Alcohol drinking and breast cancer risk: an evaluation based on a systematic review of epidemiologic evidence among the Japanese population

BACKGROUND: We reviewed epidemiological studies on alcohol drinking and breast cancer among the Japanese population. This report is one among a series of articles by our research group evaluating the existing evidence concerning the association between health-related lifestyles and cancer. METHODS: Original data were obtained from MEDLINE searches using PubMed or from searches of the Ichushi database, complemented with manual searches. Evaluation of associations was based on the strength of evidence and the magnitude of association, together with biological plausibility as previously evaluated by the International Agency for Research on Cancer. RESULTS: Three cohort studies and eight case-control studies were identified. There were inconsistent results regarding alcohol drinking and breast cancer risk among cohort studies. A significant positive association was observed in one, but another showed nonsignificant inverse association. Out of the eight case-control studies, two studies showed a significantly increased risk among women who drink daily and who had higher intake of alcohol, respectively. Experimental studies have supported the biological plausibility of a positive association between alcohol drinking and breast cancer risk. CONCLUSION: We conclude that epidemiologic evidence on the association between alcohol drinking and breast cancer risk remains insufficient in terms of both the number and methodological quality of studies among the Japanese population.     

Alcohol drinking and lung cancer risk: an evaluation based on a systematic review of epidemiologic evidence among the Japanese population

BACKGROUND: The relationship between alcohol consumption and risk of lung cancer is controversial. Based on a systematic review of epidemiologic evidence, we evaluated this association among the Japanese population, who may be more susceptible to alcohol-related diseases than Western populations. METHODS: Original data were obtained from MEDLINE searches using PubMed or from searches of the Ichushi database, complemented with manual searches. The evaluation of associations was based on the strength of evidence and the magnitude of association, together with biological plausibility as previously evaluated by the International Agency for Research on Cancer. RESULTS: We identified seven cohort studies and two case-control studies. One cohort study demonstrated a strong positive association between alcohol drinking and the risk of female lung cancer, but the association almost disappeared after adjustment for smoking. The other eight studies showed a weak positive or no association. Although smoking is the best-established risk factor for lung cancer, only five cohort studies presented smoking-adjusted risks out of all nine identified. Furthermore, only two studies explicitly reported the risk estimate for ex-drinkers who may have quit alcohol drinking after the development or diagnosis of the disease and have an apparently higher risk. CONCLUSION: We conclude that the epidemiologic evidence on the association between alcohol drinking and lung cancer risk remains insufficient in terms of both the number and methodological quality of studies among the Japanese population.     

Alcohol drinking and esophageal cancer risk: an evaluation based on a systematic review of epidemiologic evidence among the Japanese population

Although alcohol drinking is considered as an important risk factor for esophageal cancer, the magnitude of the association might be varied among geographic areas. Therefore, we reviewed epidemiologic studies on the association between alcohol drinking and esophageal cancer among the Japanese population. Original data were obtained from MEDLINE, searched using PubMed or from searches of the Ichushi database, complemented with manual searches. Evaluation of associations was based on the strength of evidence ('convincing', 'probable', 'possible' or 'insufficient') and the magnitude of association ('strong', 'moderate', 'weak' or 'no association'), together with biological plausibility as previously evaluated by the International Agency of Research on Cancer. We identified four cohort studies and nine case-control studies. All cohort studies and case-control studies showed strong positive associations between esophageal cancer and alcohol drinking. All cohort studies and six case-control studies showed that alcohol drinking had the dose- or frequency-response relationships with esophageal cancer. In addition, four case-control studies showed that acetaldehyde dehydrogenase Glu504Lys polymorphism had strong effect modification with alcohol drinking. We conclude that there is convincing evidence that alcohol drinking increases the risk of esophageal cancer in the Japanese population.     

