Smoking, alcohol and gastric cancer risk in Korean men: the National Health Insurance Corporation Study

We investigated the risk of gastric cancer by subsite in relation to cigarette smoking and alcohol in a large population-based cohort of 669 570 Korean men in an insurance plan followed for an average 6.5 years, yielding 3452 new cases of gastric cancer, of which 127 were cardia and upper-third gastric cancer, 2409 were distal gastric cancer and 1007 were unclassified. A moderate association was found between smoking, cardia and upper-third (adjusted relative risk (aRR) 2.2; 95% confidence interval (CI) 1.4-3.5) and distal cancers (aRR=1.4; 95% CI=1.3-1.6). We also found a positive association between alcohol consumption and distal (aRR=1.3; 95% CI=1.2-1.5) and total (aRR=1.2; 95% CI=1.1-1.4) gastric cancer. Combined exposure to high levels of tobacco and alcohol increased the risk estimates further; cardia and upper-third gastric cancers were more strongly related to smoking status than distal gastric cancer.British Journal of Cancer (2007) 97, 700-704. doi:10.1038/sj.bjc.6603893 www.bjcancer.com Published online 17 July 2007.     

Pancreatic cancer and factors associated with the insulin resistance syndrome in the Korean cancer prevention study

There is increasing evidence that type 2 diabetes mellitus and glucose intolerance are a cause, not just a consequence, of pancreatic cancer. We examined whether other factors that characterize the insulin resistance syndrome are also risk factors for pancreatic cancer in a prospective cohort study of 631,172 men and women (ages 45+ years) who received health insurance from the Korean Medical Insurance Corporation. The biennial medical evaluations from 1992 to 1995 provided the baseline information for this study. Relative risks (RR) were estimated using proportional hazards models adjusted for age, sex, smoking, and fasting serum glucose (after excluding the first 2 years of follow-up). There were 2,194 incident cases of pancreatic cancer diagnosed in the cohort over a median follow-up of 12 years. There was no evidence that pancreatic cancer risk was associated with total cholesterol, systolic blood pressure, WBC count, or body mass index. Abnormal levels of aspartate aminotransferase and alanine aminotransferase were both associated with a moderately increased risk of developing the disease (40+ versus <20; RR, 1.33; 95% CI, 1.14-1.55; P(trend) = 0.05 and RR, 1.34; 95% CI, 1.16-1.56; P(trend) = 0.02, respectively). Excluding 6 years of follow-up reduced this RR (95% CI) for aspartate aminotransferase to 1.22 (1.01-1.49), but even after excluding 10 years follow-up the RR (95% CI) for alanine aminotransferase was unchanged [1.36 (1.01-1.83)]. Although fasting serum glucose has been found previously to be associated with pancreatic cancer risk in this cohort, most other factors that characterize insulin resistance syndrome were not associated with pancreatic cancer risk. The association with elevated liver enzyme levels is a novel finding that warrants further investigation.     

A prospective cohort study of cigarette smoking and pancreatic cancer in Japan

Objective: To examine the association of cigarette smoking with the risk of death from pancreatic cancer in a prospective cohort study. Methods: A total of 110,792 inhabitants, aged 40–79 years (46,465 men and 64,327 women), were enrolled from 1988 to 1990 and followed up for mortality to the end of 1997. At baseline a self-administered questionnaire was used to obtain information on cigarette smoking and other lifestyle factors. Results: During the follow-up period (mean ± SD: 8.1 ± 1.8 years), 225 deaths due to pancreatic cancer were identified. After adjustment for age, body mass index, history of diabetes mellitus, and gallbladder diseases, the relative risks (RRs) for current smokers were 1.6 (95% CI 0.95–2.6) in males, and 1.7 (95% CI: 0.84–3.3) in females. Men who smoked more than 40 cigarettes per day had a substantially higher risk of pancreatic cancer, with a RR of 3.3 (95% CI: 1.4–8.1). A significantly decreasing trend in risk with increasing years after smoking cessation was observed (trend p = 0.04) among male ex-smokers. The RRs were 0.85 (95% CI 0.36–2.0) and 0.85 (0.36–2.0) for those who had quit smoking for 10–19 and 20 years, respectively. Conclusions: Our cohort study confirmed that cigarette smoking was associated with an increased risk of death from pancreatic cancer.     

