Pham TT, Hwang M, Lee ES, et al. - Researchers examined Korean women to evaluate the association between night-shift work (NSW) and breast cancer risk, as well as subtypes of breast cancer in this patient population. The study sample included 1,721 women with breast cancer and 1,721 female control participants. The investigators determined the subtypes of breast cancer based on estrogen, progesterone, and human epidermal growth factor receptor 2 statuses by reviewing pathology reports. They determined ORs for NSW experience, age at commencement of NSW, frequency, and duration, using conditional logistic regression and adjusted these for confounders such as parity and socioeconomic status–related factors. Among 1,721 pairs, engagement in NSW was reported for 10.58% of patients and 9.59% of controls. Observations revealed no correlation of NSW, which included long-term and heavy working exposure, with breast cancer risk.