Vitamin C, vitamin E, and multivitamin supplement use and stomach cancer mortality in the Cancer Prevention Study II cohort.

Supplementation with antioxidant vitamins has been associated with decreased risk of stomach cancer or regression of precancerous lesions in high-risk areas of China and Colombia. We examined the association between stomach cancer mortality and regular use (> or =15 times per month) of individual vitamin C supplements, individual vitamin E supplements, and multivitamins among 1,045,923 United States adults in the Cancer Prevention Study II (CPS-II) cohort. CPS-II participants completed a questionnaire at enrollment in 1982 and were followed for mortality through 1998. During follow-up, there were 1,725 stomach cancer deaths (1,127 in men and 598 in women). After adjustment for multiple potential stomach cancer risk factors, vitamin C use at enrollment was associated with reduced risk of stomach cancer mortality [rate ratio (RR), 0.83; 95% confidence interval (CI), 0.68-1.01]. However, this reduction in risk was observed only among participants with short duration use at enrollment (RR, 0.68; 95% CI, 0.51-0.91 for <10 years of use; RR, 1.00; 95% CI, 0.73-1.38 for > or =10 years of use). There was no association between stomach cancer mortality and regular use of vitamin E (RR, 1.02; 95% CI, 0.82-1.27) or multivitamins (RR, 0.89; 95% CI, 0.77-1.03), regardless of duration of use. Our results suggest that the use of vitamin C, vitamin E, or multivitamin supplements may not substantially reduce risk of stomach cancer mortality in North American populations in which stomach cancer rates are relatively low. Our results do not rule out effects of vitamin supplementation in areas in which stomach cancer rates are high and stomach cancer etiology may differ.     

Vitamin or mineral supplement intake and the risk of head and neck cancer: pooled analysis in the INHANCE consortium

To investigate the potential role of vitamin or mineral supplementation on the risk of head and neck cancer (HNC), we analyzed individual-level pooled data from 12 case-control studies (7,002 HNC cases and 8,383 controls) participating in the International Head and Neck Cancer Epidemiology consortium. There were a total of 2,028 oral cavity cancer, 2,465 pharyngeal cancer, 874 unspecified oral/pharynx cancer, 1,329 laryngeal cancer and 306 overlapping HNC cases. Odds ratios (OR) and 95% confidence intervals (CIs) for self reported ever use of any vitamins, multivitamins, vitamin A, vitamin C, vitamin E, and calcium, beta-carotene, iron, selenium and zinc supplements were assessed. We further examined frequency, duration and cumulative exposure of each vitamin or mineral when possible and stratified by smoking and drinking status. All ORs were adjusted for age, sex, race/ethnicity, study center, education level, pack-years of smoking, frequency of alcohol drinking and fruit/vegetable intake. A decreased risk of HNC was observed with ever use of vitamin C (OR = 0.76, 95% CI = 0.59-0.96) and with ever use of calcium supplement (OR = 0.64, 95% CI = 0.42-0.97). The inverse association with HNC risk was also observed for 10 or more years of vitamin C use (OR = 0.72, 95% CI = 0.54-0.97) and more than 365 tablets of cumulative calcium intake (OR = 0.36, 95% CI = 0.16-0.83), but linear trends were not observed for the frequency or duration of any supplement intake. We did not observe any strong associations between vitamin or mineral supplement intake and the risk of HNC.     

Postdiagnosis supplement use and breast cancer prognosis in the After Breast Cancer Pooling Project

