Prospective study of diet and ovarian cancer

Prospective investigation of poultry and fish intake in relation to cancer risk

Dietary guidelines advise consumers to limit intake of red meat and choose lean protein sources, such as poultry and fish. Poultry consumption has been steadily increasing in the United States, but the effect on cancer risk remains unclear. In a large U.S. cohort, we prospectively investigated poultry and fish intake and cancer risk across a range of malignancies in men and women. Diet was assessed at baseline (1995-1996) with a food frequency questionnaire in 492,186 participants of the NIH-AARP Diet and Health Study. Over a mean follow-up of 9 years, we identified 74,418 incident cancer cases. In multivariable Cox proportional hazards regression models, we estimated the substitution and addition effects of white meat (poultry and fish) intake in relation to cancer risk. In substitution models with total meat intake held constant, a 10-g (per 1,000 kcal) increase in white meat intake offset by an equal decrease in red meat intake was associated with a statistically significant reduced (3%-20%) risk of cancers of the esophagus, liver, colon, rectum, anus, lung, and pleura. In addition models with red meat intake held constant, poultry intake remained inversely associated with esophageal squamous cell carcinoma, liver cancer, and lung cancer, but we observed mixed findings for fish intake. As the dietary recommendations intend, the inverse association observed between white meat intake and cancer risk may be largely due to the substitution of red meat. Simply increasing fish or poultry intake, without reducing red meat intake, may be less beneficial for cancer prevention.

Folate and related micronutrients, folate-metabolising genes and risk of ovarian cancer

BACKGROUND/OBJECTIVE

Folates are essential for DNA synthesis and methylation, and thus may have a role in carcinogenesis. Limited evidence suggests folate-containing foods might protect against some cancers and may partially mitigate the increased risk of breast cancer associated with alcohol intake, but there is little information regarding ovarian cancer. Our aim was to evaluate the role of folate and related micronutrients, polymorphisms in key folate-metabolising genes and environmental factors in ovarian carcinogenesis.

SUBJECTS/METHODS

Participants in the Australian Ovarian Cancer Study (1363 cases, 1414 controls) self-completed risk factor and food-frequency questionnaires. DNA samples (1638 cases, 1278 controls) were genotyped for 49 tag single-nucleotide polymorphisms (SNPs) in the methylene tetrahydrofolate reductase (MTHFR), methionine synthase (MTR) and MTR reductase (MTRR) genes. Logistic regression models were used to generate adjusted odds ratios and 95% confidence intervals.

RESULTS

We saw no overall association between the intake of folate, B vitamins or other methyl donors and ovarian cancer risk, although increasing folate from foods was associated with reduced risk among current smokers (P(trend)=0.03) and folic acid intake was associated with borderline significant increased risks among women who consumed ≥1 standard alcoholic drinks/day (odds ratio (OR)=1.64; 95% confidence interval (CI) 1.05-2.54, P(trend)=0.05). Two SNPs (rs7365052, rs7526063) showed borderline significant inverse associations with ovarian cancer risk; both had very low minor allele frequencies. There was little evidence for interaction between genotype and micronutrient intake or for variation between different histological subtypes of ovarian cancer.

CONCLUSIONS

Our data provide little evidence to support a protective role for folate in ovarian carcinogenesis but suggest further evaluation of the joint effects of folic acid and alcohol is warranted.

Dietary cholesterol intake and cancer

BACKGROUND

This study assesses the association between dietary cholesterol intake and the risk of various cancers.

PATIENTS AND METHODS

Mailed questionnaires were completed between 1994 and 1997 in eight Canadian provinces by 1182 incident histologically confirmed cases of the stomach, 1727 of the colon, 1447 of the rectum, 628 of the pancreas, 3341 of the lung, 2362 of the breast, 442 of the ovary, 1799 of the prostate, 686 of the testis, 1345 of the kidney, 1029 of the bladder, 1009 of the brain, 1666 non-Hodgkin's lymphomas (NHL), 1069 leukemia and 5039 population controls. Information on dietary habits and nutrition intake were obtained using a food frequency questionnaire, which provided data on eating habits 2 years before the study. Odds ratios (ORs) were derived by unconditional logistic regression to adjust for total energy intake and other potential confounding factors.

RESULTS

Dietary cholesterol was positively associated with the risk of cancers of the stomach, colon, rectum, pancreas, lung, breast (mainly postmenopausal), kidney, bladder and NHL: the ORs for the highest versus the lowest quartile ranged from 1.4 to 1.7. In contrast, cholesterol intake was inversely associated with prostate cancer.

CONCLUSIONS

Our findings add to the evidence that high cholesterol intake is linked to increased risk of various cancers. A diet low in cholesterol may play a role in the prevention of several cancers.

Red and processed meat consumption and risk of ovarian cancer: a dose-response meta-analysis of prospective studies

Background:

During the last decade, the epidemiological evidence on consumption of meat and risk of ovarian cancer has accumulated.

Methods:

We assessed the relationship between red and processed meat consumption and risk of ovarian cancer with a dose-response meta-analysis. Relevant prospective cohort studies were identified by searching the PubMed and EMBASE databases through 21 January 2011, and by reviewing the reference lists of retrieved articles. Study-specific relative risk (RR) estimates were combined using a random-effects model.

Results:

Eight cohort studies were included in the meta-analysis. The summary RR for an intake increment of 100 g per week was 1.02 (95% confidence interval (CI), 0.99–1.04) for red meat and 1.05 (95% CI, 0.98–1.14) for processed meat. For an intake increment of four servings per week, the summary RR of ovarian cancer was 1.07 (95% CI, 0.97–1.19) for red meat (100 g per serving) and 1.07 (95% CI, 0.97–1.17) for processed meat (30 g per serving).

Conclusion:

Results from this dose-response meta-analysis suggest that red and processed meat consumption is not associated with risk of ovarian cancer. Although a lower consumption of red and processed meat may offer protection against other types of cancer, other interventions are needed to reduce the risk of ovarian cancer.

Consumption of dietary fat and meat and risk of ovarian cancer in the Netherlands Cohort Study

BACKGROUND

Evidence that links dietary factors to ovarian cancer is conflicting, but several epidemiologic studies suggested that consumption of dietary fat and meat may increase risk of ovarian cancer.

OBJECTIVE

We studied associations of intakes of total fat and sources and subtypes of fat, fresh meat, processed meat, and fish with ovarian cancer risk within the Netherlands Cohort Study (NLCS).

DESIGN

The NLCS includes 62,573 postmenopausal women, aged 55-69 y at baseline, who completed a baseline questionnaire on dietary habits and other risk factors for cancer in 1986. After 16.3 y of follow-up, 340 ovarian cancer cases and 2161 subcohort members were available for a case-cohort analysis. Multivariable rate ratios (RRs) were adjusted for age at baseline, total energy intake, oral contraceptive use, and parity.

RESULTS

There were no clear associations between intakes of total fat, saturated fat, mono- and polyunsaturated fats, animal fat, plant-based fat, dairy fat, other fat sources, fresh meat, processed meat, and fish and ovarian cancer risk. There was a positive association between consumption of trans unsaturated fatty acids and ovarian cancer risk. The multivariable RR for women in the highest compared with the lowest quintiles of intake was 1.51 (95% CI: 1.04, 2.20; P for trend = 0.01). Although no significant interactions by oral contraceptive use or parity were shown, effect sizes were generally more pronounced and significant in women who never used oral contraceptives and in parous women.

