Until recently, a patient with breast cancer usually underwent precautionary removal of her surrounding lymph nodes in combination with the removal of her cancer by mastectomy (removal of the breast) or lumpectomy (removal of only the palpable cancer lesion within the breast).
Lymph nodes are organizing areas for the body's infection-fighting white blood cells. They also, however, act as depots for the early spread of cancers like breast cancer. The removal of lymph nodes is called axillary dissection, named for the lymph nodes' location under the armpit, or axilla. Axillary dissection enables the surgeon to determine whether the patient's cancer has spread into surrounding lymph nodes.
The procedure carries a high risk of complications, such as pain, infection, difficulty with arm movement, and, most seriously, chronic swelling of the arm, a condition called lymphedema. Lymphedema occurs in 10 percent to 20 percent of all women who undergo axillary dissection.
Surgeons can now determine whether cancer has spread into surrounding lymph nodes by removing just one node: the sentinel node. The sentinel node is the first node into which the lymph system drains.
If, after removal and examination, the sentinel node is discovered to be free of cancer, then cancer probably has not spread into the rest of the lymph nodes. Further lymph node dissection is unnecessary. Studies show a better than 90 percent accuracy rate with sentinel node biopsy. Sentinel node biopsy allows for an accurate assessment of the spread of cancer into the lymph nodes while lessening the risk of complications and reducing pain.
Information from sentinel node biopsy helps to determine the extent of a patient's cancer as well as the patient's prognosis, key information for determining future treatment.
Sentinel lymph node biopsy has been best studied in the cases of early stage breast cancers with smaller tumors and lower risk of spread to the lymph nodes. It is not the standard of care in later stage cases with a higher risk for spread to axillary lymph nodes.
It is very important that the surgeon performing the sentinel lymph node biopsy is a breast surgeon with considerable experience performing the sentinel lymph node biopsy. The accuracy of the procedure to predict spread to the axillary lymph nodes is critically dependent on the experience of the surgeon.
Aside from routine precautions appropriate for any surgery, there are no special instructions for the patient about to undergo sentinel node biopsy. As the patient is prepared for surgery, the surgeon usually tells her about what will be taking place during the procedure. After the patient is placed under general anesthesia, the surgeon isolates and removes the sentinel node. While the biopsy (tissue sample) is being analyzed, the surgeon then performs the lumpectomy or mastectomy. In some cases, a port for administration of chemotherapy (cancer-killing drugs) may also be inserted while the patient is still in surgery.
If the patient is also going to receive chemotherapy to reduce tumor mass before undergoing a lumpectomy, sentinel node biopsy must be performed beforehand. Otherwise, chemotherapy might kill any cancer in the lymph nodes without its presence being first identified, dangerously skewing the prognosis.
If the results of the biopsy indicate there is no cancer in the sentinel node the patient most likely will be sent to recovery as soon as her other surgery is completed. If the results are positive for cancer, the patient should have a complete axillary dissection. This is performed either at the same surgery or at a subsequent surgery.
Most of the side effects of the procedure are short-lived. Common side effects include soreness, burning, a numb sensation in the affected area as well as a temporary bluish discoloration to the breast and sometimes in the urine.
Sentinel node biopsy offers a faster recovery time with less discomfort, less change in sensation. Some patients may still experience discomfort and some change in sensation.
Ongoing research on sentinel node biopsy is part of a cancer treatment movement that strives to marry the highest effectiveness with the least debilitating side effects.