Dairy foods, calcium intakes, and risk of incident prostate cancer in Adventist Health Study-2.

BACKGROUND: Prostate cancer is the most common noncutaneous cancer in American males. Causal links between dairy, or dietary calcium, and this cancer are considered suggestive but limited. OBJECTIVES: To evaluate these associations in a large North American cohort, including many with no (or very low) dairy intake and much calcium from nondairy sources. METHODS: A prospective cohort study of 28,737 Seventh-day Adventist men in the United States and Canada, of whom 6389 were of black ethnicity. Diet was measured by FFQ, and 275 male participants also provided repeated 24-h dietary recalls as a calibration substudy. Incident cancers were mainly found by matching with cancer registries. Analyses used multivariable proportional hazards regressions and regression calibration for some analyses. RESULTS: In total, 1254 (190 advanced) incident prostate cancer cases were found during an average 7.8 y of follow-up. Men at the 90th percentile of dairy intake (430 g/d) compared with the 10th percentile (20.2 g/d) had higher prostate cancer risk (HR: 1.27; 95% CI: 1.12, 1.43). Similar findings, comparing the same g/d intakes, were demonstrated for advanced prostate cancers (HR: 1.38; 95% CI: 1.02, 1.88), for nonadvanced cases (HR: 1.27; 95% CI: 1.11, 1.45), in black participants (HR: 1.24; 95% CI: 0.98, 1.58), and when excluding vegan participants (HR: 1.22; 95% CI: 1.03, 1.43). Calibrated dairy (g/d) regressions (all participants and all prostate cancers), adjusting for dietary measurement error, found a HR of 1.75 (95% CI: 1.32, 2.32). Comparing 90th percentile intake to zero intakes (uncalibrated), the HR was 1.62 (95% CI: 1.26, 2.05). There was no evidence of an effect of higher (905 mg/d) compared with lower (349 mg/d) intakes of nondairy calcium (HR: 1.16; 95% CI: 0.94, 1.44). CONCLUSIONS: Men with higher intake of dairy foods, but not nondairy calcium, had a higher risk of prostate cancer compared with men having lower intakes. Associations were nonlinear, suggesting greatest increases in risk at relatively low doses.

Lower Utilization of Colorectal Cancer Screening Among Vegetarians, Adventist Health Study-2.

This study aims to examine lifestyle predictors of the utilization of colorectal cancer screening. Using modified Poisson regression, we studied self-reported colorectal cancer screening utilization (colonoscopy or fecal occult blood test) with various dietary and lifestyle characteristics among 33,922 subjects aged 51 + years in the Adventist Health Study-2, a large population-based prospective cohort study. According to the multivariable-adjusted models, vegetarians were less likely to report screening: vegans, prevalence ratio (PR) = 0.80 (95% confidence interval 0.77-0.83); lacto-ovo-vegetarians (0.95 [0.93-0.97]); and semi-vegetarians (0.97 [0.94-0.99]) compared to non-vegetarians. Blacks were more likely than non-Blacks to be screened (1.04 [1.02-1.06]) and males were less likely (0.93 [0.92-0.95]) to utilize the screening tests. Older subjects were more likely to be screened, and unmarried and divorced/widowed subjects were less likely to screen. Education, personal income, and BMI were positively associated with screening, with p-value for trend < 0.001 for all three variables. A family history of colorectal cancer was associated with higher screening prevalence (1.15 [1.12-1.17]). Our stratified analyses on race and gender with dietary patterns showed non-Hispanic White vegans (PR = 0.77 [0.74-0.81]) and male vegans (PR = 0.76 [0.72-0.81]) were least likely compliant with colorectal cancer screening (p = 0.009 and p = 0.04, respectively). Vegans may believe that their personal risk for colorectal cancer is low due to their healthy lifestyle, resulting in lack of compliance to colorectal cancer screening. It remains to be seen whether vegans in AHS-2 also experience higher incidence of colorectal cancer or are diagnosed at a later stage.