Smoking and bladder cancer in Spain: effects of tobacco type, timing, environmental tobacco smoke, and gender.

We examined the effects of dose, type of tobacco, cessation, inhalation, and environmental tobacco smoke exposure on bladder cancer risk among 1,219 patients with newly diagnosed bladder cancer and 1,271 controls recruited from 18 hospitals in Spain. We used unconditional logistic regression to estimate odds ratios (OR) and 95% confidence intervals (95% CI) for the association between bladder cancer risk and various characteristics of cigarette smoking. Current smokers (men: OR, 7.4; 95% CI, 5.3-10.4; women: OR, 5.1; 95% CI, 1.6-16.4) and former smokers (men: OR, 3.8; 95% CI, 2.8-5.3; women: OR, 1.8; 95% CI, 0.5-7.2) had significantly increased risks of bladder cancer compared with nonsmokers. We observed a significant positive trend in risk with increasing duration and amount smoked. After adjustment for duration, risk was only 40% higher in smokers of black tobacco than that in smokers of blond tobacco (OR, 1.4; 95% CI, 0.98-2.0). Compared with risk in current smokers, a significant inverse trend in risk with increasing time since quitting smoking blond tobacco was observed (> or =20 years cessation: OR, 0.2; 95% CI, 0.1-0.9). No trend in risk with cessation of smoking black tobacco was apparent. Compared with men who inhaled into the mouth, risk increased for men who inhaled into the throat (OR, 1.7; 95% CI, 1.1-2.6) and chest (OR, 1.5; 95% CI, 1.1-2.1). Cumulative occupational exposure to environmental tobacco smoke seemed to confer increased risk among female nonsmokers but not among male nonsmokers. After eliminating the effect of cigarette smoking on bladder cancer risk in our study population, the male-to-female incidence ratio decreased from 8.2 to 1.7, suggesting that nearly the entire male excess of bladder cancer observed in Spain is explained by cigarette smoking rather than occupational/environmental exposures to other bladder carcinogens.     

Risk of gastroesophageal cancer among smokers and users of Scandinavian moist snuff

Although Scandinavian moist snuff ("snus"), no doubt, is a safer alternative to smoking, there is limited evidence against an association with gastroesophageal cancers. In a retrospective cohort study, we investigated esophageal and stomach cancer incidence among 336,381 male Swedish construction workers who provided information on tobacco smoking and snus habits within a health surveillance program between 1971 and 1993. Essentially complete follow-up through 2004 was accomplished through linkage to several nationwide registers. Multivariable Cox proportional hazards regression models estimated relative risks (RR) and 95% confidence intervals (CIs). Compared to never-users of any tobacco, smokers had increased risks for adenocarcinoma (RR = 2.3, 95% CI 1.4-3.7) and squamous cell carcinoma (RR = 5.2, 95% CI 3.1-8.6) of the esophagus, as well as cardia (RR = 2.1, 95% CI 1.5-3.0) and noncardia stomach (RR = 1.3, 95% CI 1.2-1.6) cancers. We also observed excess risks for esophageal squamous cell carcinoma (RR = 3.5, 95% CI 1.6-7.6) and noncardia stomach cancer (RR = 1.4, 95% CI 1.1-1.9) among snus users who had never smoked. Although confounding by unmeasured exposures, and some differential misclassification of smoking, might have inflated the associations, our study provides suggestive evidence for an independent carcinogenic effect of snus.     

