Comstock 1997

Methods	Matched, nested case‐control study Country: US
Participants	Participants: number of participants n.r.; both genders Inclusion criteria: residents of Washington County Name of parent cohort: CLUE I and II Cohort Recruitment: 1974/75 or 1989 Outcome assessment: n.r. Number of cases: Lung cancer: 258 (male/female: 157/101) Case definition: incidence Years of follow‐up: n.r. Type of selenium marker: serum/plasma
Interventions	d.n.a.
Outcomes	Statistical methods: conditional logistic regression Variables controlled by matching: age, gender, race/ethnicity, year and month of sample collection, participant of Clue I or Clue II cohort
Risk estimates [95% CI]	Reference category: lowest quintile Results: Lung cancer   both genders: highest quintile: OR 0.65 (CI not reported)
Selenium levels in exposure categories	n.r.
Notes