Dietary B vitamin and methionine intakes and lung cancer risk among female never smokers in China

Purpose

B vitamins and methionine have been postulated to have potential effects on carcinogenesis; however, findings from previous epidemiologic studies on B vitamins, methionine, and lung cancer risk are inconsistent. We investigated associations of dietary intakes of B vitamins (i.e., riboflavin, niacin, vitamin B6, folate, and vitamin B12) and methionine with lung cancer risk among female never smokers.

Methods

The Shanghai Women’s Health Study, a population-based, prospective cohort study, included 74,941 women. During a median follow-up of 11.2?years, 428 incident lung cancer cases accrued among 71,267 women with no history of smoking or cancer at baseline. Baseline dietary intakes were derived from a validated, interviewer-administered food frequency questionnaire. Cancer incidence and vital status were ascertained through annual linkage to the Shanghai Cancer Registry and Shanghai Vital Statistics Registry databases and through biennial in-person follow-ups with participants. Adjusted hazard ratios (HR) and 95?% confidence intervals (CI) were calculated using Cox regression.

Results

Dietary riboflavin intake was inversely associated with lung cancer risk (HR?=?0.62; 95?% CI?=?0.43–0.89; p trend?=?0.03 for the highest quartile compared with the lowest). A higher than median intake of methionine was associated with lower risk of lung cancer (HR?=?0.78; 95?% CI?=?0.60–0.99); however, there was no dose–response relation. Intakes of other B vitamins were not associated with lung cancer risk.

Conclusions

Our study suggests that dietary riboflavin intake may be inversely associated with lung cancer risk among female never smokers, which warrants further investigation.     

Dietary folate intake and lung cancer risk in former smokers: a case-control analysis.

No studies have focused on the role of dietary folate intake in risk of lung cancer in former smokers, in whom dietary folate intake is less likely confounded with current smoking. Therefore, we evaluated the association between dietary folate intake and risk of lung cancer in a population of 470 histopathologically confirmed incident lung cancer cases from M. D. Anderson Cancer Center and 472 cancer-free controls from enrollees at a community-based multispecialty physician practice, frequency-matched on age (5 years), sex, and ethnicity. Dietary folate intake levels were estimated from a National Cancer Institute standard food frequency questionnaire. Unconditional logistic regression analyses were used to calculate the crude and adjusted ORs and their 95% CIs. Dietary folate intake from natural food was significantly higher among the controls than among the cases (P < 0.001), and folate intake above the control median value was associated with a 40% decreased risk of lung cancer (adjusted OR, 0.60; 95% CI, 0.45-0.79). A significant inverse dose-response relationship between increasing dietary folate and decreasing risk of lung cancer was also evident (adjusted OR, 1.02; 95% CI, 0.71-1.47; OR, 0.67; 95% CI, 0.46-0.99; and OR, 0.53; 95% CI, 0.35-0.80 for the second, third, and fourth quartiles of average folate intake, respectively; P for trend <0.001). A more pronounced inverse association between dietary folate intake and lung cancer risk was observed among subjects who drank alcohol, had smoked relatively more, those who did not take supplemental folate, and those who reported a family history of lung cancer. Our data suggest that there is a possible protective role of dietary folate in lung carcinogenesis, a finding which may have implications in public health and cancer prevention.     

Dietary intake of acrylamide and endometrial cancer risk in the European Prospective Investigation into Cancer and Nutrition cohort

Background:

Three prospective studies have evaluated the association between dietary acrylamide intake and endometrial cancer (EC) risk with inconsistent results. The objective of this study was to evaluate the association between acrylamide intake and EC risk: for overall EC, for type-I EC, and in never smokers and never users of oral contraceptives (OCs). Smoking is a source of acrylamide, and OC use is a protective factor for EC risk.

Methods:

Cox regression was used to estimate hazard ratios (HRs) for the association between acrylamide intake and EC risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Acrylamide intake was estimated from the EU acrylamide monitoring database, which was matched with EPIC questionnaire-based food consumption data. Acrylamide intake was energy adjusted using the residual method.

Results:

No associations were observed between acrylamide intake and overall EC (n=1382) or type-I EC risk (n=627). We observed increasing relative risks for type-I EC with increasing acrylamide intake among women who both never smoked and were non-users of OCs (HR_Q5vsQ1: 1.97, 95% CI: 1.08–3.62; likelihood ratio test (LRT) P-value: 0.01, n=203).

