Sentinel Lymph Node Biopsy
Sentinel node biopsy is a less invasive procedure and carries a lower risk of complications than axillary node dissection. The sentinel node is the first lymph node that filters fluid from the breast. Many cancer experts believe that malignant cells reach the sentinel node first and that this lymph node is most likely to contain cancer cells.
Based on this assumption, the node most likely to contain malignant cells should be removed and analyzed. If the sentinel lymph node is free of cancer cells, then it is highly unlikely that the other nodes are positive. This technique, combined with lumpectomy, is easily performed as an outpatient procedure and causes less pain and deformity than an axillary node dissection.
Sentinel node biopsy involves injecting a radioactive tracer and/or blue dye into and around the tumor. In some cases, a numbing medication (local anesthesia) or a sedative is administered prior to the tracer injection. When anesthesia is not used, patients may experience a burning sensation during the injection. With a small, hand-held Geiger counter, the surgeon tracks the path the tracer takes as it travels away from the breast and under the arm to the first lymph node. Once located, the sentinel node is removed through a small incision and sent to the laboratory for diagnosis.
If the results are negative, it is assumed that the cancer has not spread and there is no need for further surgery. If the sentinel node is positive, the surgeon may perform an axillary node dissection to assess how many other lymph nodes are affected.
The anesthesiologist must make sure that the patient does not have a history of allergy to the radioactive tracer or blue dye that is injected into and around the tumor.
Because sentinel node biopsy removes fewer lymph nodes than axillary lymph node dissection, many patients have no side effects. Pain, nerve damage, and lymphedema are more common when additional lymph nodes are removed with the sentinel node.
The blue dye may temporarily give the skin on the breast a bluish color. The radioactive material remains in the body for a short time (24–48 hours) and eventually dissipates. Some of it is eliminated in urine and stool and the urine may turn green for about 24 hours.
Most patients spend a day or less in the hospital after sentinel node biopsy.