Breast cancer is the most common cancer in American women, with 180,000 new cases diagnosed yearly. Two-thirds of these are “early cancers”, with no spread of cancer outside the breast and a high cure rate. Axillary lymph nodes are the most common site of spread for breast cancer. The presence or absence of lymph node involvement is the single best predictor of outcome, and of the need for chemotherapy.

Physical exam and x-rays do not reliably predict lymph node involvement. Traditionally this has been determined by surgical removal of most of the lymph glands under the armpit, and analysis of the tissue by a pathologist.

However, there can be problems associated with this surgery such as pain, and swelling (lymphedema) of the arm, and in early stage breast cancers often no cancer is present in the lymph glands. A new technique is now available which allows analysis of those lymph nodes at greatest risk for spread, known as sentinel nodes. This minimizes the extent of surgery, allowing faster recovery and shortened hospitalization. This technique, by focusiong on the lymph gland at greatest risk for spread, also allows the pathologist to meticulously analyse the lymph node, using special stains, and has been demonstrated to be a more accurate assessment for metastases.

The sentinel node is defined as the first lymph node draining a cancer, and is identified during surgery after the injection of a radiolabeled tracer (technetium-99m labeled sulfer colloid), and colored dye (isosulfan blue) around the cancer. Often, the surgery can be performed in Day Surgery as an outpatient. Originally used in the evaluation of malignant melanomas, the technique was first applied to breast cancer in the mid-1990’s, and the extensive available literature now concludes that in experienced hands there is a very high rate of sucessful identification of the node. Furthermore, precise and extensive evaluation of the sentinel axillary lymph gland by pathologists using both standard methods of microscopic analysis, as well as special stains specific for breast cancer, allows for an in-depth analysis of the sentinel lymph node, not previously available for standard pathologic evaluation of lymph nodes.

Sentinel lymph node evaluation offers additional advantages over the older standard lymph node dissection. Unlike lymph node dissection, sentinel node procedures do not disrupt the lymphatic channels of the breast and axilla, which can result in lymphedema. Other side effects of axillary lymph node dissection, such as temporary limitation of range of motion of the arm, possible fluid collections (seromas) in the axillary surgical site, and post-operative pain are minimized.

Why do we still need surgical evaluation of the axillary lymph nodes? As stated above, the presence or absence of breast cancer in the lymph nodes is the single most important predictor of survival. While other, non-surgical techniques such as MRI, pet-scans, mammography and ultrasound are not currently sensitive enough to predict the presence or absence of cancer cells in the lymph nodes. Physical examination is also inaccurate, and cannot be depended upon to rule-out metastatic disease in the lymph nodes.

While originally used in the setting of breast conservation, the sentinel node technique can be used in selected cases when mastectomy is the necessary or chosen intervention, as discussed with your surgeon.