Passive smoking and the use of noncigarette tobacco products in association with risk for pancreatic cancer: a case-control study

BACKGROUND: The associations between passive smoking and the use of noncigarette tobacco products with pancreatic cancer are not clear. METHODS: In this case-control study, the authors collected information on passive smoking and the use of noncigarette tobacco products in 808 patients with pancreatic adenocarcinoma and 808 healthy controls by personal interview. Multivariable logistic regression was performed to estimate the adjusted odds ratio (AOR) and 95% confidence interval (95% CI). RESULTS: The results confirmed the previously reported association between active smoking and increased risk for pancreatic cancer. The AOR was 1.7 (95% CI, 1.4-2.2) for regular smokers, 1.8 (95% CI, 1.4-2.4) for long-term smokers, and 3.1 (95% CI, 2.2-4.3) for former smokers. Although passive smoking showed a nonsignificantly elevated risk for pancreatic cancer in the entire study population (AOR, 1.3; 95% CI, 0.9-1.7), the association was present among ever smokers (AOR, 1.7; 95% CI, 1.03-2.6) but was absent among never smokers (AOR, 1.1; 95% CI, 0.8-1.6). Neither intensity nor duration of passive smoking modified the risk of pancreatic cancer among never smokers. The use of chewing tobacco, snuff, and pipes showed no significant risk elevation for pancreatic cancer after controlling for the confounding effects of demographics and other known risk factors. The use of cigars in never smokers showed a borderline significant increase of risk for pancreatic cancer (AOR, 2.2; 95% CI, 1.0-4.7; P = .05). CONCLUSIONS: The current observations did not support a role for passive smoking or the use of noncigarette tobacco products in the etiology of pancreatic cancer. The association between cigar use and the risk of pancreatic cancer needs to be confirmed in other study populations.     

A prospective study on active and environmental tobacco smoking and bladder cancer risk (The Netherlands)

Objective: In a prospective cohort study among 120,852 adult subjects the authors investigated the associations between cigarette, cigar, pipe, environmental tobacco smoking (ETS), and bladder cancer. Methods: In 1986 all subjects completed a questionnaire on cancer risk factors. Follow-up for incident bladder cancer was established by linkage to cancer registries until 1992. The case–cohort analysis was based on 619 cases and 3346 subcohort members. Results: Compared with lifelong non-smokers the age- and sex-adjusted incidence rate ratios (RR) for ex- and current cigarette smokers were 2.1 (95% CI 1.5–3.0) and 3.3 (95% CI 2.4–4.6), respectively. The RR for smoking duration was 1.03 (95% CI: 1.02–1.04) per 1-year increment. The RR per 10 cigarettes/day was 1.3 (95% CI 1.2–1.4). Tar and nicotine exposure increased bladder cancer risk only weakly. It appeared that associations of cigarette smoking characteristics with bladder cancer risk were largely attributable to cigarette smoking duration only. Smoking cessation, age at first exposure, filter-tip usage, cigar and pipe smoking, and ETS were no longer associated with bladder cancer risk after adjustment for frequency and duration of smoking. Conclusions: The authors conclude that current cigarette smokers have a three-fold higher bladder cancer risk than non-smokers. Ex-smokers experience a two-fold increased risk. About half of male bladder cancer and one-fifth of female bladder cancer was attributable to cigarette smoking. Other smoking types (cigar, pipe, or ETS) were not associated with increased risks.     

Overall obesity, abdominal adiposity, diabetes and cigarette smoking in relation to the risk of pancreatic cancer in two Swedish population-based cohorts

We examined the associations of body mass index (BMI), waist circumference, a history of diabetes, and cigarette smoking with risk of pancreatic cancer among 37,147 women and 45,906 men followed up during 560,666 person-years in the Swedish Mammography Cohort and the Cohort of Swedish Men; 136 incident cases of pancreatic cancer were diagnosed. The multivariate rate ratio (RR) of pancreatic cancer for obese women and men (BMI > or =30 kg/m(2)) was 1.81 (95% CI: 1.04-3.15) compared to those with a BMI of 20-25 kg/m(2). For a difference of 20 cm (about two standard deviations) in waist circumference, the multivariate RRs were 1.32 (95% CI: 0.73-2.37) among women and 1.74 (95% CI: 1.00-3.01) among men. Pancreatic cancer risk was associated with history of diabetes (multivariate RR: 1.88; 95% CI: 1.09-3.26) and cigarette smoking (multivariate RR for current compared with never smokers: 3.06; 95% CI: 1.99-4.72). Current smokers of > or =40 pack-years had a five-fold elevated risk compared with never smokers. Risk among past smokers approached the RR for never smokers within 5-10 years following smoking cessation. Findings from this prospective study support positive relationships of overall obesity, abdominal adiposity, diabetes and smoking with risk of pancreatic cancer.     