CONCLUSION

This prospective study suggests that trans unsaturated fatty acids, but no other types of fat or meat, are associated with increased ovarian cancer risk.

Carbohydrate intake, glycemic load, glycemic index, and risk of ovarian cancer

BACKGROUND

Our objective was to determine the relationship between dietary glycemic load (GL), glycemic index (GI), carbohydrate intake, and ovarian cancer risk in a population-based case-control study.

PATIENTS AND METHODS

A self-administered questionnaire was used to collect data on demographic and lifestyle factors, and a food frequency questionnaire was used to collect dietary information from 1366 women with ovarian cancer and 1414 population controls.

RESULTS

GL was positively associated with ovarian cancer. The adjusted odds ratio (OR) for the highest versus the lowest quartile of intake was 1.24 [95% confidence interval (CI) 1.00-1.55, P for trend = 0.03]. Fiber intake was inversely associated with risk. The OR comparing women in the highest fiber-intake group with those in the lowest was 0.78 (95% CI 0.62-0.98, P for trend = 0.11). We found no association between GI, carbohydrate intake, and ovarian cancer. In analyses stratified by body mass index, the risk estimates for GL, carbohydrate, and sugar were higher among overweight/obese women; however, the interaction term was only significant for sugar (P for interaction = 0.004).

CONCLUSIONS

Our results suggest that diets with a high GL may increase the risk of ovarian cancer, particularly among overweight/obese women, and a high intake of fiber may provide modest protection.

Association of lipid metabolism with ovarian cancer

Defects in lipid metabolism have been found to be linked to several diseases, among which atherosclerosis, hypertension, obesity, and diabetes are the most important. Although cancer is chiefly a genetic disease, dietary lipid intake and metabolism are related to some cancer risks, including the risk for ovarian cancer. Higher intake of dietary lipids, systemic lipid metabolism malfunction, and abnormal serum lipid levels are somehow related to ovarian cancer. Overexpression of some lipid metabolic enzymes are also found in ovarian cancer. In this review article, we summarize the relationships between lipid intake, lipid metabolism, and ovarian cancer.

A systematic literature review of vitamin D and ovarian cancer

OBJECTIVE

We assessed the evidence supporting a reduction in risk for ovarian cancer occurrence or mortality with greater vitamin D exposures.

STUDY DESIGN

This review followed standard guidelines for systematic literature reviews. The diverse study designs precluded a quantitative metaanalysis. Therefore studies are summarized via tables and abstracted information.

RESULTS

Approximately half of the ecologic and case-control studies reported reductions in incidence or mortality with increasing geographic latitude, solar radiation levels, or dietary/supplement consumption of vitamin D, whereas the other half reported null associations. The cohort studies reported no overall risk reduction with increasing dietary/supplement consumption of vitamin D or with plasma levels of vitamin D prior to diagnosis, although vitamin D intakes were relatively low in all studies.

CONCLUSION

There is no consistent or strong evidence to support the claim made in numerous review articles that vitamin D exposures reduce the risk for ovarian cancer occurrence or mortality.

Independent and joint effects of serum 25-hydroxyvitamin D and calcium on ovarian cancer risk: a prospective nested case-control study

INTRODUCTION

Ovarian cancer has very few known modifiable risk factors but dietary studies suggest a role for vitamin D and calcium in the prevention of ovarian cancer. Thus, we investigated the association between pre-diagnostic serum calcium and 25-hydroxyvitamin D (25-OHD) on the risk of later development of ovarian cancer.

METHODS

We conducted a population-based nested case-control study within the Finnish Maternity Cohort (FMC). The cohort subset comprised 172 ovarian cancer cases with 172 matched controls (age ± 1 year, parity and season of blood donation ± 2 weeks).

RESULTS

We observed a significant inverse association between calcium and ovarian cancer risk. Relative risk (estimated as odds ratio, OR) comparing the highest quartile to the lowest quartile was significantly decreased; 0.41 [95% confidence interval (CI) 0.19-0.85, P-trend 0.004]. Even though a comparable association between 25-OHD and ovarian cancer did not reach statistical significance (OR 0.57, 95% CI 0.26-1.24, P-trend 0.07), having sufficient (> 75 nmol/L) serum 25-OHD levels compared to insufficient serum 25-OHD was associated with a significantly decreased risk of ovarian cancer (OR 0.32; 95% CI 0.12-0.91, p-value 0.03). No synergistic protective interaction between high levels of calcium and 25-OHD against ovarian cancer was observed, the joint effect being just multiplicative.

CONCLUSION

Calcium and vitamin D act independently to reduce the risk of ovarian cancer. The decreased risk of ovarian cancer associated with pre-diagnostic serum calcium and vitamin D needs to be evaluated further for possible new insights into ovarian cancer prevention.

Meat, fish, and ovarian cancer risk: Results from 2 Australian case-control studies, a systematic review, and meta-analysis

BACKGROUND

Variation in meat and fish intakes has been associated with a risk of some cancers, but evidence for ovarian cancer is limited and inconsistent.

OBJECTIVE

We examined the association between intakes of total meat, red meat, processed meat, poultry, and fish and ovarian cancer risk.

DESIGN

Data came from 2 Australian population-based case-control studies conducted 10 y apart. Analyses included a total of 2049 cases and 2191 control subjects. We obtained dietary information via a food-frequency questionnaire. We estimated multivariable-adjusted odds ratios (ORs) for each study by using logistic regression and combined results of the 2 studies by using random-effects models. We also assembled the published evidence in a systematic review and meta-analysis.

RESULTS

Although there was no association between total or red meat intake and ovarian cancer risk, women with the highest intake of processed meat had a significantly increased risk of ovarian cancer in the 2 case-control studies (combined OR: 1.18; 95% CI: 1.15, 1.21) and the meta-analysis [7 studies; pooled relative risk (RR): 1.20; 95% CI: 1.07, 1.34]. In contrast, a frequent intake of poultry was associated with borderline significant reductions in risk in the 2 case-control studies (combined OR: 0.83; 95% CI: 0.67, 1.03) and the meta-analysis including 7 additional studies (pooled RR: 0.90; 95% CI: 0.79, 1.01). High fish intake was associated with a significantly reduced risk in the 2 case-control studies (combined OR: 0.76; 95% CI: 0.62, 0.94) and a smaller borderline significant reduction in the meta-analysis (6 additional studies; pooled RR: 0.84; 95% CI: 0.68, 1.03).

CONCLUSION

Our results suggest that low consumption of processed meat and higher consumption of poultry and fish may reduce the risk of ovarian cancer.

Circulating vitamin d and risk of epithelial ovarian cancer

We conducted a nested case-control study within two prospective cohorts, the New York University Women's Health Study and the Northern Sweden Health and Disease Study, to examine the association between prediagnostic circulating levels of 25-hydroxy vitamin D (25(OH)D) and the risk of subsequent invasive epithelial ovarian cancer (EOC). The 25(OH)D levels were measured in serum or plasma from 170 incident cases of EOC and 373 matched controls. Overall, circulating 25(OH)D levels were not associated with the risk of EOC in combined cohort analysis: adjusted OR for the top tertile versus the reference tertile, 1.09 (95% CI, 0.59–2.01). In addition, there was no evidence of an interaction effect between VDR SNP genotype or haplotype and circulating 25(OH)D levels in relation to ovarian cancer risk, although more complex gene-environment interactions may exist.