Vitamin supplement use after breast cancer diagnosis is common, but little is known about long-term effects on recurrence and survival. We examined postdiagnosis supplement use and risk of death or recurrence in the After Breast Cancer Pooling Project, a consortium of four cohorts of 12,019 breast cancer survivors from the United States and China. Post-treatment supplement use (vitamins A, B, C, D, E, and multivitamins) was assessed 1–5 years postdiagnosis. Associations with risk of recurrence, breast cancer-specific mortality, or total mortality were analyzed in Cox proportional hazards models separately by cohort. Individual cohort results were combined using random effects meta-analysis. Interactions with smoking, treatment, and hormonal status were examined. In multivariate models, vitamin E was associated with a decreased risk of recurrence (RR: 0.88; 95 % CI 0.79–0.99), and vitamin C with decreased risk of death (RR: 0.81; 95 % CI 0.72–0.92). However, when supplements were mutually adjusted, all associations were attenuated. There were no statistically significant associations with breast cancer mortality. The use of antioxidant supplements (multivitamins, vitamin C, or E) was not associated with recurrence, but was associated with a 16 % decreased risk of death (95 % CI 0.72–0.99). In addition, vitamin D was associated with decreased risk of recurrence among ER positive, but not ER negative tumors (p-interaction = 0.01). In this large consortium of breast cancer survivors, post-treatment use of vitamin supplements was not associated with increased risk of recurrence or death. Post-treatment use of antioxidant supplements was associated with improved survival, but the associations with individual supplement were difficult to determine. Stratification by ER status and considering antioxidants as a group may be more clinically relevant when evaluating associations with cancer risk and mortality.     

Vitamin supplement use and risk for breast cancer: the Shanghai Breast Cancer Study

Objective The influence of vitamin supplements on breast cancer risk is unclear and the interactive effects of dietary and supplemental sources are unknown. This study investigated (1) the association between self-reported vitamin supplement use (multivitamin, A, B, C, and E) and breast cancer and (2) the combined effect of vitamin supplements in relation to dietary vitamin intakes on breast cancer risk. Methods The Shanghai Breast Cancer Study was a population-based case-control study conducted in Shanghai in 1996-1998 (Phase I) and 2002-2004 (Phase II). Participants were aged 25-64 (Phase I) and 20-70 years (Phase II). The analyses included 3,454 incident breast cancer cases and 3,474 controls. Unconditional logistic regression models were used to determine adjusted odds ratios (ORs) for breast cancer risk associated with vitamin supplement use. Results Overall, breast cancer risk was not related to any vitamin supplement intake. However, a 20% reduction in breast cancer risk was observed with vitamin E supplement use among women with low-dietary vitamin E intake (OR = 0.8; 95% confidence interval (CI), 0.6-1.0). A non-significant 20% risk reduction was observed among vitamin B supplement users with low B dietary intake (OR = 0.8; 95% CI, 0.6-1.1). Frequent use of a vitamin B supplement was adversely associated with breast cancer risk among those with high dietary vitamin B intake (OR = 1.4; 95% CI: 0.9-2.1; P for interaction = 0.07). Conclusions This study suggests that vitamins E and B supplements may confer protection against breast cancer among women who have low dietary intake of those vitamins.     

Antioxidant supplement use after breast cancer diagnosis and mortality in the Life After Cancer Epidemiology (LACE) cohort

BACKGROUND:

There is concern that antioxidant supplement use during chemotherapy and radiation therapy may decrease treatment effects, yet the effects of such supplements on recurrence and survival are largely unknown.

METHODS:

The authors prospectively examined the associations between antioxidant use after breast cancer (BC) diagnosis and BC outcomes in 2264 women in the Life After Cancer Epidemiology (LACE) cohort. The cohort included women who were diagnosed with early stage, primary BC from 1997 to 2000 who enrolled, on average, 2 years postdiagnosis. Baseline data were collected on antioxidant supplement use since diagnosis and other factors. BC recurrence and mortality were ascertained, and hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using delayed entry Cox proportional hazards models. All tests of statistical significance were 2‐sided.

RESULTS:

Antioxidant supplement use after diagnosis was reported by 81% of women. Among antioxidant users, frequent use of vitamin C and vitamin E was associated with a decreased risk of BC recurrence (vitamin C: HR, 0.73; 95% CI, 0.55‐0.97; vitamin E: HR, 0.71; 95% CI, 0.54‐0.94); and vitamin E use was associated with a decreased risk of all‐cause mortality (HR, 0.76; 95% CI, 0.58‐1.00). Conversely, frequent use of combination carotenoids was associated with increased risk of death from BC (HR, 2.07; 95% CI, 1.21‐3.56) and all‐cause mortality (HR, 1.75; 95% CI, 1.13‐2.71).