Alcohol drinking and total cancer risk: an evaluation based on a systematic review of epidemiologic evidence among the Japanese population

BACKGROUND: We conducted a systematic review of epidemiological evidence to evaluate the association between alcohol drinking and total cancer risk among the Japanese population. METHODS: Original data were obtained from MEDLINE searches using PubMed or from searches of the Ichushi database, complemented with manual searches. Evaluation of associations was based on the strength of evidence and the magnitude of association, together with biological plausibility as previously evaluated by the International Agency of Research on Cancer. RESULTS: Of eight cohort studies identified, six studies, three of which included women, were subjected to evaluation. In men, all six studies showed a weak to moderate positive association between alcohol drinking and total cancer risk. While light drinking had little effect on total cancer risk, heavy drinking of more than 46-69 g of alcohol per day contributed to total cancer risk for most of these Japanese populations. However, no association was reported in women in any of the three studies. CONCLUSION: We conclude that there is convincing evidence that alcohol drinking increases the risk of total cancer in the Japanese population, specifically among heavy drinking men.     

Tobacco smoking and gastric cancer risk: an evaluation based on a systematic review of epidemiologic evidence among the Japanese population

BACKGROUND: We evaluated the association between tobacco smoking and gastric cancer risk among the Japanese population based on a systematic review of epidemiologic evidence. METHODS: Original data were collected by searches of MEDLINE using PubMed, complemented with manual searches. Evaluation of associations was based on the strength of evidence and the magnitude of association, together with biological plausibility, as evaluated previously by the International Agency for Research on Cancer. RESULTS: Ten cohort studies and 16 case-control studies were identified. In men, most studies reported moderate or strong positive associations between smoking and gastric cancer. In women, the positive association was weaker than in men. Of eight studies (three cohort studies and five case-case control studies), two cohort and three case control studies reported a weakly to strongly increased risk of gastric cancer. The summary relative risk for current smokers was estimated to be 1.56 (95% confidence intervals 1.36-1.80), 1.79 (1.51-2.12), 1.22 (1.07-1.38) for the total population, men and women, respectively. CONCLUSION: We conclude that there is convincing evidence that tobacco smoking moderately increases the risk of gastric cancer among the Japanese population.     

Alcohol drinking and colorectal cancer risk: an evaluation based on a systematic review of epidemiologic evidence among the Japanese population

BACKGROUND: It remains unclear whether alcohol drinking is causally associated with colorectal cancer. On the basis of a systematic review of epidemiological evidence, we evaluated this association among the Japanese population, who may be more susceptible to alcohol-related diseases than Western populations. METHODS: Original data were obtained from searches of MEDLINE using PubMed, complemented with manual searches. The evaluation of associations was based on the strength of evidence and the magnitude of association, together with biological plausibility as previously evaluated by the International Agency for Research on Cancer. RESULTS: We identified 5 cohort studies and 13 case-control studies. A moderate or strong positive association was observed between alcohol drinking and colon cancer risk in all large-scale cohort studies, with some showing a dose-response relation, and among several case-control studies. The risk of colon or colorectal cancer was increased even among moderate drinkers consuming <46 g of alcohol per day, levels at which no material increase in the risk was observed in a pooled analysis of Western studies. A positive association with rectal cancer was also reported, but it was less consistent, and the magnitude of the association was generally weaker compared with colon cancer. CONCLUSION: We conclude that alcohol drinking probably increases the risk of colorectal cancer among the Japanese population. More specifically, the association for the colon is probable, whereas that for the rectum is possible.     

Tobacco smoking and colorectal cancer risk: an evaluation based on a systematic review of epidemiologic evidence among the Japanese population

BACKGROUND: It is unclear whether tobacco smoking is related to colorectal cancer risk in Japan. We evaluated the association among the Japanese population based on a systematic review of epidemiologic evidence. METHODS: Original data were obtained from searches of MEDLINE using PubMed, complemented with manual searches. The evaluation of associations was based on the strength of evidence and the magnitude of association, together with biological plausibility as previously evaluated by the International Agency for Research on Cancer. RESULTS: A total of six cohort studies and 15 case-control studies were thus identified. A substantial degree of heterogeneity was observed in the association between smoking and colon cancer; most case-control studies published before 1994 reported an inverse association, whereas studies conducted over the last decade did not find any significant association. Recent cohort studies have shown a non-significant 20-40% increase in colon cancer risk associated with current smoking. Several recent case-control studies and some cohort studies have identified a weak to strong positive association between smoking and rectal cancer. CONCLUSION: We conclude that tobacco smoking possibly increases the risk of colorectal cancer among the Japanese population. More specifically, tobacco smoking may possibly increase the risk of rectal cancer; however, epidemiologic evidence is still insufficient to demonstrate any clear association with colon cancer.     