Epidemiological and genetic factors associated with ovarian cancer

The purpose of this article was to provide a comprehensive review of the epidemiological and genetic factors associated with ovarian cancer. A more complete understanding of the determinants of ovarian cancer may lead to the development of better screening and detection methods for this disease. The first section of this article reviews current literature on screening and early detection of ovarian cancer. The second section reviews the epidemiology of ovarian cancer, specifically highlighting the risk factors associated with the development of this disease. The article concludes with a discussion of how oncology nurses can apply this information to improve patient care.

[Strengthening the reporting of observational studies in epidemiology (STROBE): explanation and elaboration]

Much medical research is observational. The reporting of observational studies is often of insufficient quality. Poor reporting hampers the assessment of the strengths and weaknesses of a study and the generalisability of its results. Taking into account empirical evidence and theoretical considerations, a group of methodologists, researchers, and editors developed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) recommendations to improve the quality of reporting of observational studies. The STROBE Statement consists of a checklist of 22 items, which relate to the title, abstract, introduction, methods, results and discussion sections of articles. Eighteen items are common to cohort studies, case-control studies and cross-sectional studies and four are specific to each of the three study designs. The STROBE Statement provides guidance to authors about how to improve the reporting of observational studies and facilitates critical appraisal and interpretation of studies by reviewers, journal editors and readers. This explanatory and elaboration document is intended to enhance the use, understanding, and dissemination of the STROBE Statement. The meaning and rationale for each checklist item are presented. For each item, one or several published examples and, where possible, references to relevant empirical studies and methodological literature are provided. Examples of useful flow diagrams are also included. The STROBE Statement, this document, and the associated Web site (http://www.strobe-statement.org/) should be helpful resources to improve reporting of observational research.

The role of antioxidants and vitamin A in ovarian cancer: results from the Women's Health Initiative

Antioxidant nutrients and carotenoids have been inconsistently associated with ovarian cancer risk. We examined the relationship between intake of dietary and supplemental antioxidant nutrients including vitamins C, E, and selenium as well as carotenoids and vitamin A and ovarian cancer in 133,614 postmenopausal women enrolled in the Women's Health Initiative (WHI) study. Dietary intake was assessed using a food frequency questionnaire, and ovarian cancer endpoints were centrally adjudicated. Cox regression models were used to estimate the risk for invasive ovarian cancer in relation to each of the antioxidant nutrients and carotenoids under consideration using models stratified for a WHI study component. A total of 451 cases of invasive ovarian cancer were diagnosed over 8.3 yr of follow-up. Dietary intake at baseline was not significantly different for cases vs. controls. Cases reported greater intake of supplemental vitamin C (358.0 mg/day vs. 291.6 mg/day, respectively; P = 0.024). Multivariate modeling (P for trend) of the risk for developing ovarian cancer did not suggest any significant relationships among dietary factors and ovarian cancer risk. The results from this prospective study of well-nourished, postmenopausal women suggest that intake of dietary antioxidants, carotenoids, and vitamin A are not associated with a reduction in ovarian cancer risk.

Dietary patterns and ovarian cancer risk

BACKGROUND

Evidence for a role of individual foods and nutrients in the causation of ovarian cancer is inconclusive. To date, few studies have considered dietary patterns in relation to ovarian cancer risk.

OBJECTIVE

We conducted a population-based case-control study in Australia to identify and analyze dietary patterns in relation to ovarian cancer risk.

DESIGN

Principal components analysis of 40 food groups was performed to identify eating patterns in 683 women with epithelial ovarian cancer and in 777 control women aged 18-79 y. Detailed information on risk factors was obtained through face-to-face interviews, whereas dietary information was obtained by administering a semiquantitative food-frequency questionnaire for subjects to complete themselves. Multivariable-adjusted odds ratios (ORs) for ovarian cancer risk were estimated with logistic regression modeling.

RESULTS

Three major eating patterns were identified: "snacks and alcohol," "fruit and vegetable," and "meat and fat." A significant inverse association between the snacks and alcohol pattern and ovarian cancer risk (highest compared with lowest group, multivariable-adjusted OR: 0.59; 95% CI: 0.43, 0.82; P for trend: 0.001) was attenuated after further adjustment for white or red wine intake. The fruit and vegetable pattern was not associated with risk. The meat and fat pattern was associated with an increased risk of ovarian cancer (highest compared with lowest group, multivariable-adjusted OR: 2.49; 95% CI: 1.75, 3.55; P for trend < 0.0001). Further adjustment for body mass index strengthened this association.

CONCLUSIONS

A diet characterized by high meat and fat intake may increase the risk of epithelial ovarian cancer. A diet high in fruit and vegetables was not associated with reduced risk.

Smoking, earlier menarche and low parity as independent risk factors for gynecologic cancers in Japanese: a case-control study

During recent decades, the incidence of gynecologic cancers, i.e., cancers of the cervix, endometrium and ovary, has increased in Japan. However, risk factors of gynecologic cancers have not been fully clarified in Japan. To investigate common and site-specific risk factors among gynecologic cancers, we conducted a hospital-based case-control study. The cases, i.e., 151 cervical, 103 endometrial and 141 ovarian cancer cases and the controls (n = 2016) were selected from female patients aged 30 and over, who were admitted to a single hospital in Miyagi Prefecture from 1997 to 2003. Information on reproductive factors, exogenous hormone use, and lifestyles including smoking was collected using a self-administered questionnaire. Smoking was significantly associated with an increased risk of cervical cancer. A dose-response relationship with the number of cigarettes per day was also observed (p for trend = 0.004). Older age at menarche was associated with a decreased risk of endometrial and ovarian cancers. For these cancers, the decreased risk was detected with increasing parity number (endometrium, p for trend = 0.0001; ovary, p = 0.0002). There was no significant association between exogenous hormone use and gynecologic cancer risk. The results indicate that smoking is a major risk factor of cervical cancer. In addition, hormonal factors, which are related to early onset of menarche and low parity, are common risk factors for endometrial and ovarian cancers. The increase in female smokers and the decrease in fertility rate may contribute to the increase in gynecologic cancer incidence in Japan.

Coffee and caffeine intake and the risk of ovarian cancer: the Iowa Women's Health Study

Laboratory data suggest that caffeine or some components of coffee may cause DNA mutations and inhibit tumor suppressor mechanisms, leading to neoplastic growth. However, coffee consumption has not been clearly implicated in the etiology of human postmenopausal ovarian cancer. This study evaluated the relationship of coffee and caffeine intake with risk of epithelial ovarian cancer in a prospective cohort study of 29,060 postmenopausal women. The participants completed a mailed questionnaire that assessed diet and health history and were followed for ovarian cancer incidence from 1986 to 2004. Age-adjusted and multivariate-adjusted hazard ratios were calculated for four exposure variables: caffeinated coffee, decaffeinated coffee, total coffee, and total caffeine to assess whether or not coffee or caffeine influences the risk of ovarian cancer. An increased risk was observed in the multivariate model for women who reported drinking five or more cups/day of caffeinated coffee compared to women who reported drinking none (HR = 1.81, 95% CI: 1.10-2.95). Decaffeinated coffee, total coffee, and caffeine were not statistically significantly associated with ovarian cancer incidence. Our results suggest that a component of coffee other than caffeine, or in combination with caffeine, may be associated with increased risk of ovarian cancer in postmenopausal women who drink five or more cups of coffee a day.