Conclusions:

Dietary intake of acrylamide was not associated with overall or type-I EC risk; however, positive associations with type I were observed in women who were both non-users of OCs and never smokers.     

Lung cancer risks in relation to vegetable and fruit consumption and smoking

In a case-control study on lung cancer, risk was analysed in relation to smoking habits and frequency of vegetable and fruit consumption. Lung cancer cases in West Sweden and population controls were interviewed using a questionnaire where the frequency of consumption of dietary items and smoking habits were assessed. The material presented comprises 177 female and 359 male confirmed cases of lung cancer and 916 population controls. There was a dose-response relationship in regard to the number of cigarettes smoked and the number of years smoked, the latter factor being more important. After adjustment for number of cigarettes smoked/day and number of years smoked, the risk for those who seldom consumed vegetables was about twice of that among those who consumed vegetables frequently, both among nonsmokers, smokers and former smokers. This risk increase in relation to vegetable consumption also was present for different smoking categories. A similar tendency, although less pronounced, was found for fruit consumption. The results demonstrate that dietary factors are related to the risk for lung cancer, although smoking is the dominant risk factor.     

Dietary carotenoids,vegetables, and lung cancer risk in women: the Missouri women's health study (United States)

Objective: To examine the effect of specific dietary carotenoids and their primary plant food sources on lung cancer risk in a population-based case–control study of women. Methods: Data were available for 587 incident primary lung cancer cases and 624 controls frequency matched to cases based on age. A modified version of the 100-item NCI-Block food-frequency questionnaire was used to obtain information concerning usual diet 2–3 years prior to interview. Results: In models adjusted for age, total calorie intake, pack-years of smoking, and education, -carotene, -cryptoxanthin, lutein + zeaxanthin, and total carotenoid intake were each associated with a significantly lower risk of lung cancer. Several vegetable groups were predictive of lower lung cancer risk, particularly the frequency of total vegetable intake. Individual and total carotenoids were no longer significantly associated with lower lung cancer risk in models adjusted for total vegetable intake. However, total vegetable intake remained significantly inversely associated with risk in models adjusted for total carotenoids. Conclusions: These results indicate that consumption of a wide variety of vegetables has a greater bearing on lung cancer risk in a population of smoking and nonsmoking women than intake of any specific carotenoid or total carotenoids.     

Role of Household Exposure,Dietary Habits and Glutathione S-Transferases M1, T1 Polymorphisms in Susceptibility to Lung Cancer among Women in Mizoram India

Background: A case-control study was conducted to evaluate the effect of household exposure, dietary habits,smoking and Glutathione S-Transferases M1, T1 polymorphisms on lung cancer among women in Mizoram, India.Materials and Methods: We selected 230 newly diagnosed primary lung cases and 460 controls from women inMizoram. Multivariate logistic regression analysis was performed to estimate adjusted odds ratio (OR). Results:Exposure of cooking oil fumes (p<0.003), wood as heating source for cooking (p=0.004), kitchen inside livingroom (p=0.001), improper ventilated house (p=0.003), roasting of soda in kitchen (p=0.001), current smokers oftobacco (p=0.043), intake of smoked fish (p=0.006), smoked meat (p=0.001), Soda (p<0.001) and GSTM1 nullgenotype (p=0.003) were significantly associated with increased risk of lung cancer among women in Mizoram.Significantly protective effect was observed for intake of bamboo shoots (p=<0.001) and egg (p<0.001). A clearincrease in dose response gradient was observed for total cooking dish years. Risk for lung cancer tends to increasewith collegial effect of indoor environmental sources (p=0.022). Significant correlation was also observed forinteraction of GST polymorphisms with some of dietary habits. Conclusions: We confirmed the important roleof exposure of cooking oil emission and wood smoke, intake of smoked meat, smoked fish and soda (an alkalipreparation used as food additives in Mizoram) and tobacco consumption for increase risk of lung cancer amongWomen in Mizoram.     

