Use of beta-blockers in patients with ductal carcinoma in situ and risk of invasive breast cancer recurrence: a Swedish retrospective cohort study.

Background: Retrospective observational studies suggest a potential role of beta-blockers as a protective strategy against progression and metastasis in invasive breast cancer. In this context, we investigated the impact of beta-blocker exposure on risk for progression to invasive breast cancer after diagnosis of ductal cancer in situ (DCIS).

Methods: The retrospective study population included 2535 women diagnosed with pure DCIS between 2006 and2012 in three healthcare regions in SwedenExposure to beta-blocker was quantified using a time-varying percentage of days with medication available.