AOPEP and breast cancer: Excluding women using HRT at baseline resulted in a reduction of breast cancer cases of up to 65% and diminished the associations of HDL-C, apo(a), and TG to non-significance but resulted in significant associations of TC with risk of breast cancer in similar strength to the associations within the full study population (Q4 vs. Q1, HRHDL 1.24, 0.85–1.80; HRapo(a) 1.19, 0.83–1.71; HRTG 0.73, 0.50–1.07; HRTC 0.65, 0.43–0.99).