Caffeine, alcohol, smoking, and the risk of incident epithelial ovarian cancer

BACKGROUND: Smoking, caffeine, and alcohol intake are all potentially modifiable factors that have an unclear association with ovarian cancer risk. Therefore, the associations between these exposures and ovarian cancer risk were prospectively examined among 110,454 women in the Nurses' Health Study (NHS) for the smoking analyses and 80,253 women for the dietary analyses. METHODS: Women completed biennial questionnaires assessing ovarian cancer risk factors beginning in 1976, with food frequency questionnaires administered every 2 to 4 years starting in 1980. For the smoking analyses, 737 confirmed cases of epithelial ovarian cancer were identified and for the dietary aims, 507 cases were identified through June 1, 2004. RESULTS: Compared with never-smokers, neither current nor past smoking was associated with ovarian cancer risk overall; however, both were associated with mucinous tumors (n = 69; rate ratio [RR], past = 2.02 [95% confidence interval (CI), 1.15-3.55]; RR, current = 2.22 [95% CI, 1.16-4.24]). A modest inverse association between caffeine intake and ovarian cancer risk was observed (RR, top vs bottom quintile = 0.80; 95% CI, 0.60-1.07 [P = .03]), which was strongest for women who had never used either oral contraceptives (RR = 0.65; 95% CI, 0.46-0.92 [P for heterogeneity = .02]) or postmenopausal hormones (RR = 0.57; 95% CI, 0.36-0.91 [P for heterogeneity = .13]). Alcohol was not associated with ovarian cancer risk. CONCLUSIONS: The results of the current study suggest that cigarette smoking may only increase the risk for mucinous ovarian tumors, and alcohol intake was not associated with risk. However, an inverse association was observed between caffeine intake and ovarian cancer risk, particularly in women not using hormones; this finding merits further study.     

A case-control study of stomach cancer and its relation to diet,cigarettes, and alcohol consumption in Saitama Prefecture,Japan

A case-control study of stomach cancer in relation to dietary, smoking, and drinking habits was undertaken in Saitama Prefectur, Japan. The study was based on 294 cases of newly diagnosed adenocarcinoma of the stomach at a single institution, 294 general population controls (matched by sex, age, and administrative division), and 202 hospital controls. Dietary habits were investigated based on the intake of 12 separate foods and 12 food groups in a food frequency questionnaire, together with individual food preferences. The consumption of raw vegetables was inversely related to the risk of stomach cancer, with a dose-response relation observed consistently in the comparisons with both sets of controls. Current cigarette smokers (1–29/day) had an increased risk (relative risk = 1.8,95 percent confidence interval = 1.1–3.0) compared with nonsmokers in the general population controls, but no dose-response effect with heavier cigarette smoking. Alcohol use did not affect the risk of stomach cancer. In the multiple logistic regression, the comsumption of raw vegetables showed a protective effect on stomach cancer while cigarette smoking had no significant association, in both sets of controls.Drs Hoshiyama and Sasaba are in the Department of Epidemiology, Saitama Cancer Center Research Institute, Japan. Address correspondence to Dr Hoshiyama, Komuro 818, Ina, Saitama 362, Japan.     

Dietary intake of fruit and vegetable and lung cancer risk: a case-control study in Harbin, northeast China.

BACKGROUND: We studied the relationship between dietary intake of vegetables and fruit and lung cancer risk in Harbin, Heilongjiang province, northeast China, an area with a very high baseline risk of lung cancer in both sexes. PATIENTS AND METHODS: We used data from a case-control study, conducted from 1987 to 1990, among 218 cases with incident, histologically confirmed lung cancer and 436 controls admitted to the same hospitals as cases with non-neoplastic, non-lung diseases unrelated to smoking and other potential risk factors for lung cancer. RESULTS: Compared with the lowest tertile of intake of vegetables, fruit or both, the multivariate odds ratios (ORs) for the highest tertile of intake were 0.39 [95% confidence interval (CI) 0.25-0.62], 0.73 (95% CI 0.48-1.11) and 0.40 (95% CI 0.25-0.63), respectively. In particular, high intake of Chinese cabbage (OR = 0.53), chives (OR = 0 .54), carrots (OR = 0.51) and celery (OR = 0.40) was inversely associated with lung cancer. The OR was more than six-fold elevated for smokers reporting low intake of vegetables, and more than four-fold elevated for smokers reporting low intake of fruit, as compared with never smokers reporting high intake of these items. CONCLUSION: In agreement with previous studies, we found an inverse relation between vegetable and fruit intake and lung cancer risk in both strata of current and never smokers.     

