Clinical:Case Study: Sentinel Lymph Node Identification

Original materials created in March 1999 by Patricia Dawson, M.D., Ph.D., FACS

Sentinel Node Biopsy

Axillary lymph node dissection has been considered essential to staging breast cancer patients, but carries a significant risk of complications,e.g.,lymphedema of the arm occurs in some patients.In the literature, lymphedema is estimated from 1% to 20% of patients who have axillary lymph node dissection. The actual incidence is difficult to establish since symptoms may occur many years after surgery.While most lymphedema is mild, some women develop significant arm and hand swelling. It is anticipated that less extensive axillary surgery will lower the incidence of lymphedema and improve post-operative recovery time.Lymphatic mapping and sentinel lymph node biopsy, with or without lymphatic mapping, are procedures that may provide staging information without the risks of a standard axillary lymph node dissection.

Sentinel Lynph Node Identification

The sentinel node is defined as the first node(s) draining the tumor in the regional lymphatic basin.This node is identified by combining preoperative nuclear medicine lymphatic mapping that uses technetium 99m sulfur colloid with intra-operative use of isosulfan blue. Sentinel lymph node biopsy has proven effective in staging patients with melanoma and is currently being evaluated, in multiple institutions,for breast cancer patients. Correlation studies have shown that the sentinel node can reliably predict the presence or absence of metastatic cancer in the regional lymph nodes. At this time, it is important for each institution performing sentinel lymph node biopsy to demonstrate the efficacy of the technique by their own surgeons and radiologists. In the study phase, patients who agree to participate will undergo both sentinel node biopsy and standard axillary dissection. When the institution and surgeons have at least a 90%concordance rate of axillary dissection results with sentinel node biopsies, they can offer sentinel node biopsies alone to their patients. Patients who have metastatic disease in the sentinel node will then be advised to have a standard axillary lymph node dissection. Those with negative sentinel nodes will be spared further axillary surgery. A few institutions have completed their correlation studies and offer patients sentinel lymph node biopsy alone.

Process

Patients who have sentinel lymph node biopsy will have either intraoperative identification of the node with blue dye, or a combination of preop nuclear medicine lymph node mapping with intraoperative blue dye. For the nuclear medicine mapping, a small amount of isotope is injected next to the breast mass or mammographic abnormality. The sentinel node is identified by gamma camera imaging and a mark is made on the skin over the sentinel node(s).

During surgery several cc’s of isosulfan blue are injected into the tumor bed to aid with visual identification of the sentinel lymph node.(In some patients this may result in transientskin and urine discoloration.) The sentinel node is then identified by tracing the blue dye stained lymphatics and by measuring the isotope activity with a hand-held gamma probe. The sentinel node is sent for pathology. In a correlation study procedure, the standard axillary dissection is done and lumpectomy or mastectomy is performed.

Unfortunately, pathologic analysis of the sentinel node cannot be done during surgery. If the sentinel lymph node contains tumor, the patient is advised to return for a standard axillary lymph node dissection. If the sentinel node is negative, no further axillary surgery will be required.

There is no additional risk to or morbidity for the patient related to the lymphatic mapping or sentinel node biopsy. Recovery is unaffected. Surgery time may be increased by about 20minutes. Because there is a small risk (1.5%) of allergic reaction (itching, hives, difficulty breathing) to isosulfan blue, it should not be used in patients with known allergies to these or related products. For patients in correlation studies, participating may be an advantage because sentinel lymph nodes can be studied more closely and a small increase in the number of metastases identified. While the study patients may not benefit directly, their participation will benefit future breast cancer patients.

Follow-up on the Patient

(For Part I of this case, please see In This Case February 1999)

To prepare for losing her hair, she got her hair cut short and purchased a wig. She has started her radiation therapy, and except for feeling fatigued, is not having any major problems with it. She has joined a support group for women with breast cancer and feels that it has made a big difference in her ability to cope with her diagnosis and the changes it has necessitated in her life. She has rearranged her priorities and is now taking more time for herself, to enjoy life, be with her family and friends, and to reflect on what is important to her. See “The gifts of cancer?” by Linda Ellerbee - The Seattle Post-Intelligencer, Sunday March 21,1993).

References

1. Cox, et. al., Guidelines for Sentinel Node Biopsy and Lymphatic Mapping of Patients with Breast Cancer. Annals of Surgery, 2217:645-53.
2. Gadd and Galper, Evolving Issues in the Management of the Axilla Including Sentinel Node Biopsy. Diseases of the Breast Updates. 1998;2:1-9.
3. McMasters, et. al., Sentinel Lymph Node Biopsy for Breast Cancer - Not Yet the Standard of Care. NEJM 1998;339:990-95.