Dietary Intake of Omega-3 fatty acids and Endocrine-related Gynecological Cancer: A Meta-Analysis of Observational Studies / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Previous observational epidemiological studies have reported inconsistent findings on the association between dietary intake of omega-3 fatty acids and endocrine-related gynecological cancer such as ovarian cancer and endometrial cancer. This study aimed to investigate this association using a meta-analysis of observational studies. MATERIALS AND METHODS: We searched PubMed, EMBASE, and Cochrane library by using key words related with the topic in April 2017. The pooled odd ratios (pORs), relative risks (pRRs), or hazard ratios (pHRs) with 95% confidence intervals (CIs) were calculated based on the random-effects model. Also, we performed subgroup meta-analysis by methodological quality, types of cancer, study design, and omega-3 fatty acids. RESULTS: A total of ten observational studies with six case-control and four cohort studies were included in the final meta-analysis. In the meta-analysis of all the studies, dietary intake of total omega-3 fatty acids was not significantly associated with the risk of endometrial and ovarian cancers (pOR/HR, 0.87; 95% CI, 0.73-1.04; I²=67.2%) (highest versus lowest intake). In the subgroup meta-analysis by type of study, there was no significant association between them in cohort studies (pHR, 1.03; 95% CI, 0.63-1.67, I²=81.9%), whereas its reduced risk was observed in case-control studies (pOR, 0.81; 95% CI, 0.67 to 0.98, I²=55.7%). CONCLUSION: The current meta-analysis of observational studies suggests that there is no higher level of evidence to support the protective effect of dietary omega-3 fatty acids on endocrine-related gynecological cancer. Further prospective studies should be conducted to confirm the association.

Light Alcohol Drinking and Risk of Cancer: A Meta-Analysis of Cohort Studies / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: The purpose of this study was to determine whether light alcohol drinking increases the risk of cancer by using a meta-analysis of cohort studies because the newly revised 2015 European Code against Cancer fourth edition on alcohol and cancer was based on critical flaws in the interpretation and citation of the previous meta-analyses. MATERIALS AND METHODS: PubMed and EMBASE were searched in April, 2016. Two authors independently reviewed and selected cohort studies on the association between very light (≤ 0.5 drink/day), light (≤ 1 drink/day), or moderate drinking (1-2 drinks/day) and the risk of cancer incidence and mortality. A pooled relative riskwith its 95% confidence intervalwas calculated by a random-effects meta-analysis. Main outcome measures were cancer incidence and mortality. RESULTS: A total of 60 cohort studies from 135 articles were included in the final analysis. Very light drinking or light drinking was not associated with the incidence of most cancers except for female breast cancer in women and male colorectal cancer. Conversely, light drinking was associated with a decreased incidence of both female and male lung cancer significantly and both female and male thyroid cancer marginally significantly. Moderate drinking significantly increased the incidence of male colorectal cancer and female breast cancer,whereas it decreased the incidence of both female and male hematologic malignancy. CONCLUSION: We found that very light or light alcohol drinking was not associated with the risk of most of the common cancers except for the mild increase in the incidence of breast cancer in women and colorectal cancer in men.

Night Shift Work and Risk of Depression: Meta-analysis of Observational Studies

This study aimed to assess whether night shift work is associated with the risk of depression by using a meta-analysis of observational studies. We searched PubMed and EMBASE in August, 2016 to locate eligible studies and investigated the association between night shift work and the risk of depression, reporting outcome measures with adjusted odds ratios (ORs) or relative risks (RRs) and 95% confidence intervals (CIs). In the meta-analysis of a total of 11 observational studies with 9 cross-sectional study, 1 longitudinal study, and 1 cohort study, night shift work was significantly associated with an increased risk of depression (OR/RR, 1.43; 95% CI, 1.24–1.64; I² = 78.0%). Also, subgroup meta-analyses by gender, night shift work duration, type of occupation, continent, and type of publication showed that night shift work was consistently associated with the increased risk of depression. The current meta-analysis suggests that night shift work is associated with the increased risk of depression. However, further large prospective cohort studies are needed to confirm this association.

The Law for Health Functional Foods, It is Time to Repeal / 임상당뇨병

According to a 2017 report from the Ministry of Food and Drug Safety of Korea (MFDS), the production quantity of health functional foods has increased by 29.9% from 1.133 trillion won in 2015 to 1.472 trillion won in 2016. Also, many people believe that such foods are beneficial for our health, and industries are advertising them and promoting sales under approval from the MFDS. However, the health functional foods system in Korea has important problems and flaws in terms of the definition and functional grading of health functional foods. Further, when thoroughly reviewed based on the recent literature, there is insufficient evidence to support the use of health functional foods. Therefore, it is time to repeal the Law for Health Functional Foods.