Dietary factors and risk of lung cancer in never-smokers

We studied dietary risk factors for lung cancer among never-smokers in a population-based case–control study in Stockholm, 1989–1995. Study subjects were older than 30 years of age and had never smoked regularly. A total of 124 cases (35 men, 89 women) and 235 controls (72 men, 163 women) participated. Exposure information was obtained at interview with study subjects. The never-smoking status was validated by interviews with next-of-kin. A protective effect was suggested for vegetables, mediated primarily by carrots (relative risk [RR], 0.7; 95% confidence interval [CI], 0.4–1.3, and 0.6, 0.3–1.1 for intermediate and high consumption of carrots, respectively). Non-citrus fruits appeared to lower the risk as well, with RR 0.6, 95% CI 0.3–1.3 and 0.5, 0.3–1.0 for intermediate and high consumption, respectively. A protective effect with dose-response was also seen for intake of beta-carotene and total carotenoids. Increased risks were seen for cultured milk products in both genders (RR 2.0, 95% CI 1.1–3.9 for intermediate and 1.6, 0.9–2.9 for high consumption), but for milk only among male high consumers. Our results support evidence linking a diet rich in vegetables and non-citrus fruit with decreased lung cancer risk and suggests that among vegetables, carrot consumption is the most important component or marker for this effect in Sweden. The results regarding milk products could be consistent with dietary fat as a risk factor for lung cancer, although a more comprehensive assessment of fat intake is necessary to explore this relation. Int. J. Cancer 78:430–436, 1998. © 1998 Wiley-Liss, Inc.     

Environmental tobacco smoke and lung cancer risk in nonsmoking women.

BACKGROUND: Exposure to environmental tobacco smoke (passive smoking) has been suggested to be a cause of lung cancer, although early epidemiologic studies have produced inconsistent results. PURPOSE: We conducted an epidemiologic case-control study to assess the relationship between exposure to environmental tobacco smoke and lung cancer risk among women who have never smoked (i.e., having smoked for a total of less than 6 months or having smoked less than 100 cigarettes in their lifetimes). METHODS: Case patients (n = 210) were women with histologically confirmed primary carcinomas of the lung who were lifetime nonsmokers. They were identified through hospital tumor registries and the Florida Cancer Data System of the Statewide Cancer Registry. Community-based control women (n = 301) were also lifetime nonsmokers and were identified through random-digit dialing. Details on childhood and adulthood exposures to environmental tobacco smoke were ascertained through interviews with the study participants themselves or with surrogate respondents. Risks were calculated in terms of smoke-years, defined as the sum of the reported years of exposure to cigarette smoke from each smoker in the household. RESULTS: The risk of lung cancer more than doubled for women who reported 40 or more smoke-years of household exposure during adulthood (odds ratio [OR] = 2.4; 95% confidence interval [CI] = 1.1-5.3) or 22 or more smoke-years of exposure during childhood and adolescence (OR = 2.4; 95% CI = 1.1-5.4). Risks were highest for non-adenocarcinoma lung cancers, although modest elevations in risk were also observed for adenocarcinomas. When a surrogate respondent other than the patient's husband provided information on exposure, the risk estimates were considerably lower. CONCLUSION: These findings suggest that long-term exposure to environmental tobacco smoke increases the risk of lung cancer in women who have never smoked.     

Reproductive factors and risk of lung cancer in female textile workers in Shanghai, China

Purpose

Hormonal factors may play a role in the development of lung cancer in women. This study examined the relationship between lung cancer and reproductive factors in a large cohort of women, most of whom never smoked (97 %).

Methods

A cohort of 267,400 female textile workers in Shanghai, China, enrolled in a trial of breast self-examination provided information on reproductive history, demographical factors, and cigarette smoking at enrollment in 1989–91. The cohort was followed until July of 2000 for incidence of lung cancer; 824 cases were identified. Hazard ratios (HR) and 95 % confidence intervals (CI) associated with selected reproductive factors were calculated using Cox proportional hazards modeling, adjusting for smoking, age, and also parity when relevant.

Results

Nulliparous women were at increased risk compared to parous women (HR = 1.33, 95 % CI 1.00–1.77). Women who had gone through menopause at baseline were at increased risk compared to women of the same age who were still menstruating. Risk was higher in women with a surgical menopause (HR = 1.64, 95 % CI 0.96–2.79) than in those with a natural menopause (HR = 1.35, 95 % CI 0.84–2.18), and risk was highest in those postmenopausal women with a hysterectomy and bilateral oophorectomy at baseline (HR = 1.39, 95 % CI 0.96–2.00), although the risk estimates were not statistically significant.