CONCLUSIONS:

Frequent use of vitamin C and vitamin E in the period after BC diagnosis was associated with a decreased likelihood of recurrence, whereas frequent use of combination carotenoids was associated with increased mortality. The effects of antioxidant supplement use after diagnosis likely differ by type of antioxidant. Cancer 2012. © 2011 American Cancer Society.     

Dietary supplement use and colorectal cancer risk: A systematic review and meta‐analyses of prospective cohort studies

Use of dietary supplements is rising in countries where colorectal cancer is prevalent. We conducted a systematic literature review and meta‐analyses of prospective cohort studies on dietary supplement use and colorectal cancer risk. We identified relevant studies in Medline, Embase and Cochrane up to January 2013. Original and peer‐reviewed papers on dietary supplement use and colorectal cancer, colon cancer, or rectal cancer incidence were included. “Use‐no use”(U‐NU), “highest‐lowest”(H‐L) and “dose‐response”(DR) meta‐analyses were performed. Random‐effects models were used to estimate summary estimates. In total, 24 papers were included in the meta‐analyses. We observed inverse associations for colorectal cancer risk and multivitamin (U‐NU: RR = 0.92; 95% CI: 0.87,0.97) and calcium supplements (U‐NU: RR = 0.86; 95% CI: 0.79,0.95; H‐L: RR = 0.80; 95% CI: 0.70,0.92; DR: for an increase of 100 mg/day, RR = 0.96; 95% CI: 0.94,0.99). Inconsistent associations were found for colon cancer risk and supplemental vitamin A and vitamin C, and for colorectal cancer risk and supplemental vitamin D, vitamin E, garlic and folic acid. Meta‐analyses of observational studies suggest a beneficial role for multivitamins and calcium supplements on colorectal cancer risk, while the association with other supplements and colorectal cancer risk is inconsistent. Residual confounding of lifestyle factors might be present. Before recommendations can be made, an extensive assessment of dietary supplement use and a better understanding of underlying mechanisms is needed.     

Intakes of vitamins A, C and E and folate and multivitamins and lung cancer: a pooled analysis of 8 prospective studies

Intakes of vitamins A, C and E and folate have been hypothesized to reduce lung cancer risk. We examined these associations in a pooled analysis of the primary data from 8 prospective studies from North America and Europe. Baseline vitamin intake was assessed using a validated food-frequency questionnaire, in each study. We calculated study-specific associations and pooled them using a random-effects model. During follow-up of 430,281 persons over a maximum of 6-16 years in the studies, 3,206 incident lung cancer cases were documented. Vitamin intakes were inversely associated with lung cancer risk in age-adjusted analyses; the associations were greatly attenuated after adjusting for smoking and other risk factors for lung cancer. The pooled multivariate relative risks, comparing the highest vs. lowest quintile of intake from food-only, were 0.96 (95% confidence interval (CI) 0.83-1.11) for vitamin A, 0.80 (95% CI 0.71-0.91) for vitamin C, 0.86 (95% CI 0.76-0.99) for vitamin E and 0.88 (95% CI 0.74-1.04) for folate. The association with vitamin C was not independent of our previously reported inverse association with beta-cryptoxanthin. Further, vitamin intakes from foods plus supplements were not associated with a reduced risk of lung cancer in multivariate analyses, and use of multivitamins and specific vitamin supplements was not significantly associated with lung cancer risk. The results generally did not differ across studies or by sex, smoking habits and lung cancer cell type. In conclusion, these data do not support the hypothesis that intakes of vitamins A, C and E and folate reduce lung cancer risk.     

Vitamin E supplements and risk of prostate cancer in U.S. men.