Alcohol Intake and Risk of Thyroid Cancer: A Meta-Analysis of Observational Studies / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: The purpose of this study was to assess whether alcohol intake is associated with the risk of thyroid cancer by a meta-analysis of observational studies. MATERIALS AND METHODS: We searched PubMed and EMBASE in June of 2015 to locate eligible studies. We included observational studies such as cross-sectional studies, case-control studies, and cohort studies reporting odd ratios (ORs) or relative risk (RRs) with 95% confidence intervals (CIs). RESULTS: We included 33 observational studies with two cross-sectional studies, 20 case-controls studies, and 11 cohort studies, which involved a total of 7,725 thyroid cancer patients and 3,113,679 participants without thyroid cancer in the final analysis. In the fixed-effect model meta-analysis of all 33 studies, we found that alcohol intake was consistently associated with a decreased risk of thyroid cancer (OR or RR, 0.74; 95% CI, 0.67 to 0.83; I2=38.6%). In the subgroup meta-analysis by type of study, alcohol intake also decreased the risk of thyroid cancer in both case-control studies (OR, 0.77; 95% CI, 0.65 to 0.92; I2=29.5%; n=20) and cohort studies (RR, 0.70; 95% CI, 0.60 to 0.82; I2=0%; n=11). Moreover, subgroup meta-analyses by type of thyroid cancer, gender, amount of alcohol consumed, and methodological quality of study showed that alcohol intake was significantly associated with a decreased risk of thyroid cancer. CONCLUSION: The current meta-analysis of observational studies found that, unlike most of other types of cancer, alcohol intake decreased the risk of thyroid cancer.

Risk Factors for Thyroid Cancer: A Hospital-Based Case-Control Study in Korean Adults / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Although the incidence of thyroid cancer in Korea has rapidly increased over the past decade, few studies have investigated its risk factors. This study examined the risk factors for thyroid cancer in Korean adults. MATERIALS AND METHODS: The study design was a hospital-based case-control study. Between August 2002 and December 2011, a total of 802 thyroid cancer cases out of 34,211 patients screened from the Cancer Screenee. Cohort of the National Cancer Center in South Korea were included in the analysis. A total of 802 control cases were selected from the same cohort, and matched individually (1:1) by age (±2 years) and area of residence for control group 1 and additionally by sex for control group 2. RESULTS: Multivariate conditional logistic regression analysis using the control group 1 showed that females and those with a family history of thyroid cancer had an increased risk of thyroid cancer, whereas ever-smokers and those with a higher monthly household income had a decreased risk of thyroid cancer. On the other hand, the analysis using control group 2 showed that a family history of cancer and alcohol consumption were associated with a decreased risk of thyroid cancer, whereas higher body mass index (BMI) and family history of thyroid cancer were associated with an increased risk of thyroid cancer. CONCLUSION: These findings suggest that females, those with a family history of thyroid cancer, those with a higher BMI, non-smokers, non-drinkers, and those with a lower monthly household income have an increased risk of developing thyroid cancer.

Effects of Vitamin and Antioxidant Supplements in Prevention of Bladder Cancer: a Meta-Analysis of Randomized Controlled Trials

This study aimed to investigate the effects of vitamin and antioxidant supplements in the prevention of bladder cancer using a meta-analysis of randomized controlled trials (RCTs). Fourteen RCTs were included in the final analysis. In a fixed-effect meta-analysis, vitamin and antioxidant supplements showed no preventive effect for bladder cancer (relative risk [RR] = 1.04; 95% confidence interval [CI] 0.92–1.17; I² = 39.7%). Also, there was no preventive effect of these supplements in the subgroup meta-analyses by various factors such as type of supplements, type of cancer prevention, methodological quality, providers of supplements, type of control group, and number of participants. Among the subgroup analyses by type of supplements, beta-carotene supplementation alone marginally increased the risk of bladder cancer (RR = 1.44; 95% CI 1.00–2.09; I² = 0.0%; n = 3). The current meta-analysis found that vitamin and antioxidant supplements have no preventive effect against bladder cancer.

