What is a sentinel lymph node biopsy?

A sentinel lymph node biopsy is a surgical procedure that identifies whether cancer cells have spread beyond a primary tumour and into the lymphatic system. It is most commonly used when treating breast cancer and melanoma. 
 

Where are the sentinel lymph nodes located in the body?

The sentinel nodes are the first place in which cancer is likely to spread. In cases of breast cancer, the sentinel nodes are located under the arm in the axillary nodes. They may also be found in the lymphatic system of the breast. 
 

How is the procedure performed?

To locate the sentinel nodes, a substance such as a blue dye is injected into the area around the tumour before a mastectomy or lumpectomy is performed. The dye travels the same path that cancer lymph nodes would take, which enables the surgeon to determine the few nodes that are likely to test positive for cancer. 

An alternative option is for a weak radioactive solution to be injected into the area near the tumour, which is taken up by the lymphatic system and travels to the sentinel nodes in order to remove them. 
 

What might the results determine?

If the results from a sentinel lymph node biopsy don't show cancer, you won't have another lymph node evaluation. If you do need further treatment, your specialist will use the biopsy results to determine a treatment plan. If the sentinel nodes do contain cancer, your doctor may want to remove more to see how many are infected. 
 

Are there any risks to a sentinel lymph node biopsy?

A sentinel lymph node biopsy is generally a safe procedure. All procedures carry a small risk, but with a biopsy, these may include:
 

• Bleeding
• Bruising where the biopsy occurred
• Infection
• Allergic reaction - to the dye that was used
• Lymphoedema - which leads to a build up of fluid and swelling in the body.