Conclusions

These results support experimental data that demonstrate a biological role for hormones in lung carcinogenesis.     

Vitamin A and lung cancer.

Retrospective dietary and smoking data were gathered by interview of 292 white male patients with lung cancer and 801 control patients with nonrespiratory, nonneoplastic diseases at Roswell Park Memorial Institute, Buffalo, New York. A computed index of vitamin A intake was used to differentiate lung cancer patients from controls. Lung cancer patients had lower values than did controls. The reduced relative risk (RR) of lung cancer associated with vitamin A was most evident among men who smoked heavily. For them, a dose-response relationship increasing to an RR of 2.4 for low values of the index was observed. Frequency of daily milk drinking was lower among patients with lung cancer. Lower RR was found among the men who smoked heavily and frequently consumed carrots. These findings are consistent with evidence from animal studies on inhibition of tumor incidence by retinoids and with previous findings in prospective and retrospective epidemiologic studies.     

Cigarette smoking, alcohol intake, and thyroid cancer risk: a pooled analysis of five prospective studies in the United States

Objective

We examined the associations between cigarette smoking, alcohol intake, and thyroid cancer risk in a pooled analysis of five prospective studies.

Methods

Data from five prospective U.S. studies were standardized and then combined into one aggregate dataset (384,433 men and 361,664 women). Pooled hazard ratios (HR) and 95?% confidence intervals (CI) for thyroid cancer were estimated from mutually adjusted models of cigarette smoking and alcohol intake, which were additionally adjusted for age, sex, education, race, marital status, body mass index, and cohort.

Results

Over follow-up, 1,003 incident thyroid cancer cases (335 men and 668 women) were identified. Compared to never smokers, current smoking was associated with reduced risk of thyroid cancer (HR?=?0.68, 95?% CI 0.55–0.85); this association was slightly stronger among non-drinkers (HR?=?0.46, 95?% CI 0.29–0.74). No reduction in risk was observed for former, compared to never, smokers. Greater smoking intensity, duration, and pack-years were associated with further reductions in risk among former and current smokers. Alcohol intake was also inversely associated with thyroid cancer risk (≥7 drinks/week versus 0, HR?=?0.72, 95?% CI 0.58–0.90, p trend?=?0.002). Inverse associations with smoking and alcohol were more pronounced for papillary versus follicular tumors.

Conclusion

The results of this pooled analysis suggest that both cigarette smoking and alcohol consumption are associated with reduced risks of papillary thyroid cancer and, possibly, follicular thyroid cancer.     

A prospective study of NAT2 acetylation genotype, cigarette smoking, and risk of breast cancer

Polymorphisms in the N-acetyltransferase 2 (NAT2) gene are determinants of the rate of metabolic activation of carcinogenic compounds such as aryl aromatic amines. Homozygosity for any combination of three variant alleles in Caucasians defines 'slow' acetylators; presence of one or two wild-type alleles characterizes 'rapid' acetylators. Although most previous studies have not observed an overall elevation in risk of breast cancer among slow acetylators, a recent study observed that cigarette smoking was associated with a large increase in risk of breast cancer among slow acetylators. We assessed the relation between NAT2 acetylation status and breast cancer risk, and its interaction with smoking, in a prospective study of mainly Caucasian US women. Four hundred and sixty-six incident cases who were diagnosed with breast cancer after giving a blood specimen in 1989-90 were matched to 466 controls in a nested case-control study. NAT2 genotype was determined using PCR-RFLP assays. The multivariate relative risk (RR) comparing slow with rapid acetylators was 0.9 (95% CI 0.7-1.2). Among slow acetylators, current smoking immediately prior to diagnosis was not associated with a significant elevation in risk compared with never smoking rapid acetylators (RR = 1.4, 95% CI 0.7-2.6). No significant association was seen between pack-years of smoking and risk of breast cancer among either slow or fast acetylators. A non-significant elevation in risk was observed among women who smoked for > or = 5 years prior to first pregnancy and were rapid acetylators, compared with never smoking rapid acetylators (RR = 1.5, 95% CI 0.9-2.6). In analyses limited to 706 post-menopausal women, the elevated risks for current smokers immediately prior to diagnosis who were slow acetylators compared with never smokers who were fast acetylators were slightly stronger but still not statistically significant. In summary, we observed little evidence of an association between NAT2 genotype and breast cancer. In this prospective study, cigarette smoking was not appreciably associated with breast cancer among either slow or fast NAT2 acetylators.      

