||If the cause of
death was falsely attributed to prostate cancer in those patients with prostate cancer who
smoked, and since smokers are more likely to die, then more thorough ascertainment of
prostate cancer in smokers would have occurred. Screening for prostate cancer at baseline
may be less common in smokers than non-smokers, leading to elevated mortality from
prostate cancer due to a delay in treatment. The Health Professionals cohort study did
analyses which found that these two biases were unlikely to account for their results
(Giovannucci et al 1999).