Efficacy of Ginseng Supplements on Fatigue and Physical Performance: a Meta-analysis

We conducted a meta-analysis to investigate the efficacy of ginseng supplements on fatigue reduction and physical performance enhancement as reported by randomized controlled trials (RCTs). RCTs that investigated the efficacy of ginseng supplements on fatigue reduction and physical performance enhancement compared with placebos were included. The main outcome measures were fatigue reduction and physical performance enhancement. Out of 155 articles meeting initial criteria, 12 RCTs involving 630 participants (311 participants in the intervention group and 319 participants in the placebo group) were included in the final analysis. In the fixed-effect meta-analysis of four RCTs, there was a statistically significant efficacy of ginseng supplements on fatigue reduction (standardized mean difference, SMD = 0.34; 95% confidence interval [CI] = 0.16 to 0.52). However, ginseng supplements were not associated with physical performance enhancement in the fixed-effect meta-analysis of eight RCTs (SMD = −0.01; 95% CI = −0.29 to 0.27). We found that there was insufficient clinical evidence to support the use of ginseng supplements on reducing fatigue and enhancing physical performance because only few RCTs with a small sample size have been published so far. Further lager RCTs are required to confirm the efficacy of ginseng supplements on fatigue reduction.

Smartphones and health

The use of smartphones has rapidly increased over the past few years. With the increasing use of smartphones, concern has been raised about the potential harmful effects on human health. In 2011, the International Agency for Research on Cancer of the World Health Organization classified radiofrequency electromagnetic fields as possibly carcinogenic to humans (group 2B) based on an increased risk for glioma associated with wireless phone use (i.e. mobile phones). In addition, several meta-analyses of case-control studies reported an increased risk of tumors associated with the use of mobile phones. Moreover, it has been reported that the overuse of mobile phones is associated with reproductive risks, addiction, and phantom vibration and ringing syndrome. Further large prospective cohort studies and randomized controlled trials are needed to confirm these associations. Until clear evidence is available that the use of smartphones is safe, their overuse should be avoided.

Efficacy of Vitamin C Supplements in Prevention of Cancer: A Meta-Analysis of Randomized Controlled Trials / 가정의학회지

BACKGROUND: Previous randomized controlled trials (RCTs) have reported inconsistent findings regarding the association between vitamin C supplementation and the risk of cancer. METHODS: We performed a meta-analysis of RCTs to investigate the efficacy of vitamin C supplements for prevention of cancer. We searched the PubMed, EMBASE, and Cochrane Library databases in November 2014 using common keywords related to vitamin C supplements and cancer. RESULTS: Among 785 articles, a total of seven trials were identified, which included 62,619 participants; 31,326 and 31,293 were randomized to vitamin C supplementation and control or placebo groups, respectively, which were included in the final analysis. A fixed-effects meta-analysis of all seven RCTs revealed no significant association between vitamin C supplementation and cancer (relative risk, 1.00; 95% confidence intervals, 0.95-1.05). Similarly, subgroup meta-analysis by dose of vitamin C administered singly or in combination with other supplements, follow-up period, methodological quality, cancer mortality, gender, smoking status, country, and type of cancer also showed no efficacy of vitamin C supplementation for cancer prevention. CONCLUSION: This meta-analysis shows that there is no evidence to support the use of vitamin C supplements for prevention of cancer.

Jumping up to the Next Step toward the World's Leading Journal in Primary Care Medicine / 가정의학회지

No abstract available.

Use of Proton Pump Inhibitor and Risk of Colorectal Cancer: A Meta-analysis of Observational Studies / 가정의학회지

BACKGROUND: Previous case-control studies have reported inconsistent findings regarding the association between proton pump inhibitor (PPI) use and colorectal cancer (CRC) risk. We investigated these associations using meta-analysis. METHODS: We searched MEDLINE (PubMed), EMBASE, and the Cochrane Library in April 2011. Two evaluators independently reviewed and selected articles, based on pre-determined selection criteria. RESULTS: Out of 737 articles meeting our initial criteria, 5 case-control studies, which involved 120,091 participants (9,514 cases and 110,577 controls), were included in the final analyses. The overall use of PPI (used vs. never or rarely used) was not significantly associated with the risk of CRC in a fixed-effects model meta-analysis of all 5 case-control studies (odds ratio [OR], 1.08; 95% confidence interval [CI], 0.96 to 1.20; I2 = 3.5%). Also, in sensitivity meta-analysis by cumulative duration of PPI use, there was no association between PPI use of 1 year or longer and the risk of colorectal cancer in a fixed-effects meta-analysis (OR, 1.09; 95% CI, 0.98 to 1.22; I2 = 0%). CONCLUSION: Although hypergastrinemia could be an important factor in the pathogenesis of some colorectal cancers, our study suggests that this does not lead to significant clinical risk for most PPI users. Further prospective studies or randomized controlled trials related to PPI use and colorectal cancer risk are needed to investigate this association.