Synergistic effect of high lactase activity genotype and galactose-1-phosphate uridyl transferase (GALT) mutations on idiopathic presenile cataract formation

OBJECTIVES

To evaluate the possible synergistic role of partial galactose metabolism defects, high lactase (LPH) genotype and lactose and galactose ingestion in presenile cataract formation.

DESIGN AND METHODS

51 patients with idiopathic presenile cataracts and 172 healthy cataract-free subjects were genotyped to determine their galactose-1-phosphate uridyl transferase (GALT) and LPH status. Whole milk, skimmed milk and yoghurt consumption was recorded in 19 cataract patients and 172 controls by questionnaire.

RESULTS

GALT mutations and whole milk consumption increased the risk of cataract formation in high LPH genotype group, but not in lactose intolerant subjects. Logistic regression analysis showed the synergistic effect of GALT and LPH mutations on cataract formation.

CONCLUSIONS

High lactase activity genotypes and mutations in galactose-1-phosphate uridyl transferase have a synergistic effect on presenile cataract formation.

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.

Vitamin D receptor gene polymorphisms and epithelial ovarian cancer risk

Epidemiologic and laboratory studies support a role for the vitamin D endocrine system in ovarian carcinogenesis. The association of ovarian cancer risk with polymorphisms in the vitamin D receptor (VDR) gene, including rs10735810 (FokI), rs11568820 (Cdx-2), rs1544410 (BsmI), rs7975232 (ApaI), rs731236 (TaqI), and BsmI-ApaI-TaqI combined genotypes, was examined among 313 women with epithelial ovarian carcinoma and 574 controls. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated using unconditional logistic regression. The associations of VDR polymorphisms with risk were generally inconsistent across ethnic groups. Among Caucasian women (72 cases, 148 controls), heterozygous and homozygous ApaI A allele carriers were at increased ovarian carcinoma risk compared with homozygous carriers of the ApaI a allele (OR 2.8, 95% CI 1.2-7.0 and OR 3.4, 95% CI 1.3-9.1; P(trend) = 0.02). Caucasian heterozygous carriers of FokI f allele were also at increased risk of ovarian carcinoma compared with homozygous carriers of the common allele (OR 2.5, 95% CI 1.3-4.8; P(trend) = 0.04). Among Japanese women (94 cases, 173 controls), ovarian cancer risk was significantly decreased (OR 0.5, 95% CI 0.3-0.9) among Cdx-2 A allele heterozygotes compared with homozygote G allele carriers (P(trend) = 0.03). Compared with the bbaaTT BsmI-ApaI-TaqI genotype, bbaATT and BBAAtt genotypes were associated with increased ovarian cancer risk in Caucasian women (OR 4.2, 95% CI 1.3-13.1 and OR 5.2, 95% CI 1.6-17.5), but not in Japanese women (OR 1.1, 95% CI 0.6-1.9 and OR 2.3, 95% CI:0.4-12.3). This investigation provides some evidence that polymorphisms in the VDR gene might influence ovarian cancer susceptibility.

Meat consumption and cancer risk

The authors review the key studies on the association between meat intake and cancer risk, including a new prospective cohort study by Amanda Cross and colleagues published inPLoS Medicine.

Strengthening the Reporting of Observational Studies in Epidemiology (STROBE): explanation and elaboration

Much medical research is observational. The reporting of observational studies is often of insufficient quality. Poor reporting hampers the assessment of the strengths and weaknesses of a study and the generalisability of its results. Taking into account empirical evidence and theoretical considerations, a group of methodologists, researchers, and editors developed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) recommendations to improve the quality of reporting of observational studies. The STROBE Statement consists of a checklist of 22 items, which relate to the title, abstract, introduction, methods, results and discussion sections of articles. Eighteen items are common to cohort studies, case-control studies and cross-sectional studies and four are specific to each of the three study designs. The STROBE Statement provides guidance to authors about how to improve the reporting of observational studies and facilitates critical appraisal and interpretation of studies by reviewers, journal editors and readers. This explanatory and elaboration document is intended to enhance the use, understanding, and dissemination of the STROBE Statement. The meaning and rationale for each checklist item are presented. For each item, one or several published examples and, where possible, references to relevant empirical studies and methodological literature are provided. Examples of useful flow diagrams are also included. The STROBE Statement, this document, and the associated Web site (http://www.strobe-statement.org/) should be helpful resources to improve reporting of observational research.

Glycaemic index, glycaemic load and ovarian cancer risk: a prospective cohort study

Background

There is some evidence that plasma insulin levels might influence ovarian cancer risk. Glyacemic index (GI) and glycaemic load (GL) are measures that allow the carbohydrate content of individual foods to be classified according to their postprandial glycaemic effects and hence their effects on circulating insulin levels. Therefore, we examined ovarian cancer risk in association with GI and GL, and intake of dietary carbohydrate and sugar.

Methods

The study was conducted in a prospective cohort of 49 613 Canadian women enrolled in the National Breast Screening Study (NBSS) who completed a self-administered food-frequency questionnaire (FFQ) between 1980 and 1985. Linkages to national mortality and cancer databases yielded data on deaths and cancer incidence, with follow-up ending between 1998 and 2000. Data from the FFQ were used to estimate overall GI and GL, and Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between energy-adjusted quartile levels of GL, overall GI, total carbohydrates, total sugar and ovarian cancer risk.

Results

During a mean 16.4 years of follow-up, we observed 264 incident ovarian cancer cases. GI and total carbohydrate and sugar intakes were not associated with ovarian cancer risk in the total cohort. GL was positively associated with a 72% increase in risk of ovarian cancer (HR = 1.72, 95% CI = 1.13–2.62, Ptrend = 0.01) and the magnitude of the association was slightly greater among postmenopausal (HR = 1.89, 95% CI = 0.98–3.65, Ptrend = 0.03) than among premenopausal women (HR = 1.64, 95% CI = 0.95–2.88, Ptrend = 0.07).

Conclusions

Our data suggest that consumption of diets with high GL values may be associated with increased risk of ovarian cancer.

Diet and risk of ovarian cancer in the California Teachers Study cohort

Dietary phytochemical compounds, including isoflavones and isothiocyanates, may inhibit cancer development but have not yet been examined in prospective epidemiologic studies of ovarian cancer. The authors have investigated the association between consumption of these and other nutrients and ovarian cancer risk in a prospective cohort study. Among 97,275 eligible women in the California Teachers Study cohort who completed the baseline dietary assessment in 1995-1996, 280 women developed invasive or borderline ovarian cancer by December 31, 2003. Multivariable Cox proportional hazards regression, with age as the timescale, was used to estimate relative risks and 95% confidence intervals; all statistical tests were two sided. Intake of isoflavones was associated with lower risk of ovarian cancer. Compared with the risk for women who consumed less than 1 mg of total isoflavones per day, the relative risk of ovarian cancer associated with consumption of more than 3 mg/day was 0.56 (95% confidence interval: 0.33, 0.96). Intake of isothiocyanates or foods high in isothiocyanates was not associated with ovarian cancer risk, nor was intake of macronutrients, antioxidant vitamins, or other micronutrients. Although dietary consumption of isoflavones may be associated with decreased ovarian cancer risk, most dietary factors are unlikely to play a major role in ovarian cancer development.

