Background: With the accumulation of RWD in healthcare, CER continues to expand. RWD are becoming increasingly relevant in oncology, particularly since the onset of care pathways and CMS’ Oncology Care Model pilot program; yet, CER in oncology presents several challenges as disease biology differs by cancer type and many RWD sources do not capture clinical response, progression or survival. This review examined common endpoints reported in RWD studies on CER and TxP in MBC, focusing on HER2-negative and Triple Negative (TN) MBC. Methods: PubMed (2006-January 2016) and 4 conferences (2011-January 2016)—ASCO and SABC meetings/symposiums—were searched using MeSH/keywords, e.g., metastatic breast cancer, treatment, and comparative effectiveness. RWD CER and TxP studies in U.S. patients with HER2-negative or TNMBC were included; clinical trials were excluded. Results: Of1,782 total records, 17 articles and 9 conference abstracts were included. Studies using RWD increased over time with 2 studies published in 2010, 1 in 2012, 6 in 2013, 6 in 2014, 10 in 2015, and 1 as of January 2016. Of these, 8 were CER and 18 examined TxP. Most studies were retrospective chart reviews (7 CER; 10 TxP studies), others were retrospective secondary database analyses (1 CER; 6 TxP) and physician surveys (2 TxP). RWD sources included commercial insurance claims, SEER-Medicare, and California Cancer Registry data. Nineteen studies reported results in patients with HER2-negative MBC and 7 reported in TNMBC patients. Primary endpoints included overall survival (OS), progression-free survival (PFS), and treatment duration (TD). CER studies most commonly reported TD and survival outcomes (e.g., OS, PFS), each reported in 75% of the studies. TxP studies also most commonly examined survival outcomes (61% of studies), in addition to various treatment patterns and duration outcomes. Conclusions: This literature review indicates that in parallel to the availability of RWD, published CER studies and analysis of treatment patterns have grown in the last 5 years. The most commonly reported outcomes include OS, TD and PFS.