Supplementation with alpha-tocopherol (a form of vitamin E) was associated with decreased risk of prostate cancer in a randomized trial among Finnish smokers. We examined the association between vitamin E supplement use and prostate cancer incidence in the Cancer Prevention Study II Nutrition Cohort. Participants in the study completed a detailed questionnaire at enrollment in 1992-1993. Historical information was also available from a questionnaire completed in 1982 at enrollment in a previous cohort. Through August 31, 1999, we documented 4,281 cases of incident prostate cancer among 72,704 men. Multivariate-adjusted rate ratios (RRs) were calculated using Cox Proportional Hazards models. Regular vitamin E supplement use (>/=4 times per week) was not associated with overall risk of prostate cancer or with risk of advanced prostate cancer at diagnosis. No trend was seen with increasing dose of vitamin E. Men who reported regular vitamin E use in both 1982 and in 1992-1993 were not at lower risk of prostate cancer. Among current smokers, there was a suggestion of slightly reduced risk with regular vitamin E supplement use [RR = 0.87, 95% confidence interval (CI) = 0.67-1.11]. Our results do not support an important role for vitamin E supplements in prostate cancer prevention.     

Evaluation of dietary, medical and lifestyle risk factors for incident kidney cancer in postmenopausal women

Kidney cancer incidence rates in the United States have been increasing and are not fully accounted for by better diagnostic techniques. Risk factors in women are incompletely described. A total of 34,637 Iowan women initially free of cancer completed a mailed questionnaire in 1986. Kidney cancer incidence was identified over 15 years of follow-up (n = 124) through linkage to a statewide cancer registry. Adjusted for age and other risk factors, kidney cancer was associated positively with maximum adult weight (p for trend = 0.02) and current waist-to-hip ratio (p for trend = 0.002). Compared to nondrinkers, consumers of alcohol of 3.0 or more grams per day had a relative risk (RR) of 0.52 (95% CI = 0.29-0.92). Total vitamin C intake was associated positively with risk of kidney cancer (p for trend = 0.04), whereas total vitamin E intake was associated negatively with risk (p for trend = 0.002). The few women who used copper supplements had a 6.52-fold increase in risk of kidney cancer (95% CI = 1.95-21.8). Compared to never users, women who were former users of estrogen had an increased risk of kidney cancer (RR = 1.62; 95% CI = 1.11-2.36), but current users of estrogen were not at a higher risk. Women who were nulliparous or had more than 2 live births were also at increased risk of kidney cancer compared with women who had 1 or 2 live births. In conclusion, in these postmenopausal women, overweight, particularly central adiposity, was an important risk factor for kidney cancer. Potential risk factors that warrant further exploration were low intake of alcohol and vitamin E, higher intake of vitamin C, nulli- or multiparity and use of copper supplements.     

Use of multivitamins and prostate cancer mortality in a large cohort of US men

Objective: To assess the association between the use of multivitamins and prostate cancer mortality.Methods: A total of 5585 deaths from prostate cancer were identified during 18 years of follow-up of 475,726 men who were cancer-free and provided complete information on multivitamin use at enrollment in the Cancer Prevention Study II (CPS-II) cohort in 1982. Cox proportional hazards modeling was used to measure the association between multivitamin use at baseline and death from prostate cancer and to adjust for potential confounders.Results: The death rate from prostate cancer was marginally higher among men who took multivitamins regularly (≥15 times/month) compared to non-users (multivariate rate ratio=1.07, 95% CI: 0.99–1.15); this risk was statistically significant only for those multivitamin users who used no additional (vitamin A, C, or E) supplements (multivariate rate ratio=1.15, 95% CI: 1.05–1.26). In addition, risk was greatest during the initial four years of follow-up (1982–1986, multivariate rate ratio=1.12, 95 CI: 0.87–1.46).Conclusions: Regular multivitamin use was associated with a small increase in prostate cancer death rates in our study, and this association was limited to a subgroup of users.     