Smoking and Cancer Risk in Korean Men and Women

OBJECTIVE: In Korea, male smoking prevalence is among the world's highest, and mortality rates from smoking-caused cancers, particularly lung cancer, are escalating. This cohort study examined the effects of cigarette smoking on the risk of cancer mortality and incidence, and characterized the relationship of cancer risk with the amount and duration of cigarette smoking. METHOD: A nine-year prospective cohort study was carried out on 1,212,906 Koreans, 30-95 years of age. The study population includes participants in a national insurance program, who completed a questionnaire on smoking and other risk factors. The main outcome measures were death from cancer and cancer incidence, obtained through record linkage. At baseline, 472,970 men (57.0%) and 20,548 (5.4%) women were current cigarette smokers. RESULTS: In multivariate Cox proportional hazards models, controlling for age, current smoking among men increased the risks of mortality for cancer of the lung (relative risk (RR), 4.6; 95% confidence interval (CI), 4.0-5.3) and other cancers, including larynx, bile duct, esophagus, liver, stomach, pancreas, bladder, and also leukemia. Current smoking among women increased the risk of lung cancer mortality (RR = 2.5, 95% CI = 2.0-3.1). Similar results were found for incidence among men and women. CONCLUSION: In Korea, smoking is an independent risk factor for a number of major cancers. The findings affirm the need for aggressive tobacco control in Korea in order to minimize the epidemic of smoking-caused disease.     

Marijuana use and cancer incidence (California, United States)

The purpose of this retrospective cohort study was to examine therelationship of marijuana use to cancer incidence. The study populationconsisted of 64,855 examinees in the Kaiser Permanente multiphasic healthcheckup in San Francisco and Oakland (California, United States), between1979-85, aged 15 to 49 years, who completed self-ad-ministered questionnairesabout smoking habits, including marijuana use. Follow-up for cancer incidencewas conducted through 1993 (mean length 8.6 years). Compared withnonusers/experimenters (lifetime use of less than seven times), ever- andcurrent use of marijuana were not associated with increased risk of cancer ofall sites (relative risk [RR] = 0.9, 95 percent confidence interval [CI] =0.7-1.2 for ever-use in men; RR = 1.0, CI = 0.8-1.1 in women) in analysesadjusted for sociodemographic factors, cigarette smoking, and alcohol use.Marijuana use also was not associated with tobacco-related cancers or withcancer of the following sites: co lorectal, lung, melanoma, prostate, breast,cervix. Among nonsmokers of tobacco cigarettes, ever having used marijuanawas associated with increased risk of prostate cancer (RR = 3.1, CI =1.0-9.5) and nearly significantly increased risk of cervical cancer (RR =1.4, CI = 1.0-2.1). We conclude that, in this relatively young study cohort,marijuana use and cancer were not associated in overall analyses, but thatassociations in nonsmokers of tobacco cigarettes suggested that marijuana usemight affect certain site-specific cancer risks.     

Relative and absolute risks of cigarette smoking on major histologic types of lung cancer in Korean men.