Prospective study of fruit and vegetable consumption and risk of lung cancer among men and women

BACKGROUND: Diets high in fruits and vegetables have been shown to be associated with a lower risk of lung cancer. beta-Carotene was hypothesized to be largely responsible for the apparent protective effect, but this hypothesis was not supported by clinical trials. METHODS: We examined the association between lung cancer risk and fruit and vegetable consumption in 77 283 women in the Nurses' Health Study and 47 778 men in the Health Professionals' Follow-up Study. Diet was assessed with the use of a food-frequency questionnaire that included 15 fruits and 23 vegetables. We used logistic regression models to estimate relative risks (RRs) of lung cancer within each cohort. All statistical tests were two-sided. RESULTS: We documented 519 lung cancer cases among the women and 274 among the men. Total fruit and vegetable consumption was associated with a modestly lower risk of lung cancer among the women but not among the men. The RR for the highest versus lowest quintile of intake was 0.79 (95% confidence interval [CI] = 0.59-1.06) among the women and 1.12 (95% CI = 0.74-1.69) among the men after adjustment for smoking status, quantity of cigarettes smoked per day, time since quitting smoking, and age at initiation of smoking. However, total fruit and vegetable consumption was associated with a lower risk of lung cancer among never smokers in the combined cohorts, although the reduction was not statistically significant (RR = 0.63; 95% CI = 0.35-1.12 in the highest tertile). CONCLUSION: Higher fruit and vegetable intakes were associated with lower risks of lung cancer in women but not in men. It is possible that the inverse association among the women remained confounded by unmeasured smoking characteristics, although fruits and vegetables were protective in both men and women who never smoked.     

Smoking duration before first childbirth: an emerging risk factor for breast cancer? Results from 302,865 Norwegian women

Purpose

Recently, The International Agency for Research on Cancer classified cigarette smoking as possibly carcinogenic to the human breast. Since some new cohort studies have suggested that this risk is confined to women who started to smoke before first childbirth, we wanted to examine the association between smoking and breast cancer, with a focus on time of smoking initiation in relation to the first childbirth.

Methods

We followed 302,865 Norwegian women born between 1899 and 1975, recruited from 1974 to 2003, by linkage to national registries through December 2007. We used Cox proportional hazard models to estimate hazard ratios (HR) and 95 % confidence intervals (CI).

Results

During more than 4.1 million person-years of follow-up, we ascertained 7,490 cases of primary invasive breast cancer. Compared with never smokers, ever smokers had a 15 % (HR = 1.15, 95 % CI 1.10–1.21) increased risk of breast cancer overall and also a significantly increased risk of breast cancer in the three most exposed categories of age at smoking initiation (parous women), number of cigarettes smoked per day, years of smoking duration and number of pack-years. Ever smokers who started to smoke more than 1 year after the first childbirth had not an increased risk (HR = 0.93, 95 % CI 0.86–1.02), while those who initiated smoking more than 10 years before their first childbirth had a 60 % (HR = 1.60, 95 % CI 1.42–1.80) increased risk of breast cancer, compared with never smokers.

Conclusion

Smoking initiation before the first childbirth increases the risk of breast cancer.     

Salt intake and gastric cancer risk according to Helicobacter pylori infection, smoking, tumour site and histological type

Background:

Although salt intake is considered a probable risk factor for gastric cancer, relevant studies have provided heterogeneous results, and the magnitude of the association has not been accurately quantified.

Methods:

To quantify gastric cancer risk in relation to dietary salt exposure according to Helicobacter pylori infection status and virulence, smoking, tumour site, and histological type, we evaluated 422 gastric cancer cases and 649 community controls. Salt exposure was estimated in the year before the onset of symptoms through: sodium intake (estimated by a food frequency questionnaire (FFQ)); main food items/groups contributing to dietary sodium intake; visual analogical scale for salt intake preference; use of table salt; and duration of refrigerator ownership.

Results:

Comparing subjects with the highest with those with the lowest salt exposure (3rd vs 1st third), sodium intake (OR=2.01, 95% CI: 1.16–3.46), consumption of food items with high contribution to sodium intake (OR=2.54, 95% CI: 1.56–4.14) and salt intake evaluated by visual analogical scale (OR=1.83, 95% CI: 1.28–2.63) were associated with an increased gastric cancer risk. Subjects owning a refrigerator for >50 years had a lower risk for gastric cancer (OR=0.28, 95% CI: 0.14–0.57). These associations were observed regardless of H. pylori infection status and virulence, smoking, tumour site or histological type.

