461 articles searched, 8 articles on 9 RCTs, which included 152,538 total participants, 32,110 in antioxidant supplement groups, and 120,428 in placebo groups, were included. In a random-effects meta-analysis of all 9 RCTs, selenium supplementation alone was found to have an overall preventive effect on cancer incidence [relative risk (RR) = 0.76; 95% confidence interval (CI) = 0.58-0.99]. Among subgroup meta-analyses, the preventive effect of selenium supplementation alone on cancer was apparently observed in populations with a low baseline serum selenium level (<125.6 ng/mL) (RR = 0.64; 95% CI = 0.53 to 0.78; I(2) = 45.5%; n = 7) and in high-risk populations for cancer (RR = 0.68; 95% CI = 0.58 to 0.80; I(2) = 41.5%; n = 8). The meta-analysis of randomized controlled trials indicates that there is possible evidence to support the use of selenium supplements alone for cancer prevention in the low baseline serum selenium level population and in the high-risk population for cancer.

Effects of vitamin treatment or supplements with purported antioxidant properties on skin cancer prevention: a meta-analysis of randomized controlled trials.

AIMS: To investigate the effect of vitamin treatment or supplements with purported antioxidant properties on the primary and secondary prevention of skin cancer using a meta-analysis of randomized controlled trials (RCTs). METHODS: We searched PubMed, Embase and the Cochrane Library in June 2009. Among 398 articles searched, 11 articles on 10 RCTs were included in the final analysis. RESULTS: In a fixed-effects meta-analysis of all 10 trials, vitamin treatment or supplements with purported antioxidant properties were found to have no preventive effect on skin cancer [relative risk (RR) = 0.98; 95% confidence interval (CI) = 0.94-1.03]. Similar findings were observed in a subgroup meta-analysis of 10 studies on both primary prevention trials (RR = 0.98; 95% CI = 0.93-1.03) and secondary prevention trials (RR = 0.97; 95% CI = 0.83-1.13). Further, subgroup meta-analyses revealed no preventive effect on cancer by type of antioxidant, type of cancer and the methodological quality of the studies. CONCLUSION: The current meta-analysis of RCTs indicated that there is no clinical evidence to support an overall primary and secondary preventive effect of vitamin treatment or supplements with purported antioxidant properties on skin cancer. The effect of vitamin supplements on skin cancer should not be overemphasized.

Effectiveness of pharmacologic therapy for smoking cessation in adolescent smokers: Meta-analysis of randomized controlled trials.

PURPOSE: The effectiveness of pharmacologic therapy for smoking cessation in adolescent smokers was evaluated. METHODS: In this meta-analysis, the medical literature was searched for randomized controlled trials (RCTs) investigating the effect of pharmacologic therapy for smoking cessation in smokers age 20 years or younger. The overall effect of pharmacologic therapy was based on the longest follow-up data available in each study. The effects of pharmacologic therapy by follow-up period, type of pharmacologic therapy, and type of strategy analysis were also compared among RCTs. Secondary outcome measures were adverse events reported from each study. RESULTS: Six RCTs involving 816 smokers age 12-20 years were included in the final analysis. No significant increase in abstinence rates was detected with pharmacologic therapy (relative risk [RR], 1.38; 95% confidence interval [CI], 0.92-2.07; I(2) = 0.0%) in a fixed-effects meta-analysis. Similarly, no significant increase in abstinence rates was found in subgroup meta-analyses of studies with both short-term (≤ 12 weeks) (RR, 1.23; 95% CI, 0.92-1.65) and mid-term (26 weeks) follow-up periods (RR, 1.60; 95% CI, 0.90-2.82). Although few serious adverse events were reported, there was no evidence directly linking these effects to the pharmacologic therapy used. CONCLUSION: A meta-analysis found that pharmacologic therapy for smoking cessation among adolescent smokers did not have a significant effect on abstinence rates at short-term and mid-term follow-up times of <26 weeks, and the RCTs examined found few adverse events. However, the results may have been affected by the limited number of participants in published trials.

Prediagnosis smoking, obesity, insulin resistance, and second primary cancer risk in male cancer survivors: National Health Insurance Corporation Study.

