No curative therapies exist for recurrent breast cancer, which includes metastasis (the spread of cancer to distant sites). A minority (up to 15%) of breast cancer patients will suffer recurrence, which may manifest up to 15 years after initial diagnosis. Because it is not yet possible to accurately predict which patients will relapse, the large psychological burden of an uncertain future is shared by all.

Recurrence is a major obstacle in the management of breast cancer and is thought to arise from dormant disease that had already spread and evaded the systemic therapy at time of the primary cancer. Understanding and targeting dormant tumour cells to combat cancer progression is a major clinical challenge in breast cancer.

Epithelial mesenchymal plasticity (EMP) refers to a collective of changes and behaviours of cells in the body that allow the cells to, temporarily or stably, alter their characteristics. EMP are the molecular and cellular processes that change stationary epithelial cells in structured, well defined environments into adaptable mesenchymal cells that can survive with limited cell-cell adhesion, migrate and invade new environments, and vice versa. The ability of breast cancer cells to switch between, and combine, epithelial and mesenchymal phenotypes relates to many aspects of breast cancer progression, including resistance to systemic therapy. EMP characteristics have been identified in the highly malignant breast cancer stem cells that underpin metastasis and fuel recurrence, and in tumour cells found in the blood stream and bone marrow of breast cancer patients more likely to suffer recurrence. These cells (the circulating tumour cells (CTC) in the blood and the disseminated tumour cells (DTC) in the bone marrow) may be dormant tumour cells involved in recurrence. The involvement of EMP in critical aspects of breast cancer has led to the establishment of the EMPathy Breast Cancer Network (EMPathy BCN) with its focus on EMP as a timely and novel opportunity to further the advances in combating breast cancer.

The EMPathy BCN is seed-funded by the National Breast Cancer Foundation (NBCF) and receives grant moneys from various other major agencies. Its goals, which are fine-tuned through community engagement, include the integration of EMP assessment in DTC and CTC into breast cancer clinical trials, the development of improved breast cancer diagnostics that predict response to therapy and the likelihood of recurrence, and the development of agents targeting EMP as therapeutics for recurrent breast cancer.