Jacob L, et al. - In women with breast cancer followed in gynecological practices in Germany, researchers examined the effect of sleep disorders on the development of metastases. This case-control study involved women who were initially diagnosed with breast cancer in Germany between January 2000 and December 2015 (index date). Participants in the study were 11,412 women. In women diagnosed with breast cancer in gynecological practices in Germany, a positive correlation was observed between sleep disorders and the presence of metastases.