Alcohol, physical activity and other risk factors for colorectal cancer: a prospective study

The aetiology of colorectal cancer was studied in a cohort of 11,888 residents of a retirement community. After four and one-half years of follow-up, 58 male and 68 female incident colorectal cancers were identified. Daily alcohol drinkers experienced nearly a two-fold increase in risk (2 sided P = 0.002). Colorectal cancer was also positively associated with Quetelet's index and inversely associated with avocational physical activity. The results were consistent for both sexes but were statistically significant only for males. With the exception of dietary vitamin C, none of the nutrients under study (i.e., vitamins A and E, dietary fibre, calcium, and beta carotene) showed a significant association with colorectal cancer. An inverse relationship between colorectal cancer and dietary vitamin C was observed in females, but there was no association with either vitamin C from supplements or with total vitamin C intake. Males and females who had 3 or more children showed a significantly reduced risk of colorectal cancer (RR = 0.45, 95% CI = 0.2, 0.9), but those with no children did not show the highest risk.     

Calcium from diet and supplements is associated with reduced risk of colorectal cancer in a prospective cohort of women.

We investigated the association between calcium intake and colorectal cancer in a prospective cohort of 45,354 women without a history of colorectal cancer who successfully completed a 62-item National Cancer Institute/Block food-frequency questionnaire. Women were followed for an average of 8.5 years, during which time 482 subjects developed colorectal cancer. We used Cox proportional hazards models, with age as the underlying time metric, to estimate risk of colorectal cancer. Cut points between quintiles of energy-adjusted dietary calcium were 412, 529, 656, and 831 mg/day. We created categories for calcium from supplements as follows: 0 mg/day (n = 25,441), 0 to 400 mg/day (n = 9,452), 401 to 800 mg/day (n = 4,176), and >800 mg/day (n =6,285). Risk ratios and confidence intervals (95% CI) for increasing quintiles of dietary calcium relative to the lowest quintile were 0.79 (0.60-1.04), 0.77 (0.59-1.02), 0.78 (0.60-1.03), and 0.74 (0.56-0.98), P(trend) = 0.05. For increasing categories of calcium from supplements, the risk ratios (and 95% CI) relative to no supplement use were 1.08 (0.87-1.34), 0.96 (0.70-1.32), and 0.76 (0.56-1.02), P(trend) = 0.09. Simultaneously high consumption of calcium from diet and calcium from supplements resulted in even further risk reduction, RR = 0.54 (95% CI, 0.37-0.79) compared with low consumption of both sources of calcium. These data indicate that a difference of < 400 to > 800 mg of calcium per day was associated with an approximately 25% reduction in risk of colorectal cancer, and this reduction in risk occurred regardless of the source of the calcium (i.e., diet or supplements).     

Risk of ovarian carcinoma and consumption of vitamins A, C, and E and specific carotenoids: a prospective analysis.

BACKGROUND: Antioxidant vitamins may decrease risk of cancer by limiting oxidative DNA damage leading to cancer initiation. Few prospective studies have assessed relations between antioxidant vitamins and ovarian carcinoma. METHODS: The authors prospectively assessed consumption of vitamins A, C, and E and specific carotenoids, as well as fruit and vegetable intake, in relation to ovarian carcinoma risk among 80,326 participants in the Nurses' Health Study who had no history of cancer other than nonmelanoma skin carcinoma. Women reported on known and suspected ovarian carcinoma risk factors including reproductive factors, smoking, and use of vitamin supplements on biennial mailed questionnaires from 1976 to 1996. Food frequency questionnaires were included in 1980, 1984, 1986, and 1990. The authors confirmed 301 incident cases of invasive epithelial ovarian carcinoma during 16 years of dietary follow-up (1980-1996). Pooled logistic regression was used to control for age, oral contraceptive use, body mass index, smoking history, parity, and tubal ligation. RESULTS: The authors observed no association between ovarian carcinoma risk and antioxidant vitamin consumption from foods, or foods and supplements together. The multivariate relative risks (95% confidence intervals [CIs]) for ovarian carcinoma among women in the highest versus lowest quintile of intake were 1.04 (95% CI, 0.72-1.51) for vitamin A from foods and supplements; 1.01 (95% CI, 0.69-1.47) for vitamin C; 0.88 (95% CI, 0.61-1.27) for vitamin E; and 1.10 (95% CI, 0.76-1.59) for beta-carotene. Among users of vitamin supplements, the authors found no evidence of an association between dose or duration of any specific vitamin and ovarian carcinoma risk, although the authors had limited power to assess these relations. No specific fruits or vegetables were associated significantly with ovarian carcinoma risk. The authors found no association between ovarian carcinoma and consumption of total fruits or vegetables, or specific subgroups including cruciferous vegetables, green leafy vegetables, legumes, or citrus fruits. Women who consumed at least 2.5 total servings of fruits and vegetables as adolescents had a 46% reduction in ovarian carcinoma risk (relative risk, 0.54, 95% CI, 0.29-1.03; P value for trend 0.04). CONCLUSIONS: These data do not support an important relation between consumption of antioxidant vitamins from foods or supplements, or intake of fruits and vegetables, and incidence of ovarian carcinoma in this cohort. However, modest associations cannot be excluded, and the authors' finding of an inverse association for total fruit and vegetable intake during adolescence raises the possibility that the pertinent exposure period may be much earlier than formerly anticipated.     

