A sentinel lymph node biopsy is a surgery that takes out lymph node tissue to look for cancer. A sentinel node biopsy is used to see if a known breast cancer or melanoma has spread from the original cancer site. A sentinel node biopsy may be done instead of a more extensive surgery called lymph node dissection. However, if cancer is found in the sentinel lymph node at the time of surgery, more surgery will be needed to remove additional lymph nodes.

The sentinel lymph node is the first node in a group of nodes in the body where cancer cells may move to after they have left the original cancer site and started to spread. For example, the sentinel node (SN) for breast cancer is normally one of the lymph nodes under the arm.

Your doctor injects a blue dye or special tracer substance or both into the area around the original cancer site. The dye or tracer moves to the first lymph node (sentinel node) that drains close to the cancer site. The dye or tracer makes a map pattern of lymphatic fluid. The map can show where the cancer is likely to spread and which lymph node is most likely to have cancer cells. Your doctor can see the dye or tracer with a special device. The lymph node can be taken out, cut into very thin slices, and looked at under a microscope at the time of surgery. If a sentinel node is positive for cancer cells, additional surgery is done to remove more lymph nodes.

Other tests, such as a culture, genetic tests, or immunological tests, may be done on the lymph node sample.

Why It Is Done

A sentinel lymph node biopsy is done to:

• See if a known cancer, such as breast cancer or melanoma, has spread to the lymph nodes.
• Remove a few lymph nodes instead of removing all the lymph nodes in an area. If the sentinel lymph node does not have cancer, this surgery takes less time, is simpler to do, and has a lower chance of long-term problems, such as ongoing arm swelling (lymphedema).

How To Prepare

Tell your doctor if you:

• Are or might be pregnant.
• Are taking any medicines.
• Are allergic to any medicines, including any anesthetics or dyes.
• Have had bleeding problems or take blood-thinners, such as aspirin or warfarin (Coumadin).
• Have had a biopsy in the past.
• Have had radiation treatment to the biopsy site.

Follow your doctor's instructions carefully. If you are given a medicine (sedative) to make you relax or sleep before the biopsy, do not eat or drink for 8 hours before the biopsy. Arrange for someone to drive you home after the biopsy.

Talk to your doctor about concerns you have regarding the need for the test, its risks, how it will be done, or what the results may mean. To help you understand the importance of this test, fill out the medical test information form.