OBJECTIVES: Most prospective cohort studies of lung cancer focus on the relative risk rather than the absolute risk of smoking. METHODS: This prospective study included 437,976 Korean men (cohort for the National Health Insurance Cooperation Study), > or = 40 years old, who were free of cancer and smoking-related chronic disease at the time of enrollment. Based on new incidence cases, relative risk and excess risk, and their 95% confidence intervals (95% CI), were estimated with the standard Poisson regression model after adjustment for age or other demographic factors and other confounders. RESULTS: During the 6-year follow-up period of 3,142,451 person-years, 1,357 new lung cancer cases were identified. Based on the multivariate-adjusted relative risk for current smokers, the strongest association with smoking was shown for small-cell lung cancer (relative risk, 21.7; 95% CI, 8.0-58.5) followed by squamous cell carcinoma (relative risk, 11.7; 95% CI, 7.1-19.4) and then adenocarcinoma (relative risk, 2.1; 95% CI, 1.6-2.7). In current smokers with > or = 40 pack-years of exposure, excess risk was highest for squamous cell carcinoma (excess risk, 33.8; 95% CI, 10.2-109.8) followed by adenocarcinoma (excess risk, 26.7; 95% CI, 10.3-64.4), and then small-cell carcinoma (excess risk, 16.3; 95% CI, 1.8-144.3). CONCLUSIONS: In Korean men, cigarette smoking was as important a risk factor for adenocarcinoma as it was for squamous cell and small-cell lung cancer.     

Alcohol consumption, smoking, and subsequent risk of colorectal cancer in middle-aged and elderly Japanese men and women: Japan Public Health Center-based prospective study.

Few studies have examined the association of alcohol consumption and cigarette smoking with colorectal cancer in Asian populations whose genetic susceptibility to these factors are different from Western populations. We investigated this association and the joint effect of these factors, and estimated the population-attributable fraction to clarify the public health impact on a Japanese population, based on a prospective study. We analyzed the 10-year (cohort I) and 7-year (cohort II) follow-up data of the Japan Public Health Center-based prospective study on cancer and cardiovascular disease, derived from 90,004 (42,540 male and 47,464 female) middle-aged and elderly Japanese. We identified 716 (457 in men and 259 in women) newly diagnosed cases of colorectal cancer. Both alcohol consumption and smoking were clearly associated with colorectal cancer in men, after adjusting for age, family history of colorectal cancer, body mass index, and physical exercise. Regular heavy drinking of 150 g/week or more of ethanol showed a statistically significant increased risk compared with nondrinkers: relative risks (RRs) were 1.4 [95% confidence interval (CI), 1.1-1.9] for 150-299 g/week and 2.1 (95% CI, 1.6-2.7) for 300 g/week or more. On the contrary, regular ethanol consumption was not associated with colorectal cancer (RR, 0.7; 95% CI, 0.4-1.1) in women. In terms of smoking, the RRs were 1.4 (95% CI, 1.1-1.8) for current smokers and 1.3 (95% CI, 0.98-1.7) for ex-smokers compared with never-smokers in men. The risk of smoking in women was similar to that in men, although not statistically significant. The colorectal cancer risk with 300 g/week or more of ethanol in current smokers was estimated at 3.0 (95% CI, 1.8-5.1) compared with nondrinkers among nonsmokers in men. Colorectal cancer attributable to alcohol consumption or smoking was estimated to be 46%. In conclusion, approximately half of the colorectal cancer cases may be preventable by tobacco and alcohol controls in middle-aged and elderly Japanese men.     

Cigarette smoking,use of other tobacco products and stomach cancer mortality in US adults: The Cancer Prevention Study II

Cigarette smoking is associated with increased risk of stomach cancer in many studies but there are limited data on this relationship in women and on risk associated with use of tobacco products other than cigarettes. We examined stomach cancer death rates in relation to cigarette smoking in women and use of cigarette, cigar, pipe, or smokeless tobacco in men in a nationwide prospective mortality study in the United States (US). Cohort follow-up from 1982-96 identified 996 and 509 stomach cancer deaths among 467,788 men and 588,053 women, respectively. Cox proportional hazards models were fitted to estimate rate ratios (RR) and 95% confidence intervals (CI) using non-users of tobacco as the referent group. Multivariate-adjusted RRs were the highest for men who currently smoked cigars (RR = 2.29, 95% CI = 1.49-3.51) or cigarettes (RR = 2.16, 95% CI = 1.75-2.67) and both increased with smoking duration. Women who currently (RR = 1.49, 95% CI = 1.18-1.88) or formerly (RR = 1.36, 95% CI = 1.08-1.71) smoked cigarettes were at significantly increased risk, as were men who formerly smoked cigarettes (RR = 1.55, 95% CI = 1.28-1.88), or currently (RR = 1.81, 95% CI = 1.40-2.35) or formerly (RR: 1.57, 95% CI = 1.22-2.03) used more than one type of tobacco. Men who reported a history of chronic indigestion or gastroduodenal ulcer had substantially higher mortality rates associated with current cigarette (RR = 3.45, 95% CI = 2.05-5.80) or cigar (RR = 8.93, 95% CI = 4.02-19.90) smoking, as did men who were current aspirin users. If causal, the estimated proportion of stomach cancer deaths attributable to tobacco use would be 28% in US men and 14% in women. We conclude that prolonged use of tobacco products is associated with increased stomach cancer mortality in men and women. The accumulated evidence from this and other studies support reconsidering stomach cancer as a tobacco-related cancer.     

