Smoking and risk of amyotrophic lateral sclerosis: a pooled analysis of 5 prospective cohorts.

Background: Cigarette smoking has been proposed as a risk factor for amyotrophic lateral sclerosis (ALS), but epidemiological studies supporting this hypothesis have been small and mostly retrospective.

Objective: To prospectively examine the relation between smoking and ALS in 5 well-established large cohorts.

Design: Five prospective cohorts with study-specific follow-up ranging from 7 to 28 years.

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.

Smokeless tobacco use and the risk of Parkinson's disease mortality.

We examined the association between smokeless tobacco use and Parkinson's disease (PD) mortality as assessed by death certificate in a prospective cohort of 95,981 never-smoking men. In this cohort, smokeless tobacco use is inversely associated with PD mortality, with an age-adjusted risk of 0.22 (0.