Ovarian Cancer Risk Factor Associations by Primary Anatomic Site: The Ovarian Cancer Cohort Consortium.

BACKGROUND: Epithelial ovarian, fallopian tube, and primary peritoneal cancers have shared developmental pathways. Few studies have prospectively examined heterogeneity in risk factor associations across these three anatomic sites. METHODS: We identified 3,738 ovarian, 337 peritoneal, and 176 fallopian tube incident cancer cases in 891,731 women from 15 prospective cohorts in the Ovarian Cancer Cohort Consortium. Associations between 18 putative risk factors and risk of ovarian, peritoneal, and fallopian tube cancer, overall and for serous and high-grade serous tumors, were evaluated using competing risks Cox proportional hazards regression. Heterogeneity was assessed by likelihood ratio tests. RESULTS: Most associations did not vary by tumor site (P het ≥ 0.05). Associations between first pregnancy (P het = 0.04), tubal ligation (P het = 0.01), and early-adult (age 18-21 years) body mass index (BMI; P het = 0.02) and risk differed between ovarian and peritoneal cancers. The association between early-adult BMI and risk further differed between peritoneal and fallopian tube cancer (P het = 0.03). First pregnancy and tubal ligation were inversely associated with ovarian, but not peritoneal, cancer. Higher early-adult BMI was associated with higher risk of peritoneal, but not ovarian or fallopian tube, cancer. Patterns were generally similar when restricted to serous and high-grade serous cases. CONCLUSIONS: Ovarian, fallopian tube, and primary peritoneal cancers appear to have both shared and distinct etiologic pathways, although most risk factors appear to have similar associations by anatomic site. IMPACT: Further studies on the mechanisms underlying the differences in risk profiles may provide insights regarding the developmental origins of tumors arising in the peritoneal cavity and inform prevention efforts.

Lower rates of cancer and all-cause mortality in an Adventist cohort compared with a US Census population.

BACKGROUND: Previous research suggests that Adventists, who often follow vegetarian diets, live longer and have lower risks for many cancers than others, but there are no national data and little published comparative data for black subjects. METHODS: This study compared all-cause mortality and cancer incidence between the nationally inclusive Adventist Health Study 2 (AHS-2) and nonsmokers in US Census populations: the National Longitudinal Mortality Study (NLMS) and its Surveillance, Epidemiology, and End Results substudy. Analyses used proportional hazards regression adjusting for age, sex, race, cigarette smoking history, and education. RESULTS: All-cause mortality and all-cancer incidence in the black AHS-2 population were significantly lower than those for the black NLMS populations (hazard ratio [HR] for mortality, 0.64; 95% confidence interval [CI], 0.59-0.69; HR for incidence, 0.78; 95% CI, 0.68-0.88). When races were combined, estimated all-cause mortality was also significantly lower in the AHS-2 population at the age of 65 years (HR, 0.67; 95% CI, 0.64-0.69) and at the age of 85 years (HR, 0.78; 95% CI, 0.75-0.81), as was cancer mortality; this was also true for the rate of all incident cancers combined (HR, 0.70; 95% CI, 0.67-0.74) and the rates of breast, colorectal, and lung cancers. Survival curves confirmed the mortality results and showed that among males, AHS-2 blacks survived longer than white US subjects. CONCLUSIONS: Substantially lower rates of all-cause mortality and cancer incidence among Adventists have implications for the effects of lifestyle and perhaps particularly diet on the etiology of these health problems. Trends similar to those seen in the combined population are also found in comparisons of black AHS-2 and NLMS subjects.

Vegetarian Epidemiology: Review and Discussion of Findings from Geographically Diverse Cohorts.