Conclusion:

Our results support the view that salt intake is an important dietary risk factor for gastric cancer, and confirms the evidence of no differences in risk according to H. pylori infection and virulence, smoking, tumour site and histological type.     

Dietary cryptoxanthin and reduced risk of lung cancer: the Singapore Chinese Health Study.

High prediagnostic serum beta-cryptoxanthin levels have been found to be associated with reduced risk of lung cancer in a recent cohort study of Chinese men in Shanghai, China. Data on dietary beta-cryptoxanthin, and other specific carotenoids and antioxidants in relation to lung cancer, particularly in non-Western populations, are scarce. The aim of the present study was to assess the roles of dietary antioxidants in the development of lung cancer. Between April 1993 and December 1998, 63,257 Chinese men and women ages 45-74 years in Singapore participated in a prospective study of diet and cancer. At baseline, an in-person interview was conducted using a structured questionnaire for information on usual dietary habits, tobacco smoking, and other lifestyle factors. A Singapore food composition database was used to estimate intake of alpha-carotene, beta-carotene, beta-cryptoxanthin, lycopene, lutein/zeaxanthin, vitamins A, C, and E, and folate in study subjects. During the first 8 years of follow-up, 482 lung cancer cases occurred among cohort members. High levels of dietary beta-cryptoxanthin were associated with reduced risk of lung cancer; relative to the lowest quintile, the self-reported smoking adjusted relative risks (95% confidence intervals) for the highest quintile were 0.73 (0.54-0.98) among all of the subjects and 0.63 (0.41-0.99) among current smokers. Before adjustment for cigarette smoking, dietary vitamin C was associated with a statistically significant reduction in risk of lung cancer. However the inverse vitamin C-lung cancer association was largely explained by smoking and dietary beta-cryptoxanthin. Other carotenoids (alpha-carotene, beta-carotene, lycopene, and lutein/zeaxanthin), vitamins A and E, and folate were not associated significantly with lung cancer risk after adjustment for cigarette smoking. We recognized that potential measurement errors in cigarette smoking may exert an effect on the dietary beta-cryptoxanthin-lung cancer association. After additional adjustments were made for the residual confounding by smoking using statistical models, about 15-40% reduction in risk of lung cancer was seen for subjects in the highest versus lowest 10th percentile of dietary beta-cryptoxanthin. The present study lends additional credence to prior experimental and epidemiological data in support of the hypothesis that dietary beta-cryptoxanthin is a chemopreventive agent for lung cancer in humans.     

Cigarette smoking and colorectal cancer mortality in the cancer prevention study II

BACKGROUND: Recent studies suggest that long-term cigarette smoking is associated with an increased risk of colorectal cancer. Whether the association is causal or due to confounding remains unclear. METHODS: We examined cigarette smoking in relation to colorectal cancer mortality, evaluating smoking duration and recency and controlling for potential confounders in the Cancer Prevention Study II. This prospective nationwide mortality study of 1 184 657 adults (age > or =30 years) was begun by the American Cancer Society in 1982. After exclusions, our analytic cohort included 312 332 men and 469 019 women, among whom 4432 colon or rectal cancer deaths occurred between 1982 and 1996 among individuals who were cancer free in 1982. Rate ratios (RRs) and 95% confidence intervals (CIs) were estimated by fitting Cox proportional hazards models. All statistical tests were two-sided. RESULTS: Multivariate-adjusted colorectal cancer mortality rates were highest among current smokers, were intermediate among former smokers, and were lowest in lifelong nonsmokers. The multivariate-adjusted RR (95% CI) for current compared with never smokers was 1.32 (1.16-1.49) among men and 1.41 (1.26-1.58) among women. Increased risk was evident after 20 or more years of smoking for men and women combined as compared with never smokers. Risk among current and former smokers increased with duration of smoking and average number of cigarettes smoked per day; risk in former smokers decreased significantly with years since quitting. If the multivariate-adjusted RR estimates in this study do, in fact, reflect causality, then approximately 12% of colorectal cancer deaths among both men and women in the general U.S. population in 1997 were attributable to smoking. CONCLUSIONS: Long-term cigarette smoking is associated with increased risk of colorectal cancer mortality in both men and women. Clear reduction in risk is observed with early smoking cessation.