Vitamins C and E, retinol, beta-carotene and dietary fibre in relation to breast cancer risk: a prospective cohort study.

Association between breast cancer risk and the intake of vitamins C and E, retinol, beta (beta)-carotene, dietary fibre, vegetables, fruit and potatoes was examined in The Netherlands Cohort Study, for 62,573 women aged 55-69 years. After 4.3 years of follow-up, 650 incident breast cancer cases were identified. After adjusting for traditional risk factors, breast cancer risk was not influenced by the intake of beta-carotene, vitamin E, dietary fibre, supplements with vitamin C, vegetables or potatoes. Fruit consumption showed a non-significant inverse association with breast cancer risk (RR highest/lowest quintile = 0.76, 95% CI 0.54-1.08). A small reduction in risk was also observed with increasing intake of dietary vitamin C (RR highest/lowest quintile = 0.77, 95% CI 0.55-1.08). For retinol, a weak positive association was observed (RR highest/lowest quintile = 1.24, 95% CI 0.83-1.83). Among subjects with a high intake of polyunsaturated fatty acids (PUFAs), both beta-carotene and vitamin C intake showed a non-significant inverse association with breast cancer risk (P-trend = 0.15 and 0.16 respectively). Our findings do not suggest a strong role, if any, for intake of vitamins C and E, beta-carotene, retinol, dietary fibre, vegetables, fruit and potatoes in the aetiology of breast cancer.     

Vitamin and mineral use and risk of prostate cancer: the case–control surveillance study

Background  Many studies have evaluated the association between vitamin and mineral supplement use and the risk of prostate cancer, with inconclusive results. Methods  The authors examined the relation of use of multivitamins as well as several single vitamin and mineral supplements to the risk of prostate cancer risk among 1,706 prostate cancer cases and 2,404 matched controls using data from the hospital-based case–control surveillance study conducted in the United States. Odds ratios (OR) and 95% confidence intervals (CI) for risk of prostate cancer were estimated using conditional logistic regression model. Results  For use of multivitamins that did not contain zinc, the multivariable odds ratios of prostate cancer were 0.6 for 1–4 years, 0.8 for 5–9 years, and 1.2 for 10 years or more, respectively (p for trend = 0.70). Men who used zinc for ten years or more, either in a multivitamin or as a supplement, had an approximately two-fold (OR = 1.9, 95% CI: 1.0, 3.6) increased risk of prostate cancer. Vitamin E, beta-carotene, folate, and selenium use were not significantly associated with increased risk of prostate cancer. Conclusion  The finding that long-term zinc intake from multivitamins or single supplements was associated with a doubling in risk of prostate cancer adds to the growing evidence for an unfavorable effect of zinc on prostate cancer carcinogenesis.     

Supplemental vitamin E intake and prostate cancer risk in a large cohort of men in the United States.