Cigarette smoking and liver cancer risk: an evaluation based on a systematic review of epidemiologic evidence among Japanese

BACKGROUND: Emerging epidemiologic data suggest that cigarette smoking may increase the risk of primary liver cancer. We evaluated this association based on a systematic review of epidemiologic evidence among Japanese populations. METHODS: Original data were obtained from MEDLINE searches using PubMed, complemented with manual searches. The evaluation was performed in terms of the magnitude of association ('strong', 'moderate', 'weak' or 'no association') in each study and the strength of evidence ('convincing', 'probable', 'possible' or 'insufficient'), together with biological plausibility as previously done by the International Agency for Research on Cancer. RESULTS: A total of 12 cohort studies and 11 case-control studies were identified. Nine cohort studies (two with adjustment for hepatitis B and C virus infections and seven without it) reported weak to strong positive associations between smoking and liver cancer, with dose-response relationships shown in three studies. Five case-controls studies (three with the virus adjustment and two without it) demonstrated such positive associations, with a dose-response relationship shown in only one study, while in six case-control studies, the observed associations were judged to be of the lowest magnitude or inverse due to the lack of any dose-response relationship. CONCLUSION: We conclude that cigarette smoking 'probably' increases the risk of primary liver cancer among the Japanese. Potential confounding by hepatitis virus infection and virus-smoking interactions need to be addressed in future studies.     

Evaluation based on systematic review of epidemiological evidence among Japanese populations: tobacco smoking and total cancer risk

BACKGROUND: We evaluated the association between tobacco smoking and total cancer risk among Japanese populations based on a systematic review of epidemiological evidence. METHODS: Original data were obtained from searches of MEDLINE using PubMed, complemented with manual searches. Evaluation of associations was based on the strength of evidence and the magnitude of association, together with biological plausibility as previously evaluated by the International Agency for Research on Cancer. Meta-analysis of associations was also conducted to obtain summary estimates of association. RESULTS: A total of eight cohort studies were identified. In men, all studies consistently showed a moderately increased risk of total cancer in current smokers compared with never-smokers. In women, an increase in risk was seen but was weaker than in men. The summary relative risk was estimated as 1.53 (95% confidence interval 1.41-1.65). CONCLUSION: We conclude that there is convincing evidence that current tobacco smoking moderately increases the risk ( approximately 1.5 times) of total cancer in the Japanese population compared with never-smoking Japanese.     

Alcohol Consumption and Risk of Esophageal Cancer in Japan: A Case-control Study in Seven Hospitals

In a multi-center case-control study, we evaluated the riskof esophageal cancer in the Japanese population. All patientsand controls were inpatients in the surgical departments ofseven hospitals nationwide. Patients eligible for the studywere those newly diagnosed as having primary esophageal cancer.One control per case was selected from among patients admittedto the same hospital, and 141 male pairs were analyzed usinglogistic regression analysis. The results showed dose-responserelation between the risk of esophageal cancer and both thequantity (g/week) and frequency (times/week) of alcohol drinking(P value for trend = 0.0001). Altough a statistically significantrisk increase was shown among moderate to heavy smokers (15 cigarette/day < 25) (odds ratio, 4.35:95% confidence interval,1.81-10.49), the dose-response for cigarette smoking was unclear(P value for trend = 0.07). No combined effect of alcohol drinkingand cigarette smoking was found. A frequent intake of fruitwas-associated with a decreased risk (P value for trend = 0.02).After adjustment for alcohol consumption, cigarette smokingand fruit intake were found not to be associated with the risk,whereas a preference for high-temperature food and drink showeda statistically significant positive association (P value fortrend = 0.02). Drinkers who consumed shochu most frequentlyshowed a three-fold increased risk over that for beer consumers,although the association disappeared after adjusting for theamount of alcohol consumed. The present results confirm alcoholintake and a preference for high-temperature food to be associatedwith an increased risk of esophageal cancer and show the amountof alcohol consumed, rather than the type of alcoholic beverage,to be the main risk determinant.     

