Breast Cancer Research is excited to present a curated collection on how different lifestyles, health, and populations are linked to breast cancer. Edited by one of our Deputy Editors, Dr. Leslie Bernstein is a leading epidemiologist in identifying physical activity as a means to reduce the risk of breast cancer. Dr. Bernstein would like to draw attention to two publications that come to different conclusions about the historical use of low-dose aspirin: one by Christina A. Clarke et al. and the other by Gabriella Frisk et al. We invite the reader to consider the study design and questionnaire of each cohort as well as the broader challenges of epidemiological studies. Other seminal research included in the collection is the association of breast cancer with habits such as smoking and nighttime eating as well as environmental factors such as traffic noise and air pollution.