Dietary fiber intake and ovarian cancer risk: a prospective cohort study

There is some evidence from case-control studies that dietary fiber intake might be inversely associated with ovarian cancer risk, but there are limited prospective data. Therefore, we examined ovarian cancer risk in association with intake of dietary fiber in a prospective cohort of 49,613 Canadian women enrolled in the National Breast Screening Study (NBSS), who completed a self-administered food frequency questionnaire between 1980 and 1985. Linkages to national mortality and cancer databases yielded data on deaths and cancer incidence, with follow-up ending between 1998 and 2000. Data from the food frequency questionnaire were used to estimate intake of total dietary fiber, of fiber fractions, and of fiber from various sources. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the association between energy-adjusted quartile levels of fiber intake and ovarian cancer risk. During a mean 16.4 years of follow-up, we observed 264 incident ovarian cancer cases. Total dietary fiber and fiber fractions were not associated with ovarian cancer risk in this study population.

Dietary folate consumption and risk of ovarian cancer: a prospective cohort study

Deficient dietary folate intake may be associated with increased cancer risk in humans owing to DNA damage resulting from impaired nucleotide excision repair. It is conceivable that an association with folate may be modified by alcohol and/or methionine intake given that alcohol consumption and low methionine intakes both increase dietary folate requirements. In the cohort study reported here, we examined the association between dietary folate intake and ovarian cancer risk, overall and within strata defined by alcohol and methionine intakes. The investigation was conducted in 49 613 Canadian women who were participants in the National Breast Screening Study and who completed self-administered lifestyle and food frequency questionnaires between 1980 and 1985. Linkages to cancer and national mortality databases yielded data on cancer incidence and deaths among cohort members, with follow-up ending between 1998 and 2000. During a mean 16.4 years of follow-up, we observed 264 incident ovarian cancer cases among 48 766 women for whom data were available. Dietary folate intake was associated with a 25% decrease in risk of ovarian cancer for the highest versus the lowest quartile level of intake (hazard ratio=0.75, 95% confidence interval=0.42-1.34, Ptrend=0.25). On stratification by alcohol intake, dietary folate was not associated with ovarian cancer risk among women consuming <4 g/day of alcohol, but there was some suggestion of reduced risk at relatively high levels of folate intake among women consuming > or =4 g/day of alcohol/day (Ptrend=0.09; Pinteraction=0.22). The association between folate and ovarian cancer risk did not vary by strata of methionine intake (Pinteraction=0.98). Our findings, while not statistically significant, suggest that relatively high dietary folate intake may be associated with a reduction in ovarian cancer risk among women with relatively high alcohol consumption and among those with relatively high methionine intake.

Fruit and vegetables in cancer prevention

Our aim was to review the epidemiological literature on possible cancer-preventive effects of the consumption of fruits and vegetables in humans, to quantify the effect of high versus low consumption of fruits and vegetables, and to give an overall assessment of the existing evidence. We based our work on an expert meeting conducted by the International Agency for Research on Cancer in 2003. A qualitative reading and evaluation of relevant articles on the cancer-preventive effect of the consumption of fruits and vegetables was made followed by the calculation of the mean relative risk and range for cohort and case-control studies separately. The possible population-preventable fraction for modifying diet in relation to fruit and vegetable consumption was calculated as well as an overall statement about the degree of evidence for the cancer-preventive effect of fruit and vegetable consumption for each cancer site. There is limited evidence for a cancer-preventive effect of the consumption of fruits and vegetables for cancer of the mouth and pharynx, esophagus, stomach, colon-rectum, larynx, lung, ovary (vegetables only), bladder (fruit only), and kidney. There is inadequate evidence for a cancer-preventive effect of the consumption of fruits and vegetables for all other sites. Applying this range of risk difference to the range of prevalence of low intake, the preventable fraction for low fruit and vegetable intake would fall into the range of 5-12%. It is important to recognize that this is only a crude range of estimates and that the proportion of cancers that might be preventable by increasing fruit and vegetable intake may vary beyond this range for specific cancer sites and across different regions of the world.

Alcohol consumption and ovarian cancer risk in a population-based case-control study

Alcohol consumption has been investigated as a possible risk factor for ovarian cancer in several epidemiological studies, with inconsistent findings. Recent studies have suggested that the association between alcohol consumption and ovarian cancer may vary according to histologic subtype of ovarian cancer and type of alcohol consumed (e.g., wine, beer, or liquor). We examined these associations in a population-based case-control study comprised of 762 incident cases of epithelial ovarian cancer and 6,271 population controls from Massachusetts and Wisconsin aged 40-79 years. Women reported their usual alcohol consumption as young adults (20-30 years of age) and in the recent past. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. There was no significant association of ovarian cancer with increasing alcohol consumption either during ages 20-30 years (p trend 0.42) or in the recent past (p trend 0.83). Regular drinking of beer (1 drink/day or more) during ages 20-30 (OR 1.55, 95% CI 1.07-2.26), though not liquor (OR 1.35, 95% CI 0.86-2.11) or wine (OR 0.99, 95% CI 0.49-2.00), was associated with a statistically significant increase in risk of invasive tumors, whereas no significant relationships were observed for recent drinking, regardless of alcohol type. The elevated risk for early adult regular drinking was confined to serous invasive tumors (OR 1.52, 95% CI 1.01-2.30), though results for other subtypes were based on sparse data and results were imprecise. In this study, neither total alcohol consumption as a young adult nor recently was associated with an increase in the risk of ovarian cancer.

Milk, dairy products and cancer risk (Italy)

BACKGROUND

Inconclusive information is available on the potential role of milk and dairy products on the risk of cancer at several sites.

METHODS

We analyzed data from a large and integrated network of hospital-based case-control studies in Italy on cancers of the oral cavity and pharynx (598 cases, 1491 controls), oesophagus (304 cases, 743 controls), colorectum (1953 cases, 4154 controls), larynx (460 cases, 1088 controls), breast (2569 cases, 2588 controls), ovary (1031 cases, 2411 controls) and prostate (1294 cases, 1451 controls).

