Axillary lymph node status is Ihe most important factor determining treatment, recurrence, and

overall survival in breast cancer. The gold standard for examination of Ihe axillary lymph

nodes is surgical dissection followed by pathological investigation. The morbidities associated with complete removal of the axillary lymph nodes include lymphedema, sensory disturbances, limited arm mobility and seroma formation. The majority of lymph node dissections show no metastasis and can be considered superfluous retrospectively (Braems et af., 2008). There is an urgent need for markers to identify a subgroup of patients at low risk

of axillary lymph node metastasis who could avoid removal of axillary lymph nodes. Our group

recently found that the presence of small GTPase Rab278, a major driver of exosome release, significantly associates with lymph node metastasis in human breast cancer samples

(Hendrix et al., 2010a). Tumor·derived exosomes. secreted small membrane vesicles (30-100

nm) which contain numerous proteins, lipids and nucleic acids, are instrumental for the

development of a landing dock for future metastatic colonization. An integrated approach

using fresh collected tumor specimens, xenopatient models, biochemical-histopathological

analysis and clinical evaluation will be implemented to discover insights in exosome-packaged biomarkers that identify patients at low risk 01 axillary lymph node metastasis and

for whom lymph node dissection could be avoided. Exosome staging lor the prediction of

lymph node metastasis would have a huge impact on the life quality of breast cancer patients

and would benefit current health economics.