The Japanese guidelines for gastric cancer screening

Background: Gastric cancer is the leading cause of death from cancer inJapan. In 2004, there were 50 562 deaths from gastric cancer;they accounted for 15.8% of the total number of cancer deaths.Since 1983, under the Health Service Law for the Aged, gastriccancer screening has been conducted nationwide for all residentsaged 40 years and over. Methods: On the basis of the standardized method developed for the JapaneseGuidelines for Cancer Screening, the efficacies of various methodsfor gastric cancer screening were evaluated and the guidelinewas developed. Results: Four methods for gastric cancer screening were evaluated: photofluorography,endoscopy, serum pepsinogen testing and Helicobacter pyloriantibody testing. On the basis of the analytic framework involvingkey questions, 1715 articles, published from January 1985 toFebruary 2005, were selected using MEDLINE, the Japanese MedicalResearch Database and other methods. After the systematic literaturereview, 10 articles were identified as direct evidence and 49articles as indirect evidence. The studies that evaluated mortalityreduction from gastric cancer included five case–controland two cohort studies for radiographic screening. On the basisof the balance of benefits and harms, the recommendations forpopulation-based and opportunistic screening were formulated.Gastric cancer screening using photofluorography was recommendedfor both screening programs. The other methods were not recommendedfor population-based screening due to insufficient evidence. Conclusions: The guideline for gastric cancer screening guideline was developedbased on the previously established method. Gastric cancer screeningusing photofluorography is recommended for population-basedand opportunistic screening in Japan.     

Tobacco smoking and breast cancer risk: an evaluation based on a systematic review of epidemiological evidence among the Japanese population

BACKGROUND: Our research group undertook an appraisal of the body of epidemiological studies on cancer in Japan to evaluate the existing evidence concerning the association between health-related lifestyles and cancer. As tobacco smoking may be one of the few modifiable risk factors for breast cancer, we focused on the association between tobacco smoking and the risk of breast cancer in this review. METHODS: A MEDLINE search was conducted to identify epidemiological studies on the association between smoking and breast cancer incidence or mortality among the Japanese from 1966 to 2005. Evaluation of associations was based on the strength of evidence and the magnitude of association, together with biological plausibility as previously evaluated by the International Agency for Research on Cancer. RESULTS: Three cohort studies and eight case-control studies were identified. The relative risk (RR) or odds ratio (OR) of breast cancer for current smokers ranged from 0.71 to 6.26 in these studies. A significantly increased risk among current smokers compared with never smokers (RR = 1.7) was reported in one out of the three cohort studies. Moderate or strong associations between smoking and breast cancer risk (OR > 2.0) were observed in four of the eight case-control studies. Experimental studies have supported the biological plausibility of a positive association between tobacco smoking and breast cancer risk. CONCLUSION: We conclude that tobacco smoking possibly increases the risk of breast cancer in the Japanese population.     

A meta-analysis on alcohol drinking and gastric cancer risk

BackgroundWhether an association between alcohol drinking and gastric cancer risk exists is an open question. In order to provide a definite quantification of the association between alcohol drinking and gastric cancer risk, we conducted a meta-analysis of available data.Patients and methods:We carried out a PubMed search of articles published up to June 2010 and identified 44 case–control and 15 cohort studies, including a total of 34 557 gastric cancer cases. We derived meta-analytic estimates using random-effects models, taking into account correlation between estimates. We carried out a dose–risk analysis using nonlinear random-effects meta-regression models.ResultsCompared with nondrinkers, the pooled relative risk (RR) was 1.07 [95% confidence interval (CI) 1.01–1.13] for alcohol drinkers and 1.20 (95% CI 1.01–1.44) for heavy alcohol drinkers (≥4 drinks per day). The pooled estimates were apparently higher for gastric noncardia (RR for heavy drinkers = 1.17, 95% CI 0.78–1.75) than for gastric cardia (RR = 0.99, 95% CI 0.67–1.47) adenocarcinoma. The dose–risk model estimated a RR of 0.95 (95% CI 0.91–0.99) for 10 g/day and 1.14 (95% CI 1.08–1.21) for 50 g/day.ConclusionsThis meta-analysis provides definite evidence of a lack of association between moderate alcohol drinking and gastric cancer risk. There was, however, a positive association with heavy alcohol drinking.     