Epidemiologic cohort studies enrolling a large percentage of vegetarians have been highly informative regarding the nutritional adequacy and possible health effects of vegetarian diets. The 2 largest such cohorts are the European Prospective Investigation into Cancer and Nutrition-Oxford (EPIC-Oxford) and the Adventist Health Study-2 (AHS-2). These cohorts are described and their findings discussed, including a discussion of where findings appear to diverge. Although such studies from North America and the United Kingdom have been important, the large majority of the world's vegetarians live in other regions, particularly in Asia. Findings from recent cohort studies of vegetarians in East and South Asia are reviewed, particularly the Tzu Chi Health Study and Indian Migration Study. Important considerations for the study of the health of vegetarians in Asia are discussed. Vegetarian diets vary substantially, as may associated health outcomes. Cohort studies remain an important tool to better characterize the health of vegetarian populations around the globe.

Red and Processed Meat and Mortality in a Low Meat Intake Population.

Associations of low-to-moderate consumption of red and processed meat with mortality would add to the evidence of possible adverse effects of these common foods. This study aims to investigate the association of red and processed meat intake with mortality. The Adventist Health Study-2 (AHS-2) is a prospective cohort study of ~96,000 Seventh-day Adventist men and women recruited in the US and Canada between 2002 and 2007. The final analytic sample after exclusions was 72,149. Cox proportional hazards regression was used and hazard ratios (HR) and confidence intervals (CI) were obtained. Diet was assessed by a validated quantitative food frequency questionnaire (FFQ), calibrated using six 24-h dietary recalls. Mortality outcome data were obtained from the National Death Index. During a mean follow-up of 11.8 years, there were 7961 total deaths, of which 2598 were Cardiovascular diseases (CVD) deaths and 1873 were cancer deaths. Unprocessed red meat was associated with risk of all-cause mortality (HR: 1.18; 95% CI: 1.07⁻1.31) and CVD mortality (HR: 1.26; 95% CI: 1.05⁻1.50). Processed meat alone was not significantly associated with risk of mortality. The combined intake of red and processed meat was associated with all-cause mortality (HR: 1.23; 95% CI: 1.11⁻1.36) and CVD mortality (HR: 1.34; 95% CI: 1.12⁻1.60). These findings suggest moderately higher risks of all-cause and CVD mortality associated with red and processed meat in a low meat intake population.

Next steps in studying the human microbiome and health in prospective studies, Bethesda, MD, May 16-17, 2017.

The National Cancer Institute (NCI) sponsored a 2-day workshop, "Next Steps in Studying the Human Microbiome and Health in Prospective Studies," in Bethesda, Maryland, May 16-17, 2017. The workshop brought together researchers in the field to discuss the challenges of conducting microbiome studies, including study design, collection and processing of samples, bioinformatics and statistical methods, publishing results, and ensuring reproducibility of published results. The presenters emphasized the great potential of microbiome research in understanding the etiology of cancer. This report summarizes the workshop and presents practical suggestions for conducting microbiome studies, from workshop presenters, moderators, and participants.

Vegetarian dietary patterns and the risk of colorectal cancers.

IMPORTANCE: Colorectal cancers are a leading cause of cancer mortality, and their primary prevention by diet is highly desirable. The relationship of vegetarian dietary patterns to colorectal cancer risk is not well established. OBJECTIVE: To evaluate the association between vegetarian dietary patterns and incident colorectal cancers. DESIGN, SETTING, AND PARTICIPANTS: The Adventist Health Study 2 (AHS-2) is a large, prospective, North American cohort trial including 96,354 Seventh-Day Adventist men and women recruited between January 1, 2002, and December 31, 2007. Follow-up varied by state and was indicated by the cancer registry linkage dates. Of these participants, an analytic sample of 77,659 remained after exclusions. Analysis was conducted using Cox proportional hazards regression, controlling for important demographic and lifestyle confounders. The analysis was conducted between June 1, 2014, and October 20, 2014. EXPOSURES: Diet was assessed at baseline by a validated quantitative food frequency questionnaire and categorized into 4 vegetarian dietary patterns (vegan, lacto-ovo vegetarian, pescovegetarian, and semivegetarian) and a nonvegetarian dietary pattern. MAIN OUTCOMES AND MEASURES: The relationship between dietary patterns and incident cancers of the colon and rectum; colorectal cancer cases were identified primarily by state cancer registry linkages. RESULTS: During a mean follow-up of 7.3 years, 380 cases of colon cancer and 110 cases of rectal cancer were documented. The adjusted hazard ratios (HRs) in all vegetarians combined vs nonvegetarians were 0.78 (95% CI, 0.64-0.95) for all colorectal cancers, 0.81 (95% CI, 0.65-1.00) for colon cancer, and 0.71 (95% CI, 0.47-1.06) for rectal cancer. The adjusted HR for colorectal cancer in vegans was 0.84 (95% CI, 0.59-1.19); in lacto-ovo vegetarians, 0.82 (95% CI, 0.65-1.02); in pescovegetarians, 0.57 (95% CI, 0.40-0.82); and in semivegetarians, 0.92 (95% CI, 0.62-1.37) compared with nonvegetarians. Effect estimates were similar for men and women and for black and nonblack individuals. CONCLUSIONS AND RELEVANCE: Vegetarian diets are associated with an overall lower incidence of colorectal cancers. Pescovegetarians in particular have a much lower risk compared with nonvegetarians. If such associations are causal, they may be important for primary prevention of colorectal cancers.