The Copenhagen case-control study of renal pelvis and ureter cancer: role of smoking and occupational exposures

Smoking habits and occupational exposures were investigated for 96 patients with cancer of the renal pelvis and ureter (including papilloma) and 294 hospital controls. In comparison with persons who never smoked, significantly increased relative risks were seen for smokers of cigarettes alone (RR = 2.6; 95% CI: 1.0-6.7) and in combination with other types of tobacco (RR = 3.8; 95% CI: 1.3-11.5). Non-significantly increased relative risks were observed for pipe smokers (RR = 2.2; 95% CI: 0.1-97) and for mixed pipe, cigar, and cigarillo smokers (RR = 6.5; 95% CI: 0.4-21.2). A strong dose-effect (p less than 0.001) relationship was seen between the lifetime total amount of tobacco smoked and the risk of pelvis-ureter tumors, with the heaviest smokers having an 8-fold risk. Comparison with the dose-effect relationship for a parallel study of bladder cancer indicated that the relationship with tobacco was stronger for pelvis-ureter tumors. Deep inhalation of cigarette smoke increased the risk (RR = 3.4; 95% CI: 1.9-6.1), while stopping smoking (RR = 0.6; 95% CI: 0.3-1.1) and use of filter cigarettes (RR = 0.5; 95% CI: 0.3-0.9) decreased the risk. Significantly increased risks emerged for employment in the chemical, petrochemical and plastics industries (RR = 4.0; 95% CI: 1.6-9.8), and for exposure to coal and coke (RR = 4.0; 95% CI: 1.2-13.6), asphalt and tar (RR = 5.5; 95% CI: 1.6-19.6). Cigarette smoking accounted for 56% of male and 40% of female pelvis and ureter tumors in eastern Denmark.     

Cancer morbidity in alcohol abusers.

Data on the association between alcohol abuse and cancer morbidity are scarce in large cohorts of non-hospitalised alcoholic men and women. Of 18,368 alcohol abusers who entered an outpatient clinic in Copenhagen during 1954-87, 18,307 were followed and their cancer incidence was compared with that of the total Danish population. On average the 15,214 men were observed for 12.9 years and the 3,093 women for 9.4 years. The overall morbidity of cancer was increased significantly. Of the men, 1,441 developed cancer [relative risk (RR) = 1.6; 95% confidence interval (CI) = 1.5-1.7], while 182 women did (RR = 1.5; 95% CI 1.3-1.8). Significantly increased incidences were found of cancer in the tongue, mouth, pharynx, oesophagus, liver, larynx, lung and pleura and secondary cancer. The women had significantly increased risk of cervical cancer (RR = 2.0; 95% CI 1.2-3.0). The men developed prostatic cancer significantly more frequently than expected (RR = 1.4; 95% CI 1.2-1.8). The risk of melanomas (RR = 0.5; 95% CI 0.2-0.8) was significantly lower than expected. The relative risks of cancer of the stomach, pancreas, kidney and endocrine system were only slightly increased. The study group did not develop more colonic (RR = 1.0; 95% CI 0.8-1.3) or rectal cancer (RR = 1.0; CI 0.7-1.3) than expected. The risk of breast cancer in women was slightly increased (RR = 1.3; 95% CI 0.9-1.7), but not statistically significant. Thus, the associations between alcohol and cancer of the upper digestive and respiratory tract and the liver are confirmed. In addition, this study indicates an increased occurrence of cancer of the prostate gland, pleura and uterine cervix in alcohol abusers.     