PURPOSE: Smoking, obesity, and insulin resistance are well-known risk factors for cancer, yet few epidemiology studies evaluate their role as risk factors for a second primary cancer (SPC). PATIENTS AND METHODS: We identified 14,181 men with a first cancer from the National Health Insurance Corporation Study cohort. We obtained data on fasting glucose level, body mass index (BMI), and smoking history from an enrollment interview (1996). We obtained SPC incidence data for 1996 through 2002 from the Korean Central Cancer Registry. We used the standard Poisson regression model to estimate the age- and multivariate-adjusted relative risk (RR) for SPCs in relation to smoking history, BMI, and insulin resistance before diagnosis. RESULTS: We observed 204 patients with SPC. The overall age-standardized incidence rate of SPC was 603.2 occurrences per 100,000 person-years, which was about 2.3 times higher than that of first cancer in the general male population. Multivariate regression revealed that lung (RR, 3.69; 95% CI, 1.35 to 10.09) and smoking-related (RR, 2.02; 95% CI, 1.02 to 4.03) SPCs were significantly associated with smoking. Obese patients (BMI > or = 25 kg/m2) had significantly elevated RRs for colorectal (RR, 3.45; 95% CI, 1.50 to 7.93) and genitourinary (RR, 3.61; 95% CI, 1.36 to 9.54) SPCs. Patients with a fasting serum glucose concentration > or = 126 mg/dL had a higher RR for hepatopancreatobiliary (RR, 3.33; 95% CI, 1.33 to 8.37) and smoking-related (1.93; 95% CI, 1.01 to 3.68) SPCs. CONCLUSION: Prediagnosis smoking history, obesity, and insulin resistance were risk factors for several SPCs. These findings suggest that more thorough surveillance and screening for SPCs is needed for the cancer survivors with these risk factors.

A retrospective cohort study on obesity and hypertension risk among Korean adults.

A retrospective cohort of adult Korean males and females was conducted to evaluate the influence of obesity on the development of hypertension and to determine the level of the body mass index at which the risk of hypertension significantly increases. The subjects of this study were 1,467 men and 944 women aged 20 to 75 yr who were normotensive at the time of their initial examinations from 1990 to 1991, who had a follow-up examination at least 1 yr after their initial examinations, or whose blood pressure status could be confirmed by reviewing their medical records until June 2000. During an average follow-up period of 6.2 yr, 234 new cases of hypertension were identified. An analysis using the Cox proportional hazards model showed that the risk of developing hypertension increased with increasing age, body mass index, and amount of daily alcohol consumption in men; and with increasing age and body mass index in women. Comparing men and women whose body mass indices were smaller than 23 kg/m(2), the relative risks of hyper-tension were 2.56 times greater in men and 3.17 times greater in women, whose body mass indices were greater than 27 kg/m(2). Our study confirmed that obesity is a strong risk factor for hypertension among Korean adults. In addition, high alcohol consumption may be a significant risk factor for men.

Nurses' willingness to maximize opioid analgesia for severe cancer pain, and its predictor.

GOALS OF WORK: The effectiveness of cancer pain management (CPM) is influenced by nurses' willingness to maximize opioid analgesia for severe cancer pain. The purposes of this study were to identify the willingness of nurses to provide maximum-dose opioids whenever needed for CPM and to determine its associated predictors. METHODS: This multicenter study was conducted among the entire total of registered nurses in seven large hospitals in Korea. Its overall response rate was 41.6%, and the data from 930 who responded (40.1%) were analyzed. We utilized a three-step, multidimensional, multiple logistic regression to identify the predictors of nurses' willingness. MAIN RESULTS: Only 255 nurses (27.4%) indicated that they recommended the maximum dose of opioids whenever it was needed. The respondents who were more likely to recommend morphine showed the following characteristics: older nurses (odds ratio, OR, 1.57; confidence interval, CI, 1.13-2.19); they knew the effectiveness of opioids for CPM (OR 1.53; CI 1.06-2.20); rarely concerned about a patient's addiction to opioids (OR 2.16; CI 1.48-3.15), or to a family member's addiction (OR 1.81; CI 1.20-2.73); prior experience with pain assessment tools (OR 1.62; CI 1.11-2.37); practical experience caring for cancer patients with pain over 51% (OR 1.55; CI 1.09-2.19). CONCLUSIONS: Our multicenter study suggested that in order to improve nurses' willingness to recommend opioids liberally in CPM: (1) attitudes about fear of opioid addiction must be changed; (2) the efficiency of opioids in CPM must be taught; and (3) implementation of pain assessment tools must be undertaken.

