Point estimates and 95% confidence intervals for differences in PSA trajectories of the 200 μg/d selenium (circle) and 800 μg/d (square) selenium treatment groups as compared with placebo (reference) stratified by quartiles of baseline selenium. Point estimates and 95% confidence intervals for differences in PSA trajectories of the 200 μg/d selenium (circle) and 800 μg/d (square) selenium treatment groups as compared with placebo (reference) stratified by quartiles of baseline selenium. Models were adjusted for age, BMI, race, Gleason score, pack-years of smoking at enrollment, baseline PSA, and type of assay used to estimate PSA. Confidence intervals crossing zero indicate no statistically significant difference at P = 0.05. Regression coefficient is for the interaction term between years on study and treatment group. M. Suzanne Stratton et al. Cancer Prev Res 2010;3:1035-1043 ©2010 by American Association for Cancer Research