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Sentinel Node Biopsy

When breast cancer spreads, cancer cells are often found in the lymph nodes that are located under the arm, called axillary lymph nodes. The lymph nodes in this armpit region drain lymph from the breast and nearby areas. To determine if cancer has spread to a patient’s lymph nodes, the axillary lymph nodesare surgically resected in addition to removing part or all of the breast. In all, five to thirty nodes are surgically removed so they may be analyzed in a laboratory for evidence of cancer.

A sentinel node biopsy is an established alternative to axillary lymph node dissection. Molecular imaging is used to identify the first few, or sentinel, nodes into which a tumor drains. Sentinel nodes collect the fluid draining from the tumor and are most likely to contain cancer cells if the tumor has metastasized, or spread. In a sentinel node biopsy, only the sentinel nodes are surgically removed, which results in fewer complications and side effects for the patient, including lymphedema.

Prior to surgery to remove part of or the entire breast, a tiny amount of radioactive particles are injected in the area of the breast where the tumor is or around the nipple. Images may be taken to help the surgeon visualize the radiotracer’s ’s pathway as it leaves the breast. The surgeon makes an incision underneath the arm and passes a hand-held probe over the area to measure levels of radioactivity. Only the lymph nodes that have absorbed the radiotracer are removed. In less than five percent of sentinel node biopsies, the sentinel node cannot be identified and a full axillary dissection is done. 

Advantages of sentinel node biopsy

A sentinel lymph node biopsy is:

  • highly reliable in detecting cancerous cells
  • more accurate than the traditional axillary dissection in assessing whether breast cancer has spread to the lymph nodes. A negative sentinel lymph node indicates a greater than 95 percent chance that the remaining lymph nodes are also cancer-free
  • far fewer post-operative complications
  • performed on an outpatient basis
  • easier for the patient in terms of recuperation. Most patients resume regular activities within a few days and incisions generally heal within a few weeks.