Cut-off point of BMI and obesity-related comorbidities and mortality in middle-aged Koreans.

OBJECTIVE: The need for a lower BMI to classify overweight in Asian populations has been controversial. Using both disease and mortality outcomes, we investigated whether lower BMI cut-off points are appropriate for identifying increased health risk in Koreans. RESEARCH METHODS AND PROCEDURES: We conducted a cohort study among 773,915 men and women from 30 to 59 years old with 8- to 10-year follow-up periods. Primary outcomes were change of obesity prevalence, obesity-related disease incidence, and all-cause mortality. RESULTS: Prevalence of overweight (BMI of 25.0-29.9) has steadily increased (1.3% annually), whereas obesity (BMI > or = 30) showed a lower prevalence and only a slight increase (0.1%-0.2% annually). Our study revealed that dose-response relationships exist between obesity and related disease incidences (hypertension, type 2 diabetes, and hypercholesterolemia) beginning at lower BMI levels than previously reported. Compared with those in the healthy weight range, Koreans with a BMI > or = 25 were not at greater risk of hypertension, type 2 diabetes, or hypercholesterolemia than has been reported for whites in similar studies. Obesity-related all-cause mortality also did not seem so different from that of whites. DISCUSSION: Our findings did not support the use of a lower BMI cut-off point for defining overweight in Koreans compared with whites for the purpose of identifying different risks. However, populations with BMI > or = 25 are rapidly increasing and have substantial risks of diseases. To preempt the rapid increases in obesity and related health problems that are occurring in Western countries, Korea should consider using a BMI of 25 as an action point for obesity prevention and control interventions.

Multicenter study of pain and its management in patients with advanced cancer in Korea.

The aim of this study was to evaluate the prevalence, severity, and management of pain in Korean patients with advanced cancer, and to identify the predictors of inadequate management of cancer pain in Korea. From 8 university hospitals, 655 patients with advanced cancer were surveyed. Information concerning analgesics prescribed was acquired from the medical records by the investigator. Physicians, nurses and caregivers were asked to estimate patients' pain. The Korean Brief Pain Inventory and the Barrier Questionnaire were completed by the patients. The Pain Management Index was estimated. Among all patients, 70.8% (464 of 655) reported pain. Among those who had pain, 63.6% (295 of 464) reported pain rated 5 or higher on a 0-10 scale. Thirty-nine percent of the patients had not received any analgesics and 53.2% were not receiving optimal pain management. Although there was a correlation between patients' pain ratings and those of doctors, nurses, and caregivers, there was no significant correlation between patients' ratings and health care providers' ratings at pain levels above moderate intensity. Cancer pain was more poorly managed in advanced cancer than terminal cancer patients (OR:3.20, 95%C.I, 1.83-5.60), in patients with better performance(OR:3.17, 95%C.I, 1.64-6.11), and in those patients whose pain was underestimated by the doctor (OR:2.58, 95%C.I. 1.42-4.69). Despite the high prevalence and severity of pain in cancer patients, the assessment and management of cancer pain were found to be inadequate in Korea.

Determinants of non-compliance with lipid-lowering therapy in hyperlipidemic patients.

PURPOSE: In order to assess the determinants of non-compliance with a lipid-lowering therapy, a prospective study of the hyperlipidemic Korean subjects was carried out. METHODS: A total of 1019 patients was observed by 46 family physicians for the period of 1 year from January 1999 to January 2000. To ascertain the compliance associated with a lipid lowering drug (Simvastatin), we regularly followed up the hyperlipidemic patients at intervals of 4, 12 and 24 weeks. The criterion for evaluating compliance is to measure clinic attendance. Using a structured questionnaire, patients and physicians were asked about risk factors for the compliance. RESULTS: During the first 24 weeks of treatment, the lipid-lowering medication was continued by 52.3% and discontinued by 19.7%. The remaining 28% dropped out. Patient-related factors for non-compliance were young age, current smoker, lack of low fat diet and exercise, new user, no concomitant medication, and occurrence of adverse reactions. Physician-related factors for non-compliance were low patients' satisfaction with the physician, small number of hyperlipidemic patients per month and working in a relatively small hospital. CONCLUSIONS: Compliance with the lipid-lowering therapy was relatively low and several factors for non-compliance were detected.