A prospective study of periodontal disease and pancreatic cancer in US male health professionals

Two previous cohort studies reported positive associations between tooth loss or periodontitis and pancreatic cancer risk. Data on periodontal disease were obtained at baseline and every other year thereafter in a cohort of 51,529 male health professionals aged 40-75 years. A total of 216 patients were diagnosed with incident pancreatic cancer during 16 years of follow-up. Multivariable relative risks (RRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models controlling for potential confounders, including detailed smoking history. All statistical tests were two-sided. Compared with no periodontal disease, history of periodontal disease was associated with increased pancreatic cancer risk (overall, multivariable RR = 1.64, 95% CI = 1.19 to 2.26; P = .002; crude incidence rates: 61 versus 25 per 100,000 person-years; among never smokers, multivariable RR = 2.09, 95% CI = 1.18 to 3.71; P = .01; crude incidence rates: 61 versus 19 per 100,000 person-years). In contrast, baseline number of natural teeth and cumulative tooth loss during follow-up were not strongly associated with pancreatic cancer. The association between periodontal disease and increased risk of pancreatic cancer may occur through plausible biologic mechanisms, but confirmation of this association is necessary.     

Circulating insulin-like growth factor binding protein-1 and the risk of pancreatic cancer

Insulin-like growth factor (IGF)-I has growth-promoting effects on pancreatic cancer cells, and elevated fasting serum insulin has been linked to pancreatic cancer risk. IGF binding protein-1 (IGFBP-1) is a downstream target of insulin and inhibits IGF-I activity. To investigate whether prediagnostic plasma levels of IGFBP-1 are associated with pancreatic cancer risk, we did a prospective, case-control study nested within the Health Professionals Follow-up Study, the Nurses' Health Study, the Physicians' Health Study, and the Women's Health Initiative. We assayed circulating IGFBP-1 among 144 pancreatic cancer cases that occurred >or=4 years after plasma collection and in 429 controls, matched for date of birth, prospective cohort, smoking status, and fasting status. When compared with participants in the three highest quartiles of plasma IGFBP-1, those in the lowest quartile experienced a relative risk (RR) for pancreatic cancer of 2.07 [95% confidence intervals (95% CI), 1.26-3.39], after adjusting for other risk factors, including circulating IGF-I, IGF binding protein-3, and C-peptide. Only participants in the lowest quartile of plasma IGFBP-1 showed an elevated risk of pancreatic cancer. The influence of low plasma IGFBP-1 became progressively stronger with time; among cases diagnosed >or=8 years after blood collection, the adjusted RR was 3.47 (95% CI, 1.48-8.14), comparing the bottom versus the top three quartiles. The influence of plasma IGFBP-1 was most marked among participants who never smoked cigarettes (RR, 3.30; 95% CI, 1.48-7.35). Among participants in four U.S. prospective cohort studies, low plasma IGFBP-1 levels significantly predicted an increased risk of pancreatic cancer.     

Active and passive smoking and breast cancer risk in middle-aged Japanese women

To examine the hypothesis that tobacco smoke is associated with the risk of female breast cancer, we estimated the relative risks of active and passive smoke in middle-aged Japanese women in a population-based prospective study. The cohort consisted of residents in 4 public health center areas, aged 40 to 59 years. A self-administered questionnaire survey was conducted in 1990. This analysis included 21,805 subjects, 180 of whom had developed breast cancer by December 31, 1999. When the reference was defined as never-active smokers without passive smoking, adjusted relative risks (RRs) were 1.9 (95% confidence interval [CI] = 1.0-3.6) in current active smokers, 1.2 (95% CI = 0.4-4.0) in ex-active smokers and 1.2 (95% CI = 0.8-1.6) in never-active smokers with passive smoking. The elevated risk for ever-smokers was clearly observed in premenopausal women at baseline (RR = 3.9, 95% CI = 1.5-9.9) but not in postmenopausal women (RR = 1.1, 95% CI = 0.5-2.5). In never-active smokers, the adjusted RR for passive smoking, residential or occupational/public tobacco smoke exposure was 1.1 (95% CI = 0.8-1.6). In premenopausal women, passive smoking increased the risk (RR = 2.6; 95% CI = 1.3-5.2) but not in postmenopausal women (RR = 0.7; 95% CI = 0.4-1.0). We conclude that tobacco smoking increases the risk of female breast cancer in premenopausal women.     