Vegetarian diets in the Adventist Health Study 2: a review of initial published findings.

The Adventist Health Study 2 is a large cohort that is well suited to the study of the relation of vegetarian dietary patterns to health and disease risk. Here we review initial published findings with regard to vegetarian diets and several health outcomes. Vegetarian dietary patterns were associated with lower body mass index, lower prevalence and incidence of diabetes mellitus, lower prevalence of the metabolic syndrome and its component factors, lower prevalence of hypertension, lower all-cause mortality, and in some instances, lower risk of cancer. Findings with regard to factors related to vegetarian diets and bone health are also reviewed. These initial results show important links between vegetarian dietary patterns and improved health.

Vegetarian dietary patterns and mortality in Adventist Health Study 2.

IMPORTANCE: Some evidence suggests vegetarian dietary patterns may be associated with reduced mortality, but the relationship is not well established. OBJECTIVE: To evaluate the association between vegetarian dietary patterns and mortality. DESIGN: Prospective cohort study; mortality analysis by Cox proportional hazards regression, controlling for important demographic and lifestyle confounders. SETTING: Adventist Health Study 2 (AHS-2), a large North American cohort. PARTICIPANTS: A total of 96,469 Seventh-day Adventist men and women recruited between 2002 and 2007, from which an analytic sample of 73,308 participants remained after exclusions. EXPOSURES: Diet was assessed at baseline by a quantitative food frequency questionnaire and categorized into 5 dietary patterns: nonvegetarian, semi-vegetarian, pesco-vegetarian, lacto-ovo-vegetarian, and vegan. MAIN OUTCOME AND MEASURE: The relationship between vegetarian dietary patterns and all-cause and cause-specific mortality; deaths through 2009 were identified from the National Death Index. RESULTS: There were 2570 deaths among 73,308 participants during a mean follow-up time of 5.79 years. The mortality rate was 6.05 (95% CI, 5.82-6.29) deaths per 1000 person-years. The adjusted hazard ratio (HR) for all-cause mortality in all vegetarians combined vs nonvegetarians was 0.88 (95% CI, 0.80-0.97). The adjusted HR for all-cause mortality in vegans was 0.85 (95% CI, 0.73-1.01); in lacto-ovo-vegetarians, 0.91 (95% CI, 0.82-1.00); in pesco-vegetarians, 0.81 (95% CI, 0.69-0.94); and in semi-vegetarians, 0.92 (95% CI, 0.75-1.13) compared with nonvegetarians. Significant associations with vegetarian diets were detected for cardiovascular mortality, noncardiovascular noncancer mortality, renal mortality, and endocrine mortality. Associations in men were larger and more often significant than were those in women. CONCLUSIONS AND RELEVANCE: Vegetarian diets are associated with lower all-cause mortality and with some reductions in cause-specific mortality. Results appeared to be more robust in males. These favorable associations should be considered carefully by those offering dietary guidance.