A clinical trial of vitamin E and beta-carotene supplementation for lung cancer prevention among male smokers in Finland recently reported an unexpected, strong protective effect of vitamin E against prostate cancer incidence and mortality. Our objective was to prospectively examine supplemental vitamin E intake and prostate cancer risk in a distinct U.S. population. In 1986, we identified 47,780 U.S. male health professionals, free from diagnosed cancer, who completed a dietary and lifestyle questionnaire; supplemental vitamin E and prostate cancer incidence were updated biennially through 1996. We estimated relative risks (RRs) from multivariate pooled logistic regression models. There were 1896 total (non-stage A1), 522 extraprostatic, and 232 metastatic or fatal incident prostate cancer cases diagnosed between 1986-1996. Men consuming at least 100 IU of supplemental vitamin E daily had multivariate RRs of 1.07 (95% confidence interval [CI], 0.95-1.20) for total and 1.14 (95% CI, 0.82-1.59) for metastatic or fatal prostate cancer compared with those consuming none. Current use, dosage, and total duration of use of specific vitamin E supplements or multivitamins were not associated with risk. However, among current smokers and recent quitters, those who consumed at least 100 IU of supplemental vitamin E per day had a RR of 0.44 (95% CI, 0.18-1.07) for metastatic or fatal prostate cancer compared with nonusers. Thus, supplemental vitamin E was not associated with prostate cancer risk generally, but a suggestive inverse association between supplemental vitamin E and risk of metastatic or fatal prostate cancer among current smokers and recent quitters was consistent with the Finnish trial among smokers and warrants further investigation.     

Vitamin E intake and the lung cancer risk among female nonsmokers: A report from the Shanghai Women's Health Study

Vitamin E includes several tocopherol isoforms, which may reduce lung cancer risk, but past studies evaluating the association between vitamin E intake and lung cancer risk were inconsistent. We prospectively investigated the associations between tocopherol intake from diet and from supplements with lung cancer risk among 72,829 Chinese female nonsmokers aged 40–70 years and participating in the Shanghai Women's Health Study (SWHS). Dietary and supplement tocopherol exposure was assessed by a validated food‐frequency questionnaire at baseline and reassessed for change in intake during follow‐up. Cox proportional hazards models with time‐dependent covariates were used to calculate multivariate‐adjusted hazard ratios (HRs) and 95% confidence interval (CIs) for lung cancer. After 12.02 years of follow‐up, 481 women were diagnosed with lung cancer. Total dietary tocopherol was inversely associated with lung cancer risk among women meeting dietary guidelines for adequate intake (AI) of tocopherol (14 mg/day or more: HR: 0.78; 95% CI 0.60–0.99; compared with the category less than AI). The protective association between dietary tocopherol intake and lung cancer was restricted to women exposed to side‐stream smoke in the home and workplace [HR = 0.53 (0.29–0.97), p‐trend = 0.04]. In contrast, vitamin E supplement use was associated with increased lung cancer risk (HR: 1.33; 95% CI: 1.01–1.73), more so for lung adenocarcinoma risk (HR: 1.79; 95% CI: 1.23–2.60). In summary, dietary tocopherol intake may reduce the risk of lung cancer among female nonsmokers; however, supplements may increase lung adenocarcinoma risk and requires further investigation.     

Dietary carotenoids and vitamins A, C, and E and risk of breast cancer

BACKGROUND: Data on intake of specific carotenoids and breast cancer risk are limited. Furthermore, studies of vitamins A, C, and E in relation to breast cancer risk are inconclusive. We have conducted a large, prospective study to evaluate long-term intakes of these nutrients and breast cancer risk. METHODS: We examined, by use of multivariate analysis, associations between intakes of specific carotenoids, vitamins A, C, and E , consumption of fruits and vegetables, and breast cancer risk in a cohort of 83234 women (aged 33-60 years in 1980) who were participating in the Nurses' Health Study. Through 1994, we identified 2697 incident cases of invasive breast cancer (784 premenopausal and 1913 postmenopausal). RESULTS: Intakes of beta-carotene from food and supplements, lutein/zeaxanthin, and vitamin A from foods were weakly inversely associated with breast cancer risk in premenopausal women. Strong inverse associations were found for increasing quintiles of alpha-carotene, beta-carotene, lutein/zeaxanthin, total vitamin C from foods, and total vitamin A among premenopausal women with a positive family history of breast cancer. An inverse association was also found for increasing quintiles of beta-carotene among premenopausal women who consumed 15 g or more of alcohol per day. Premenopausal women who consumed five or more servings per day of fruits and vegetables had modestly lower risk of breast cancer than those who had less than two servings per day (relative risk [RR] = 0.77; 95% confidence interval [CI] = 0.58-1.02); this association was stronger among premenopausal women who had a positive family history of breast cancer (RR = 0.29; 95% CI = 0.13-0.62) or those who consumed 15 g or more of alcohol per day (RR = 0.53; 95% CI = 0.27-1.04). CONCLUSIONS: Consumption of fruits and vegetables high in specific carotenoids and vitamins may reduce premenopausal breast cancer risk.     

