Treat ER⁺ight: Canadian prospective observational study in post-menopausal HR⁺HER2^- advanced breast cancer women—First interim analysis (IA).

1067 Background: Treat ER+ight is the first Canadian real-world study enrolling patients (pts) previously exposed to NSAI therapy and currently receiving endocrine therapy (ET) alone or in combination with targeted therapy (ET+TT). Methods: This first planned IA describes baseline parameters and adverse event (AE) prevention strategies adopted by 16 centers since Feb 2016 upon enrolling pts initiating ET or ET+TT. Results: See Table.Conclusions: This IA suggests that pts initiating ET+TT are younger, have a better ECOG status, mostly visceral disease and receive more prophylactic/proactive AE prevention therapies. Insights into real-world dosing and sequence will be presented. Clinical trial information: NCT02753686. [Table: see text]