Highlights of the San Antonio Breast Cancer Symposium 2019 Part 2: the challenges of tumor heterogeneity

The 42nd annual San Antonio Breast Cancer Symposium (SABCS) was convened in San Antonio Texas on December 10 – 14, 2019. More than 7000 clinicians and scientists from around the world participated in the symposium which featured a range of presentations and keynote talks pertaining to breast cancer screening, prevention, loco-regional and systemic therapies. This two-part report highlights a selection of important studies presented at this premier breast cancer event with the second part discussing a range of topics including extended hormonal therapy, capecitabine for partial responders after neoadjuvant chemotherapy (NACT), anti-HER2 therapies and immunotherapy with checkpoint inhibitors.