RESULTS

Multivariate odds ratio (OR) for the highest consumption level of any type of milk was 0.94 (95% confidence interval, CI: 0.61-1.33) for cancers of the oral cavity and pharynx, 1.20 (95% CI: 0.76-1.90) for oesophageal, 0.77 (95% CI: 0.62-0.96) for colon, 0.80 (95% CI: 0.60-1.05) for rectal, 0.83 (95% CI: 0.56-1.21) for laryngeal, 0.91 (95% CI: 0.76-1.10) for breast, 0.89 (95% CI: 0.68-1.15) for ovarian and 1.08 (95% CI: 0.84-1.37) for prostate cancer. A significant trend in risk was found for colon cancer only. Inverse associations were observed between consumption of skim milk and cancers of colon (OR=0.84; 95% CI: 0.73-0.97), rectum (OR=0.76; 95% CI: 0.64-0.91), breast (OR=0.87; 95% CI: 0.77-0.98) and ovary (OR=0.77; 95% CI: 0.66-0.91). Conversely, whole milk consumption was directly associated with cancer of the rectum (OR=1.22; 95% CI: 1.03-1.44) and ovary (OR=1.25; 95% CI: 1.07-1.46). High consumption of cheese was inversely related to colon cancer risk (OR=0.80; 95% CI: 0.67-0.95).

CONCLUSIONS

There was a modest direct association between milk and dairy products and prostate cancer, and a moderate inverse one for colorectal cancer. However, our findings indicate that milk and dairy products are not strong risk indicators for any of the cancers considered.

Relationship Between Calcium, Lactose, Vitamin D, and Dairy Products and Ovarian Cancer

Few prospective studies of the relationship between intake of dairy foods, calcium, vitamin D, and lactose and ovarian cancer have been conducted, and results have been largely inconsistent. Two recent studies found significant increased risk with frequent dairy consumption and perhaps with high intakes of calcium or lactose. The authors investigated the association between these foods and nutrients and ovarian cancer risk among 31,925 subjects in the Breast Cancer Detection Demonstration Project follow-up cohort. Multivariable (MV) relative risks (RRs) adjusted for age, parity, and other factors were estimated using Cox proportional hazards models. Over an average follow-up of 8.3 yr, 146 incident ovarian cancer cases were confirmed. Higher intakes of total dairy food (comparing four or more servings per day vs. less than one serving per day) were associated with a statistically significant decreased risk of ovarian cancer, although the trend was not significant (MV RR = 0.42; 95% confidence interval (CI) = 0.20-0.89; P for trend = 0.07). Comparing extreme quartiles, we observed a statistically nonsignificant inverse association between high dietary calcium intake and ovarian cancer (RR = 0.67; 95% CI = 0.43, 1.04; P for trend = 0.08). No statistically significant relations were found for consumption of specific dairy foods, lactose, or vitamin D and ovarian cancer risk. The possibility of a decreased risk of ovarian cancer for dietary calcium merits further evaluation.

Dietary intake changes and their association with ovarian cancer risk

There are reasons to suspect that dietary changes through adult life may modify risk for some cancers. We examined the association of recent and past dietary habits and changes in dietary intake over time with ovarian cancer risk. Long-term nutritional assessment was performed retrospectively in 631 incident cases of invasive epithelial ovarian cancer and in 1174 matched controls (matched by age +/- 2 y, country of origin, and period of immigration) as part of a nationwide case-control study of ovarian cancer conducted between the years of 1994 and 1996 in Israel. Using a 2-step quantified Food Frequency Questionnaire, participants were first asked about their consumption of food items 1 y prior to the interview, and then whether their consumption had changed over time. The time of the change and consumption level before the change were recorded, allowing reconstruction of daily intakes for several time points. The reported mean percentage of animal fat intake decreased by 1.3% in cases but by 1.9% in controls (P for difference = 0.003). Conditional multivariate logistic regression was used to estimate odds ratios adjusted for total energy, parity, and oral contraceptive use. Substituting nonanimal fat in preference to animal fat over a relatively short term (between 2 and 7 y prior to interview) decreased the risk of ovarian cancer [OR = 0.65/100 kcal (418.4 kJ), 95% CI = 0.50 - 0.85]. Our results suggest that substitution of nonanimal for animal fat during adult life might reduce the risk of ovarian cancer, but this requires confirmation in prospective studies.

Association of Reproductive Factors, Oral Contraceptive Use and Selected Lifestyle Factors with the Risk of Ovarian Borderline Tumors: A Danish Case-control Study

OBJECTIVE

The aim was to examine risk factors for ovarian borderline tumors overall, and according to histological subtype (serous vs. mucinous), in a large Danish population-based case-control study.

METHODS

Ovarian borderline cases and controls were recruited from 1995 to 1999, and personal interviews were conducted. In all, 202 cases and 1,564 randomly selected controls were included. The analysis was performed using multiple logistic regression models.

RESULTS

The risk of ovarian borderline disease decreased with increasing parity (OR=0.79 per birth, 95% CI: 0.63-0.98) and older age at first birth (OR=0.67 per 5 years, 95% CI: 0.53-0.84). Both a history of breastfeeding and use of oral contraceptives reduced the risk of borderline tumor, the effect being most pronounced for serous tumors. Increasing body mass index (BMI) was associated with elevated risk of serous borderline tumor (OR=1.05 per BMI unit; 95% CI: 1.00-1.10), whereas current smoking was a strong risk factor only for mucinous tumors (OR=2.10; 95% CI: 1.22-3.60). Finally, increasing consumption of milk (all types) was found to increase the risk of borderline disease (OR=1.04 per glass milk per week; 95% CI: 1.02-1.06), and increasing intake of total lactose also increased the risk significantly (OR=1.16 per 50 gram lactose per week; 95% CI: 1.06-1.26).

CONCLUSION

The risk profile of ovarian borderline tumors is similar to that of ovarian carcinomas, and we observed significant etiological differences between serous and mucinous borderline tumors.

Intake of the major carotenoids and the risk of epithelial ovarian cancer in a pooled analysis of 10 cohort studies

Carotenoids, found in fruits and vegetables, have the potential to protect against cancer because of their properties, including their functions as precursors to vitamin A and as antioxidants. We examined the associations between intakes of alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein/zeaxanthin and lycopene and the risk of invasive epithelial ovarian cancer. The primary data from 10 prospective cohort studies in North America and Europe were analyzed and then pooled. Carotenoid intakes were estimated from a validated food frequency questionnaire administered at baseline in each study. Study-specific relative risks (RR) were estimated using the Cox proportional hazards model and then combined using a random-effects model. Among 521,911 women, 2,012 cases of ovarian cancer occurred during a follow-up of 7-22 years across studies. The major carotenoids were not significantly associated with the risk of ovarian cancer. The pooled multivariate RRs (95% confidence intervals) were 1.00 (0.95-1.05) for a 600 microg/day increase in alpha-carotene intake, 0.96 (0.93-1.03) for a 2,500 microg/day increase in beta-carotene intake, 0.99 (0.97-1.02) for a 100 microg/day increase in beta-cryptoxanthin intake, 0.98 (0.94-1.03) for a 2,500 microg/day increase in lutein/zeaxanthin intake and 1.01 (0.97-1.05) for a 4,000 microg/day increase in lycopene intake. These associations did not appreciably differ by study (p-values, tests for between-studies heterogeneity >0.17). Also, the observed associations did not vary substantially by subgroups of the population or by histological type of ovarian cancer. These results suggest that consumption of the major carotenoids during adulthood does not play a major role in the incidence of ovarian cancer.