Prospective study of vitamins C, E, and A and carotenoids and risk of oral premalignant lesions in men

Case-control studies indicate that vitamins C, E, A and carotenoids decrease risk of oral premalignant lesions (OPLs) and oral cancer, but clinical trials have failed to find protective effects of beta-carotene and suggest that vitamin E may increase risk. The authors prospectively evaluated the association between intake of vitamins C, E, A and carotenoids and incidence of OPL. Participants were 42,340 men in the Health Professionals Follow-up Study who provided information on supplement use and diet every 2-4 years by food frequency questionnaire. The authors confirmed 207 clinically or histopathologically diagnosed OPL events occurring between 1986 and 2002 by medical record review. Multivariate-adjusted relative risks (RR) of OPL were calculated with proportional hazards models. Total intake of vitamin C, vitamin A or carotenoids was not significantly associated with OPL risk. Dietary vitamin C was significantly associated with reduced risk (quintile 5 vs. 1, RR = 0.52, 95% CI 0.31-0.85, p(trend) = 0.04), but no association with supplemental vitamin C was observed. Inverse associations were apparent for beta-cryptoxanthin and alpha-carotene intake. No clear relationship emerged with beta-carotene, lycopene or lutein/zeaxanthin. Vitamin E was associated with increased risk (quintile 5 vs. 1, RR = 1.86, 95% CI 1.06-3.19), particularly among current smokers and with supplemental intake (current-smokers, supplement dose tertile 3 vs. 1, RR = 3.07, 95% CI 1.28-7.34, p(trend) = 0.01). For current smokers, beta-carotene also increased risk. Vitamin C from dietary sources, but not supplements, was associated with a reduced risk of OPL. The observed increased risk for current smokers with high vitamin E or beta-carotene intake should be explored further.     

Calcium,vitamin D,dairy products,and risk of colorectal cancer in the Cancer Prevention Study II Nutrition Cohort (United States)

Objective: Calcium, vitamin D, and dairy product intake may reduce the risk of colorectal cancer. We therefore examined the association between these factors and risk of colorectal cancer in a large prospective cohort of United States men and women. Methods: Participants in the Cancer Prevention Study II Nutrition Cohort completed a detailed questionnaire on diet, medical history, and lifestyle in 1992–93. After excluding participants with a history of cancer or incomplete dietary information, 60,866 men and 66,883 women remained for analysis. During follow-up through 31 August 1997 we documented 421 and 262 cases of incident colorectal cancers among men and women, respectively. Multivariate-adjusted rate ratios (RR) were calculated using Cox proportional hazards models. Results: Total calcium intake (from diet and supplements) was associated with marginally lower colorectal cancer risk in men and women (RR = 0.87, 95% CI 0.67–1.12, highest vs lowest quintiles, p trend = 0.02). The association was strongest for calcium from supplements (RR = 0.69, 95% CI 0.49–0.96 for 500 mg/day vs none). Total vitamin D intake (from diet and multivitamins) was also inversely associated with risk of colorectal cancer, particularly among men (RR = 0.71, 95% CI 0.51–0.98, p trend = 0.02). Dairy product intake was not related to overall risk. Conclusions: Our results support the hypothesis that calcium modestly reduces risk of colorectal cancer. Vitamin D was associated with reduced risk of colorectal cancer only in men.