Relationships between Household Smoking Restrictions and Intention to Quit Smoking among Korean American Male Smokers in California

This cross-sectional study examined the relationships between household smoking restrictions and intentions to quit smoking among Korean American male smokers in California. We used data from the California Korean American Tobacco Use Survey (CKATUS), which was conducted in 2004 using computer-assisted telephone interviewing. Among the 2,545 respondents who participated in the CKATUS, the 387 male smokers who answered a question assessing their intention to quit smoking were included in the final analyses. In univariable analyses, smokers who reported having household smoking restrictions were more likely to intend to quit smoking as compared with those who did not (P<0.01). Other independent correlates of having an intention to quit smoking were being less than 50 yr of age, having spent more than 50% of one's life in the US, being assimilated, and having other smokers in the household. In a multiple logistic regression analysis, the significant correlates of having an intention to quit smoking were household smoking restrictions (complete or partial restriction vs. no restriction on smoking; odds ratio, 2.54; 95% confidence interval, 1.22-5.28) and absence of other smokers in the household. In conclusion, smoking restrictions in the household are associated with an intention to quit smoking among Korean American male smokers in California.

Erratum: Correction of References

No abstract available.

Self-Reported Exposure to Second-Hand Smoke and Positive Urinary Cotinine in Pregnant Nonsmokers

PURPOSE: This cross-sectional study aimed to examine the association between self-reported exposure status to second-hand smoke and urinary cotinine level in pregnant nonsmokers. MATERIALS AND METHODS: We recruited pregnant nonsmokers from the prenatal care clinics of a university hospital and two community health centers, and their urinary cotinine concentrations were measured. RESULTS: Among a total of 412 pregnant nonsmokers, the proportions of self-reported exposure to second-hand smoke and positive urinary cotinine level were 60.4% and 3.4%, respectively. Among those, 4.8% of the participants who reported exposure to second-hand smoke had cotinine levels of 40 ng/mL (the kappa value = 0.029, p = 0.049). Among those who reported living with smokers (n = 170), "smoking currently permitted in the whole house" (vs. not permitted at home) was associated with positive urinary cotinine in the univariable analysis. Furthermore, this variable showed a significant association with positive urinary cotinine in the stepwise multiple logistic regression analysis [Odds ratio (OR), 15.6; 95% Confidence interval (CI) = 2.1-115.4]. CONCLUSION: In the current study, the association between self-reported exposure status to second-hand smoke and positive urinary cotinine in pregnant nonsmokers was poor. "Smoking currently permitted in the whole house" was a significant factor of positive urinary cotinine in pregnant nonsmokers. Furthermore, we suggest that a complete smoking ban at home should be considered to avoid potential adverse effects on pregnancy outcomes due to second-hand smoke.

Effectiveness of Proactive Quitline Service and Predictors of Successful Smoking Cessation: Findings from a Preliminary Study of Quitline Service for Smoking Cessation in Korea

This study was to evaluate the effectiveness of the first proactive Quitline service for smoking cessation in Korea and determine the predictors of successful smoking cessation. Smoking participants were voluntarily recruited from 18 community health centers. The participants were proactively counseled for smoking cessation via 7 sessions conducted for 30 days from November 1, 2005 to January 31, 2006. Of the 649 smoking participants, 522 completed 30 days at the end of the study and were included in the final analysis. The continuous abstinence rate at 30 days of follow-up was found to be 38.3% (200/522), in the intention-to-treat analysis. Compared with non-quitters, quitters were mostly male, smoked or =20 yr, and were less dependent on nicotine. Based on the stepwise multiple logistic regression analysis, the significant predictors of successful smoking cessation were determined to be male sex, low cigarette consumption, and older age at smoking initiation. We investigated the short-term effectiveness of the Quitline service and determined the predictors of successful smoking cessation.

Smoking-related Characteristics in Korean Adult Smokers: Findings from the 2005 International Tobacco Control Policy Evaluation Survey-Korea