Role of glutathione-S-transferase and codon 72 of P53 genotypes in epithelial ovarian cancer patients

PURPOSE

A series of polymorphisms in germ-line DNA have been investigated in an effort to delineate polygenic models of cancer susceptibility and prognosis. As low-penetrance susceptibility genes may combine additively or multiplicatively and contribute to cancer incidence and to the response to chemotherapy, we studied GSTT1, GSTM1, GSTO2, GSTP1 and codon 72 of p53 genotype profiles in ovarian cancer patients.

METHODS

We compared 69 ovarian cancer patients with 222 control healthy women paired for ethnic and life-style characteristics. Outcome was evaluated in 29 stage III and IV patients submitted to a platinum-based chemotherapy followed-up for 6-29 months (17 +/- 9 months).

RESULTS

GSTT1, GSTM1, GSTO2 and GSTP1 genes presented a similar genotype distribution, but codon 72 of p53 gene wild-type variant was less frequent in ovarian cancer patients than in controls (chi(2); P = 0.0004).

CONCLUSIONS

We were unable to demonstrate any association between the GST genotypes studied and the risk of ovarian cancer but the inheritance of a heterozygous Arg/Pro genotype of p53 increased the risk of ovarian cancer more than 2.5 times (OR = 2.571; 95% CI = 1.453-4.550). There was no association of the studied genes to any clinical or pathological feature of the patients or to their response to chemotherapy.

Dietary risk factors for ovarian cancer: the Adventist Health Study (United States)

Few prospective studies have reported dietary risk factors for ovarian cancer. A total of 71 histologically confirmed epithelial ovarian cancers occurred among 13,281 non-Hispanic white California Seventh-day Adventist women during follow-up. Participants were part of the Adventist Health Study (AHS) and had no history of cancer or hysterectomy at baseline in 1976 when they completed a detailed lifestyle questionnaire including a dietary assessment. The association of dietary variables with either all ovarian cancer cases or postmenopausal cases was tested using proportional hazards regression with adjustment for age and other covariates. The strongest hazardous risk factor associations among the food variables were found for meat intake with a risk ratio (RR) of 2.42 for intake > or = 1 time/week versus no meat (p for trend = 0.006), and cheese intake with a RR of 2.02 for intake of > 2 time/week versus < 1 per week (p for trend = 0.10), both of these being in postmenopausal cases. We found significantly reduced risk of all ovarian cancer with higher tomato consumption (RR = 0.32) comparing intakes > or = five times/week versus never to < 1 time/week (p for trend = 0.002), and also with higher fruit consumption (p < 0.01). A weak protective association was found with low fat, but not whole milk. Little confounding was observed between these foods.

A Pooled Analysis of 12 Cohort Studies of Dietary Fat, Cholesterol and Egg Intake and Ovarian Cancer

Fat and cholesterol are theorized to promote ovarian carcinogenesis by increasing circulating estrogen levels. Although case-control studies have reported positive associations between total and saturated fat intake and ovarian cancer risk, two cohort studies have observed null associations. Dietary cholesterol and eggs have been positively associated with ovarian cancer risk. A pooled analysis was conducted on 12 cohort studies. Among 523,217 women, 2,132 incident epithelial ovarian cancer cases were identified. Study-specific relative risks (RR) and 95% confidence intervals (CI) were calculated by Cox proportional hazards models, and then pooled using a random effects model. Total fat intake was not associated with ovarian cancer risk (pooled multivariate RR = 1.08, 95% CI 0.86-1.34 comparing > or =45 to 30-<35% of calories). No association was observed for monounsaturated, polyunsaturated, trans-unsaturated, animal and vegetable fat, cholesterol and egg intakes with ovarian cancer risk. A weakly positive, but non-linear association, was observed for saturated fat intake (pooled multivariate RR = 1.29, 95% CI: 1.01-1.66 comparing highest versus lowest decile). Results for histologic subtypes were similar. Overall, fat, cholesterol and egg intakes were not associated with ovarian cancer risk. The positive association for saturated fat intake at very high intakes merits further investigation.

Dairy consumption and ovarian cancer risk in the Netherlands Cohort Study on Diet and Cancer

Ovary cancer risk in relation to consumption of dairy products was investigated using a self-administered questionnaire on dietary habits and other risk factors for cancer, which was completed in 1986 by 62 573 postmenopausal women participating in the Netherlands Cohort Study. Follow-up for cancer was implemented by annual record linkage with the Netherlands Cancer Registry and a nationwide pathology registry. After 11.3 years of follow-up, data of 252 incident epithelial ovarian cancer cases and 2216 subcohort members were available for analysis. No association was seen between consumption of milk, yoghurt, cheese or fermented dairy products and ovarian cancer risk. The multivariable adjusted relative risk of epithelial ovarian cancer for women in the highest compared to the lowest quintile of intake of lactose or dairy fat was 0.93 (95% confidence interval (CI)=0.60–1.45; P_trend=0.32) and 1.53 (95% CI=1.00–2.36; P_trend=0.11), respectively. Lactose or dairy fat intakes were not associated with serous ovarian cancer risk. Our results do not support an association between consumption of dairy products or lactose intake and ovarian cancer.

Dairy products and ovarian cancer: a pooled analysis of 12 cohort studies

BACKGROUND

Dairy foods and their constituents (lactose and calcium) have been hypothesized to promote ovarian carcinogenesis. Although case-control studies have reported conflicting results for dairy foods and lactose, several cohort studies have shown positive associations between skim milk, lactose, and ovarian cancer.

METHODS

A pooled analysis of the primary data from 12 prospective cohort studies was conducted. The study population consisted of 553,217 women among whom 2,132 epithelial ovarian cases were identified. Study-specific relative risks and 95% confidence intervals were calculated by Cox proportional hazards models and then pooled by a random-effects model.

RESULTS

No statistically significant associations were observed between intakes of milk, cheese, yogurt, ice cream, and dietary and total calcium intake and risk of ovarian cancer. Higher lactose intakes comparing > or = 30 versus <10 g/d were associated with a statistically significant higher risk of ovarian cancer, although the trend was not statistically significant (pooled multivariate relative risk, 1.19; 95% confidence interval, 1.01-1.40; P(trend) = 0.19). Associations for endometrioid, mucinous, and serous ovarian cancer were similar to the overall findings.

DISCUSSION

Overall, no associations were observed for intakes of specific dairy foods or calcium and ovarian cancer risk. A modest elevation in the risk of ovarian cancer was seen for lactose intake at the level that was equivalent to three or more servings of milk per day. Because a new dietary guideline recommends two to three servings of dairy products per day, the relation between dairy product consumption and ovarian cancer risk at these consumption levels deserves further examination.

Milk, milk products and lactose intake and ovarian cancer risk: a meta-analysis of epidemiological studies

It has been proposed, on the basis of animal models and ecological studies, that consumption or metabolism of dairy sugar may increase the risk of ovarian cancer. Case-control and cohort studies of the association between lactose and dairy food consumption and ovarian cancer risk, however, have yielded varied findings. We summarized the available literature on this topic using a meta-analytic approach. Random-effects models were used to estimate the summary relative risks (RR(summary)). A linear regression analysis of the natural logarithm of the RR was carried out to assess a possible dose-response relationship between lactose intake and ovarian cancer risk. Eighteen case-control and 3 prospective cohort studies were eligible for inclusion in the meta-analysis. The findings of case-control studies were heterogeneous, and, except for whole milk (RR(summary) for highest vs. lowest category = 1.27, 95% confidence interval [CI] = 0.97-1.68), do not provide evidence of positive associations between dairy food and lactose intakes with risk of ovarian cancer. In contrast, the 3 cohort studies are consistent and show significant positive associations between intakes of total dairy foods, low-fat milk, and lactose and risk of ovarian cancer. The RR(summary) for a daily increase of 10 g in lactose intake (the approximate amount in 1 glass of milk) was 1.13 (95% CI = 1.05-1.22) for cohort studies. In conclusion, prospective cohort studies, but not case-control studies, support the hypothesis that high intakes of dairy foods and lactose may increase the risk of ovarian cancer.

