Breast cancer treatment and axillary (underarm lymph node) surgery have evolved over the years to become less extensive and more precise. Sentinel lymph node biopsy (SLNB) is now a standard method used to identify the first few lymph nodes that drain the breast and are most likely to contain cancer cells.

In some patients, breast cancer can recur in the same breast after the first surgery, known as ipsilateral breast tumour recurrence (IBTR). Managing the lymph nodes in such cases is challenging because prior surgery and radiotherapy may have altered the normal lymphatic drainage pathways. The standard treatment currently involves a complete axillary lymph node dissection (ALND), which can lead to higher rates of complications such as arm swelling (lymphedema).

This study, called the SLR study, aims to validate the use of a dual tracer technique (using a combination of radioactive tracer and blue dye) for identifying sentinel lymph nodes in patients with non-metastatic in-breast tumour recurrence who are undergoing repeat breast surgery. The study will also assess how lymphatic drainage pathways change after previous breast and axillary surgeries.

All eligible patients with confirmed non-metastatic breast cancer recurrence will undergo the dual tracer sentinel lymph node procedure, followed by standard axillary lymph node dissection. The study will evaluate the accuracy (false-negative rate) and identification rate of the repeat SLNB and will help improve understanding of lymphatic mapping in previously operated patients.

The results are expected to provide evidence on whether re-SLNB can safely replace full axillary clearance in selected patients and help reduce surgical morbidity while maintaining accurate staging.