Folate, alcohol, and aldehyde dehydrogenase 2 polymorphism and the risk of oral and pharyngeal cancer in Japanese

Folate consumption is inversely associated with the risk of oral and pharyngeal cancer (OPC) and potentially interacts with alcohol drinking in the risk of OPC. Aldehyde dehydrogenase 2 (ALDH2) gene polymorphism is known to interact with alcohol consumption. The aim of this study was to investigate potential interaction between folate, alcohol drinking, and ALDH2 polymorphism in the risk of OPC in a Japanese population. The study group comprised 409 head and neck cancer cases and 1227 age-matched and sex-matched noncancer controls; of these, 251 cases and 759 controls were evaluated for ALDH rs671 polymorphism. Associations were assessed by odds ratios and 95% confidence intervals in multiple logistic regression models. We observed an inverse association between folate consumption and OPC risk. The odds ratio for high folate intake was 0.53 (95% confidence interval: 0.36-0.77) relative to low intake (P trend=0.003). This association was consistent across strata of sex, age, smoking, and ALDH2 genotypes. Interaction between folate consumption, drinking, and ALDH2 genotype was remarkable (three-way interaction, P<0.001). We observed significant interaction among folate, drinking, and ALDH2 genotype in the Japanese population.     

Tobacco smoking and lung cancer risk: an evaluation based on a systematic review of epidemiological evidence among the Japanese population

BACKGROUND: Although tobacco smoking is the best established risk factor for lung cancer, the association is not as strong among Japanese as among Western populations. It would be of value, therefore, to quantify that association in Japan based on a systematic review of epidemiological evidence for the primary prevention of lung cancer. METHODS: Original data were obtained from MEDLINE searches using PubMed, supplemented with manual searches. The evaluation of associations was based on the strength of evidence and the magnitude of the association, together with biological plausibility as previously evaluated by the International Agency for Research on Cancer. A meta-analysis was also conducted to estimate the summary measure of those associations. RESULTS: A total of 8 cohort studies and 14 case-control studies were identified, almost all of which consistently showed a strong association of current smoking with the risk of lung cancer. The summary relative risk for current smokers versus never smokers was estimated as 4.39 (95% confidence interval 3.92-4.92) for men and 2.79 (95% confidence interval 2.44-3.20) for women. Cohort studies and case-control studies gave reasonably consistent summary measures. The summary relative risks were 11.7 and 2.30 for squamous cell carcinoma and adenocarcinoma, respectively, in men, and were 11.3 and 1.37 correspondingly in women. CONCLUSION: There is convincing evidence that tobacco smoking strongly increases the risk of lung cancer in the Japanese population, with the relative risk for current smokers compared with never smokers measuring around 4.4 for men and 2.8 for women.     

A meta-analysis of asthma and risk of lung cancer (United States)

Objective: To review epidemiologic evidence that asthma is a risk factor for lung cancer, with particular attention to the role of smoking on this association. Methods: Through MEDLINE computer searches (January 1966 to April 2002) and a review of references, we identified studies with quantitative data on the relation of asthma to lung cancer. Summary estimates of relative risks (RR) were calculated using the fixed-effects model or the random-effects model as appropriate. Results: The combined results from five case–control studies – that presented data limited to individuals who had never smoked – showed a 1.8-fold increase in lung cancer risk among asthmatics (95% confidence interval (CI) = 1.3–2.3). The results from six case–control and four cohort studies, which controlled for smoking history also were significant (RR = 1.7; 95% CI = 1.3–2.2). Finally, to illustrate the potential confounding by tobacco, we combined data from seven cohort studies that did not control for smoking history and found an overall RR of 1.4 (95% CI = 1.2–1.6). Conclusions: The increased risk of lung cancer among never smoking individuals with asthma supports a direct relation between asthma and lung cancer. There is biological evidence to support this association.     