Smoking and gastric cancer: systematic review and meta-analysis of cohort studies

OBJECTIVE: We conducted a systematic review of studies addressing the relation between cigarette smoking and gastric cancer to estimate the magnitude of the association for different levels of exposure and cancer locations. METHODS: Published cohort, case-cohort, and nested case-control studies were identified through PubMed, Scopus, and Web of Science searches, from inception to July 2007. Relative risk (RR) estimates referring to the comparison of two categories of exposure (e.g., current smokers vs. never smokers) were combined using a random effects model. Generalized least squares regression was used for trend estimation. Heterogeneity was quantified using the I (2) statistic. RESULTS: Forty-two articles were considered for the systematic review. Comparing current smokers with never smokers: the summary RR estimates were 1.62 in males (95% CI: 1.50-1.75; I (2) = 46.0%; 18 studies) and 1.20 in females (95% CI: 1.01-1.43; I (2) = 49.8%; nine studies); the RR increased from 1.3 for the lowest consumptions to 1.7 for the smoking of approximately 30 cigarettes per day in the trend estimation analysis; smoking was significantly associated with both cardia (RR = 1.87; 95% CI: 1.31-2.67; I (2) = 73.2%; nine studies) and non-cardia (RR = 1.60; 95% CI: 1.41-1.80; I (2) = 18.9%; nine studies) cancers. CONCLUSION: Our study provides solid evidence to classify smoking as the most important behavioral risk factor for gastric cancer.     

Increased blood glucose and insulin, body size, and incident colorectal cancer.

BACKGROUND: Abdominal obesity--an elevated level of visceral adipose tissue--has been linked to colorectal cancer. Furthermore, elevated levels of visceral adipose tissue have been associated with hyperinsulinemia, and insulin is a growth factor in the colon. We assessed whether waist circumference, a surrogate measure of visceral adipose tissue, and metabolic parameters associated with visceral adipose tissue were related to colorectal cancer. METHODS: In the Cardiovascular Health Study cohort, we examined the relationship of baseline measurements of body size, glucose, insulin, and lipoproteins to incident colorectal cancer. All P values are two-sided. RESULTS: Among 5849 participants, 102 incident cases of colorectal cancer were identified. Individuals in the highest quartile of fasting glucose had a nearly twofold increased risk of colorectal cancer (relative risk [RR] = 1.8; 95% confidence interval [CI] = 1.0-3.1), and the linear trend RR (LT RR = 1.2; 95% CI = 1.0-1.5) for fasting glucose level was statistically significant (P =. 02). Glucose and insulin levels 2 hours after oral glucose challenge also exhibited statistically significant associations with colorectal cancer (2-hour glucose levels: RR = 2.4 [95% CI = 1.2-4. 7]/LT RR = 1.3 [95% CI = 1.0-1.6; P =.02]; 2-hour insulin levels: RR = 2.0 [95% CI = 1.0-3.8]/LT RR = 1.2 [95% CI = 1.0-1.5; P =.04]). Analysis of fasting insulin levels suggested a threshold effect, with values above the median associated with colorectal cancer (RR = 1.6; 95% CI = 1.1-2.4; P =.02). Higher levels of waist circumference were also statistically significantly associated with colorectal cancer (RR = 1.9; 95% CI = 1.1-3.3; P =.02). CONCLUSIONS: These data provide, to our knowledge, the first direct evidence of an association between elevated visceral adipose tissue level, its associated metabolic effects, and colorectal cancer.