Unmet challenges in systemic therapy for early stage breast cancer

Despite marked progress in outcomes for women with early stage breast cancer, unmet challenges persist. These include accounting for the cohort of tumors that do not have favorable clinical outcomes related to tumor heterogeneity, particularly the variation within the subset of ER positive breast cancer; better treatments for subsets where existing therapies are not fully effective; and the development of biomarkers to predict response or need for ongoing treatment. Beyond these tumor-related factors, there is persistent need for focus on improving the patient's experience of treatment e avoiding unnecessary therapy, and providing better supportive care so as to minimize side effects and social and economic disruption caused by treatment. For clinical investigators, the improved prognosis for early stage breast cancer has meant that large sample sizes of subjects are needed for prospective clinical trials with cancer outcome endpoints. As a consequence, the scale of clinical research enterprises has become enormous, too often unsupportable without industry or government resources. Finally, as breast cancer is a global health concern, there is an urgent need to assure that screening and treatment are available to women around the world so that the progress achieved in developed countries can reach billions of women everywhere on earth. (C) 2021 Published by Elsevier Ltd.