Walter 2011

Methods	Cohort study Country: US
Participants	Inclusion criteria: aged 50 to 76 years, participants recruited from subscribers of commercial mailing list, residents of western Washington state, non‐whites excluded, no malignant disease at baseline Name of parent cohort: Vitamins and lifestyle (VITAL) study Recruitment: 1 October 2000 to 31 December 2002 Outcome assessment: 31/12/2008 Type of selenium marker: supplemental intake (questionnaire: use of supplements over the last 10 years, mean supplemental intake / day calculated) Case definition: incidence Number of cases: hematologic malignancies: 588
Interventions	d.n.a.
Outcomes	Statistical methods: cox proportional hazards regression, Variables controlled in analysis: sex, race/ethnicity (white, Hispanic, other), education (high school graduate or less, some college, college or advanced degree), smoking (pack‐years), self‐rated health (excellent, very good, good, fair, poor), vegetable servings per day (excluding potato servings); fruit servings per day; history of coronary artery disease (defined as history of heart attack, coronary bypass surgery, angioplasty, and/or angina; yes, no), history of rheumatoid arthritis (yes, no), history of fatigue or lack of energy over the year prior to baseline (yes, no), and number of first‐degree relatives with a history of leukemia or lymphoma (none, 1, 2)
Risk estimates [95% CI]	Reference category: none Results: highest level: RR 0.95 (95% CI 0.75 to 1.20)
Selenium levels in exposure categories	lowest level: none highest level: 20.1–400.0 mg/d
Notes