BACKGROUND: This study reports findings from the ITC Korea Survey, which was conducted to evaluate the characteristics in Korean adult smokers as part of the ITC Project. METHODS: Adult male and female smokers were randomly selected using telephone survey from November to December 2005. The ITC Korea Survey contained a wide range of questions on smoking behavior and smoking history. The data reported are weighted on the basis of age and gender, and they are nationally representative of smokers in Korea. RESULTS: A total of 1,002 smokers among the selected 1,402 subjects (71.5%) were interviewed; 96.2% were males. Daily smokers comprised 94.5% of the sample. The mean of cigarettes per day was 17.9. The average minutes after waking before the first cigarette was smoked was lower (50.6 minutes) than it was in other countries of the ITC Project. Over 90% considered themselves addicted to cigarettes and 86.5% expressed regret over smoking. Smokers reported that the norms against smoking in Korea were very strong both personal norms (89.4%) and perceived norms in Korean society (86.3%). Among the smokers, 80.8% had tried to quit smoking, and 76.1% were planning to quit. Only 5.8% of the Korean smokers indicated that the warning labels made them a lot more likely to quit smoking. When the price of cigarettes increased by 500 won (25%) in December 2004, 34.3% reported trying to quit smoking. Only 17.7% supported a complete workplace ban and 15.8% supported a complete ban in restaurants. Although knowledge of the harms of smoking was high, nearly 80% of the Koreans wrongly believed that "nicotine causes most of the cancer in smokers." Finally, the great majority (85.2%) of smokers in Korea believed that "the government should do more to tackle the harm done by smoking" and 62.5% believed that "tobacco products should be more tightly regulated." CONCLUSION: The results from the baseline wave of the ITC Korea Survey have identified where tobacco control in Korea has been done. Future waves of the ITC Korea Survey will be able to evaluate the impact of important tobacco control policies that Korea will be required to implement over the next few years, as a party to the FCTC.

Sociodemographic and Smoking Behavioral Predictors Associated with Smoking Cessation According to Follow-up Periods: A Randomized, Double-blind, Placebo-controlled Trial of Transdermal Nicotine Patches

This study investigated sociodemographic and smoking behavioral factors associated with smoking cessation according to follow-up periods. In this randomized, double-blind, placebo-controlled trial of transdermal nicotine patches, subjects were a total of 118 adult male smokers, who were followed up for 12 months. Univariable logistic regression analysis and stepwise multiple logistic regression analyses were performed to identify the predictors of smoking cessation. The overall self-reported point prevalence rates of abstinence were 20% (24/118) at 12 months follow-up, and there was no significant difference in abstinence rates between placebo and nicotine patch groups. In the univariable logistic regression analysis, predictors of successful smoking cessation were the low consumption of cigarettes per day and the low Fagerstrom Test for Nicotine Dependence (FTND) scores (p<0.05) at 3, 6, and 12 months follow-up. In the stepwise multiple logistic regression analyses, predictors of successful smoking cessation, which were different according to the follow- up periods, were found to be the low consumption of cigarettes per day at the short-term and midterm follow-up (< or =6 months), older age, and the low consumption of cigarettes per day at the long-term follow-up (12 months).

GSTM1 and GSTP1 Polymorphisms as Potential Factors for Modifying the Effect of Smoking on Inflammatory Response

Inflammation has been known to be an important underlying condition for development of various diseases including cancer. The aims of this study were to investigate whether tobacco smoke exposure increases the level of inflammation biomarkers and the GSTM1 and GSTP1 gene polymorphisms are associated with inflam matory response due to tobacco smoke exposure. We measured urinary cotinine level in 300 healthy university students. Total serum TNF-alpha levels and blood WBC counts were determined to evaluate inflammatory response. Allelic loss of the GSTM1 and the GSTP1 (Ile105Val) polymorphism were determined by PCR and RFLP. Tobacco smoke exposure was found to be associated with increase of both TNF-alpha level and WBC count. Particularly, smokers with combination of GSTM1 null and GSTP1 AG or GG genotypes showed higher TNF-alpha level than those with the other genotype combinations (p=0.07). This result suggests that smoking may induce inflammation measured as TNF-alpha level or WBC count and combinations of the GSTM1 and GSTP1 polymorphisms may modify the effect of smoking on serum TNF-alpha level.

GSTM1 and GSTP1 Polymorphisms as Potential Factors for Modifying the Effect of Smoking on Inflammatory Response

Inflammation has been known to be an important underlying condition for development of various diseases including cancer. The aims of this study were to investigate whether tobacco smoke exposure increases the level of inflammation biomarkers and the GSTM1 and GSTP1 gene polymorphisms are associated with inflam matory response due to tobacco smoke exposure. We measured urinary cotinine level in 300 healthy university students. Total serum TNF-alpha levels and blood WBC counts were determined to evaluate inflammatory response. Allelic loss of the GSTM1 and the GSTP1 (Ile105Val) polymorphism were determined by PCR and RFLP. Tobacco smoke exposure was found to be associated with increase of both TNF-alpha level and WBC count. Particularly, smokers with combination of GSTM1 null and GSTP1 AG or GG genotypes showed higher TNF-alpha level than those with the other genotype combinations (p=0.07). This result suggests that smoking may induce inflammation measured as TNF-alpha level or WBC count and combinations of the GSTM1 and GSTP1 polymorphisms may modify the effect of smoking on serum TNF-alpha level.