Prospective study of alcohol consumption and breast cancer risk in Japanese women

Epidemiologic evidence is lacking for the association between alcohol consumption and the risk of breast cancer in Japanese women. We addressed this association in a prospective cohort study with an average follow-up of 7.6 years. At baseline (1988-1990), cohort participants completed a self-administered questionnaire that included alcohol use, reproductive history and hormone use. The women were followed up for breast cancer incidence through December 31, 1997. Cox proportional hazards models were used to calculate relative risks (RRs) and 95% confidence intervals (CIs) for breast cancer incidence and any association with alcohol consumption. During a follow-up of 271,412 person-years, we identified 151 women with breast cancer, of whom 45 were current drinkers and 11 drank > or =15 g of alcohol/day. After adjustment for age and other potential risk factors for breast cancer, the RR for current drinkers was 1.27 (95% CI 0.87-1.84) compared to nondrinkers. Average alcohol intake of <15 g/day did not significantly increase the risk for breast cancer. However, risk was significantly increased for women who consumed > or =15 g/day of alcohol (RR = 2.93, 95% CI 1.55-5.54). Age at starting drinking and frequency of consumption per week were not significantly associated with breast cancer risk. Our cohort study demonstrated that Japanese women who consume at least a moderate amount of alcohol have an increased risk of breast cancer.     

No Effect of Energy Intake Overall on Risk of Endometrial Cancers: a Meta-analysis

Background: Previous epidemiologic studies on the association between energy intake and endometrial cancerrisk have only generated contradictory results. The role of energy intake in endometrial carcinogenesis thusremains unclear. To quantitatively assess the potential association between energy intake and endometrial cancer,a meta-analysis of case-control and cohort studies was here conducted. Materials and Methods: Eligible studieswere retrieved via both computerized searches and review of references. Fixed-or random-effect models were usedto summarize the estimates of OR with 95%CIs. Stratified analyses on study design, region and macronutrients’calorie were performed. Results: Sixteen studies met the inclusion criteria of the meta-analysis. No associationbetween total energy intake and endometrial cancer was observed in either overall group (OR=1.11, 95%CI0.92-1.30) or subgroups stratified by study design and region. In the specific macronutrients’ calorie analysis,higher fat energy intake was found to be associated with increased endometrial risk (OR=1.72, 95%CI 1.12-2.32) while energy from carbohydrate and protein was not related to endometrial cancer risk. Conclusions: Ouranalysis did not support that total energy intake is related to endometrial cancer risk, in contrast to fat energy.     

Green Tea Consumption and Subsequent Risk of Gastric Cancer by Subsite: The JPHC Study

OBJECTIVE: To investigate the relationship between green tea consumption and subsequent risk of gastric cancer at different anatomical subsites in a population-based prospective study. METHODS: The Japan Public Health Center-based prospective study (JPHC Study) was established in 1990 for Cohort I and in 1993 for Cohort II. Among 72,943 subjects (34,832 men and 38,111 women), 892 gastric cancer cases (665 men and 227 women) were identified from 1990 to 2001. RESULTS: While no association between green tea consumption and gastric cancer was observed among men, a decreased risk of gastric cancer was observed among women after adjustment for potential confounding factors. This result was more remarkable when only the tumors in the distal portion were analyzed; for that subsite, the relative risk was 0.51 (95% confidence interval 0.30-0.86) in the highest category of green tea consumption (5 or more cups per day versus less than 1 cup per day) (p for trend = 0.01). The null association for upper-third gastric cancer was consistent for both sexes. CONCLUSIONS: An inverse association between green tea consumption and distal gastric cancer was observed among women. More prospective studies with detailed information are needed to confirm the role of green tea in the occurrence of gastric cancer.