Fig. 6
Forest plot for the association between ever smoking and prostate cancer. DM, diabetes mellitus. a Rohrmann et al. [49] had two sub-populations. b RR and 95% CI were calculated using frequency distributions or risk estimates and 95% CIs in subgroups. c RR and 95% CI were converted from HR and corresponding 95% CI using the formula RR ≈ (1-e HR x ln (1−P0))/P0 (P0 refers to the incidence rate of PCa in the control group). d Weights were from random effects analysis. e Onitilo et al. [68] had two sub-populations