Androgen receptor (AR, a member of the steroid hormone receptor family) status has become increasingly important as both a prognostic marker and potential therapeutic target in breast cancer. AR is expressed in up to 90% of estrogen receptor (ER) positive breast cancer, and to a lesser degree, human epidermal growth factor 2 (HER2) amplified tumors. In the former, AR signaling has been correlated with a better prognosis given its inhibitory activity in estrogen dependent disease, though conversely has also been shown to increase resistance to anti-estrogen therapies such as tamoxifen. AR blockade can mitigate this resistance, and thus serves as a potential target in ER-positive breast cancer. In HER2 amplified breast cancer, studies are somewhat conflicting, though most show either no effect or are associated with poorer survival. Much of the available data on AR signaling is in triple-negative breast cancer (TNBC), which is an aggressive disease with inferior outcomes comparative to other breast cancer subtypes. At present, there are no approved targeted therapies in TNBC, making study of the AR signaling pathway compelling. Gene expression profiling studies have also identified a luminal androgen receptor (LAR) subtype that is dependent on AR signaling in TNBC. Regardless, there seems to be an association between AR expression and improved outcomes in TNBC. Despite lower pathologic complete response (pCR) rates with neoadjuvant therapy, patients with AR-expressing TNBC have been shown to have a better prognosis than those that are AR-negative. Clinical studies targeting AR have shown somewhat promising results. In this paper we review the literature on the biology of AR in breast cancer and its prognostic and predictive roles. We also present our thoughts on therapeutic strategies.

Inferior vena cava (IVC) filters, first introduced in 1998, have been utilized to reduce risk of pulmonary embolism (PE) in the setting of an inability to anticoagulate patients. The use of IVC filters has increased and continues to rise, especially with the introduction of retrievable IVC filters. Since their initial introduction, guidelines have been developed on the appropriate use of IVC filters. According to the American College of Chest Physicians (ACCP), the use of an IVC filter is limited to patients with an absolute contraindication to therapeutic anticoagulation or failure or complication of anticoagulation in the setting an acute proximal venous thrombus. Relative indications for IVC filter placement include high clot burden in setting of low cardiopulmonary reserve, high risk patients, or severe trauma without documented thrombosis. In 2010, the FDA announced a safety communication recommending removal of retrievable IVC filters due to reports of several adverse clinical outcomes associated with retained filters including thrombus formation, recurrent PE, filter migration, erosion or perforation through the IVC wall, and filter fracture with fragment embolization. In 2014, the FDA recommended removal of the IVC filter within 2 months after filter placement if the patient's risk of thrombosis had passed. In this retrospective analysis of IVC filter management, we reviewed indications for placement according to current guidelines as set by the ACCP, initiation of appropriate anticoagulation, complication rates, and retrieval rates. In addition, we compared the data prior to the FDA recommendations in late 2014 and data after the recommendations to determine if there was a change in practice. After reviewing 179 patients, 89 patients in 2014 and 90 patients in 2015, who underwent IVC filter placement, only 81% (N=145) of patients had appropriate indications for IVC filter placement and 30% (N=54) of patients had inappropriate anticoagulation after IVC filter placement, given as prophylactic dosing of low molecular weight heparin. A comparison of retrieval rates prior to and after the FDA warning, showed a 19% (60% in 2014 vs 79% in 2015) improvement in IVC filter removals. There was an 11% complication rate, mainly related to IVC filter related acute DVT or IVC occlusion. A root cause analysis specifically for inappropriate IVC filter placement and appropriate anticoagulation and determined that familiarity of the guidelines and non-evidence based recommendations from consultants were major factors. Based on the analysis, we next plan to utilize the electronic health record system to help clinicians understand indications and when to initiate appropriate anticoagulation, with the opportunity for hematology consultants to be involved in situations that do not clearly fit within published guidelines. Disclosures No relevant conflicts of interest to declare.