Breast cancer: Sentinel node biopsy

Sentinel node biopsy is a relatively new way of pinpointing the first few lymph nodes into which a tumour drains (called the "sentinel" node). This helps doctors remove only those nodes of the lymphatic system most likely to contain cancer cells. The sentinel nodes are the first place that cancer is likely to spread.

In breast cancer, the sentinel node is usually located in the axillary nodes, under the arm. In a small percentage of cases, the sentinel node is found somewhere else in the lymphatic system of the breast. If the sentinel node is positive, there may be other positive lymph nodes upstream. If it is negative, it is highly likely that all of the upstream nodes are negative.

How is the procedure performed?

To locate the sentinel nodes, a labelling substance, either radioactive tracer, blue dye or both is injected into the area around the tumour before a mastectomy or lumpectomy is performed. The tracer travels the same path to the lymph nodes that the cancer cells would take, making it possible for the surgeon to determine the one or two nodes most likely to test positive for cancer by either visualising the colour or using a hand held Geiger counter.

This method varies in how it is performed among hospitals and is still being tested to determine the best way to identify the positive nodes.

What are the advantages of this method?

Research suggests that the sentinel node biopsy procedure can be useful in determining which lymph nodes to remove, without the risk of complications associated with surgically removing all potentially cancerous nodes.

When a lumpectomy or mastectomy is performed, only a few lymph nodes are removed for laboratory analysis using the sentinel node biopsy technique. In traditional lumpectomy or mastectomy procedures, a greater number of the axillary nodes are removed, which can lead to complications after surgery such as lymphedema.