Stressful Life Events, Social Support, and Incident Breast Cancer by Estrogen Receptor Status.

Epidemiologic studies on the association between psychosocial stress and breast cancer risk remain inconsistent, while investigation of whether the association differs by ER status is limited. In this prospective cohort of postmenopausal women, high experiences of stressful life events were positively associated with ER-negative disease but not ER-positive.