Prospective studies of dairy product and calcium intakes and prostate cancer risk: a meta-analysis

BACKGROUND

The Dietary Guidelines for Americans 2005 recommends that Americans increase their intake of dairy products. However, some studies have reported that increasing dairy product intake is associated with an increased risk of prostate cancer. We conducted a meta-analysis to examine associations between intakes of calcium and dairy products and the risk of prostate cancer.

METHODS

We searched Medline for prospective studies published in English-language journals from 1966 through May 2005. We identified 12 publications that used total, advanced, or fatal prostate cancer as end points and reported associations as relative risks (RRs) with 95% confidence intervals (CIs) by category of dairy product or calcium intake. Data were extracted using standardized data forms. Random-effects models were used to pool study results and to assess dose-response relationships between dairy product or calcium intakes and the risk of prostate cancer. We conducted sensitivity analyses by changing criteria for inclusion of studies or by using fixed-effects models. All statistical tests were two-sided.

RESULTS

Men with the highest intake of dairy products (RR =1.11 [95% CI = 1.00 to 1.22], P = .047) and calcium (RR = 1.39 [95% CI = 1.09 to 1.77], P = .018) were more likely to develop prostate cancer than men with the lowest intake. Dose-response analyses suggested that dairy product and calcium intakes were each positively associated with the risk of prostate cancer (Ptrend = .029 and .014, respectively). Sensitivity analyses generally supported these associations, although the statistical significance was attenuated. The pooled relative risks of advanced prostate cancer were 1.33 (95% CI = 1.00 to 1.78; P = .055) for the highest versus lowest intake categories of dairy products and 1.46 (95% CI = 0.65 to 3.25; P > .2) for the highest versus lowest intake categories of calcium.

CONCLUSIONS

High intake of dairy products and calcium may be associated with an increased risk of prostate cancer, although the increase appears to be small.

Fruit and Vegetable Consumption and Risk of Epithelial Ovarian Cancer: The European Prospective Investigation into Cancer and Nutrition

OBJECTIVE

The association between consumption of fruit and vegetables and risk of ovarian cancer is still unclear from a prospective point of view.

METHODS

Female participants (n = 325,640) of the European Prospective Investigation into Cancer and Nutrition study, free of any cancer at baseline, were followed on average for 6.3 years to develop ovarian cancer. During 2,049,346 person-years, 581 verified cases of primary, invasive epithelial ovarian cancer were accrued. Consumption of fruits and vegetables as well as subgroups of vegetables, estimated from validated dietary questionnaires and calibrated thereafter, was related to ovarian cancer incidence in multivariable hazard regression models. Histologic subtype specific analyses were done.

RESULTS

Total intake of fruit and vegetables, separately or combined, as well as subgroups of vegetables (fruiting, root, leafy vegetables, cabbages) was unrelated to risk of ovarian cancer. A high intake of garlic/onion vegetables was associated with a borderline significant reduced risk of this cancer. The examination by histologic subtype indicated some differential effects of fruit and vegetable intake on ovarian cancer risk.

CONCLUSION

Overall, a high intake of fruits and vegetables did not seem to protect from ovarian cancer. Garlic/onion vegetables may exert a beneficial effect. The study of the histologic subtype of the tumor warrants further investigation.

Lactase persistence and ovarian carcinoma risk in Finland, Poland and Sweden

Ovarian carcinoma is the fourth most common cause of cancer death in women. The cause and pathogenesis of this disease has remained obscure. Galactose, the hydrolyzing product of the milk sugar lactose, has been hypothesized to be toxic to ovarian epithelial cells and consumption of dairy products and lactase persistence has been suggested to be a risk factor for ovarian carcinoma. In adults, downregulation of lactase depends on a variant C/T-13910 at the 5' end of the lactase gene. To explore whether lactase persistence is related to the risk of ovarian carcinoma we determined the C/T-13910 genotype in a cohort of 782 women with ovarian carcinoma. The C/T-13910 genotype was defined by solid phase minisequencing from 327 Finnish, 303 Polish, 152 Swedish patients and 938 Finnish, 296 Polish and 97 Swedish healthy individuals served as controls. Lactase persistence did not associate significantly with increased risk for ovarian carcinoma in the Finnish (odds ratio [OR]=0.77, 95% confidence interval [CI]=0.57-1.05, p=0.097), in the Polish (OR=0.95, 95% CI=0.68-1.33, p=0.75), or in the Swedish populations (OR=1.63, 95% CI=0.65-4.08, p=0.29). Our results do not support the hypothesis that lactase persistence increases the ovarian carcinoma risk. On the contrary, lactase persistence may decrease the ovarian carcinoma risk at least in the Finnish population.

Consumption of vegetables and fruits and risk of ovarian carcinoma

BACKGROUND

To the authors' knowledge, only a few prospective studies to date have investigated the correlation between vegetable and fruit consumption and the risk of ovarian carcinoma and their results have been inconclusive.

METHODS

Vegetable and fruit intake was assessed in relation to ovarian carcinoma, among 62,573 postmenopausal women participating in The Netherlands Cohort Study on Diet and Cancer. Women reported on dietary habits and on other risk factors for cancer in a self-administered questionnaire in 1986. Follow-up of cancer was implemented by annual record linkage with The Netherlands Cancer Registry and a pathology register. After 11.3 years of follow-up, data regarding 252 incident invasive epithelial ovarian carcinoma cases and of 2216 subcohort members were available for case-cohort analyses.

RESULTS

Multivariable-adjusted rate ratios (RR) of ovarian carcinoma for women in the highest compared with the lowest quintile of intake (RR(Q5 vs. Q1)) were 0.98 (95% confidence interval [95% CI], 0.61-1.58) for total vegetables and 1.11 (95% CI, 0.70-1.78) for total fruit. The RR(Q5 vs. Q1) values of ovarian carcinoma with intake of cooked vegetables, raw vegetables, brassicas, legumes, cooked leafy vegetables, and raw leafy vegetables were 1.35 (95% CI, 0.83-2.21), 0.75 (95% CI, 0.48-1.18), 1.42 (95% CI, 0.88-2.29), 0.93 (95% CI, 0.60-1.44), 1.05 (95% CI, 0.66-1.67), and 1.23 (95% CI, 0.75-2.02), respectively. With the exception of raw endive (multivariable-adjusted RR, 0.24; 95% CI, 0.07-0.78), none of the individual vegetable or fruit items showed a statistically significant association with ovarian carcinoma.

CONCLUSIONS

The results of the current study did not support a significant association between vegetable or fruit consumption and ovarian carcinoma risk in a cohort of postmenopausal women.