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The Melanoma Patient and Sentinel Lymph Node Biopsy
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Submitted By: Vincent M. Cimmino, M.D.
Article by Vincent M. Cimmino, M.D
Clinical Associate Professor of Surgery;
Division of Surgical Oncology
University of Michigan Comprehensive Cancer Center
Introduction
The incidence of cutaneous melanoma has shown an alarming increase in recent years. There are many theories attempting to explain why physicians are seeing so many new cases. One of the most popular explanations pertains to the increased exposure to ultra-violet rays because of the continuing destruction of the ozone layer. Regardless of the reason there is controversy over the optimal surgical management of patients with disease that appears to be limited clinically to the skin. This means that there is no obvious spread of the tumor to another area. Typically the first area of metastasis (spread) is to the closest lymph nodes that drain the primary site. This becomes important since the status of the lymph nodes is the strongest predictor of relapse and survival.
There has been significant controversy over how these lymph node basins should be managed. The depth of the primary cutaneous melanoma plays a most important role in the management of the lymph nodes. It is important to remember that, in general, melanomas with a Breslow’s depth (the exact depth in millimeters from the skin surface to its deepest point) of less than 1 mm, do not require any treatment of the nodes. That is unless, there is a lymph node that can be felt or one that has proven to have melanoma present in it. Lymph nodes are collections of lymph tissue that are connected to tiny lymph vessels. It is along these vessels that tumor cells may travel and collect in the lymph nodes. The lymph nodes are important because in general they are the strongest predictors of relapse and survival.
Elective Lymph Node Dissection (ELND)
Many studies have suggested that removal of all lymph nodes in a region that drains the melanoma whether they have tumor, or not, may improve the patients’ survival rather than waiting until there is a proven lymph node with tumor in it and then removing all the regional lymph nodes. Most surgeons because of the small benefit and the chance of developing post –operative limb edema (swelling), however, have abandoned this idea.
Sentinel Lymph
Node Dissection
Recently, an alternative to ELND called sentinel lymph node dissection (SLND) was developed. This is a technique, which allows for the detection of the first lymph node or nodes that drain a particular tumor site. With some exceptions the sentinel lymph node is routinely used in patients whose primary melanoma is greater that 1mm in depth. It was proposed so physicians could detect an early site of spread to those nodes. If the nodes are negative for the tumor then there is only a 1%- 2% chance that other nodes are positive. This technique incorporates the use of radioactive material, which is injected at the melanoma site followed by performing of lymphoscintigraphy (a picture) to identify the drainage route and first lymph nodes that drain that site. A second modality is used combining the radioactive material with blue dye. This dye is injected in the skin around the tumor site just prior to beginning the operation. A hand held radiation counter is used to determine where the lymph nodes with the highest radiation concentration are located. The combination of the two modalities increases the surgeon’s ability to detect the sentinel lymph node(s). If a sentinel lymph node comes back positive for melanoma cells then a complete removal of all the lymph nodes in the area is necessary. This is done to determine how many lymph nodes are positive and is a predictor of long- term survival.
Figure 1. Injection of blue dye into the skin surrounding a melanoma
on the back.
Figure 2. Equipment used for lymphatic mapping. A hand-held
probe is connected to a gamma counter. Blue dye is injected with a
syringe.
Figure 3. Small blue stained lymphatic vessels leading
to a blue stained lymph node.
Advantages
Some of the advantages to SLNB in malignant melanoma include:
1) A negative SLNB will reduce the amount of surgery and
the complications of a complete elective lymph node removal.
(2) A positive SLN can be considered a staging procedure that
leads to a complete removal of the local lymph nodes and also treatment with the proper drugs (interferon alpha- 2b)
3) A negative SLNB may reassure the patient that the
likelihood of spread of the tumor is low.
4) If there is a pathway of the spread that is other than that
expected, it will be identified.
An added feature of SLNB mapping is the technique by which the lymph nodes are processed. The old technique of simple staining could often miss small areas of spread to a lymph node. Currently we employ a new method which allows for multiple sections of the nodes and identification of small areas of spread that heretofore went unrecognized.
Complications
The complications of SLNB include:
1) Wound infection (0.5- 1%)
2) Collection of fluid in the wound (3- 5%)
(seroma or hematoma)
3) Swelling of the arm or leg (associated with the
biopsy site) which is rare (0.5%)
4) Allergic reaction to dye (1.5- 2%)
Summary
SLN is highly accurate in determining if the lymph nodes are involved with spread from the primary cutaneous melanomas. It should be considered a standard approach provided surgeons, nuclear medicine physicians, and pathologists are adequately trained. If done correctly, it allows 80% of patients with melanoma to be spared a formal lymph node dissection (removal of all nodes in an area). This potentially avoids the usual complications associated with the procedure.
Published online May 2002
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Additional Authors: |
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Works Cited: |
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1. Leong Stanley P.L. The roles of sentinel lymph nodes in malignant melanoma.
Surgical Clinics of North America 2000; 80(6): 1741- 57
2. Clary BM, Brady MS, Lewis JJ, Cort DG, Sentinel lymph node biopsy in the management of patients with primary cutaneous melanoma: review of a large single-institutional experience with an emphasis on recurrence. Annals of Surgery 2001; 233 (2): 250- 8
3. Bostick P, Essner R, Glass E, et al. Comparison of blue dye and probe-assisted
Intraoperative lymphatic mapping in melanoma to identify sentinel nodes in 100 lymphatic basins. Arch Surg. 1999; 134; 43-49
4. Gershenwald JE, Thompson W, Mansfield PF, et al: Multi-Institutional melanoma lymphatic mapping experience: The prognostic valve of sentinel lymph node status in 612 stage I or II melanoma patients. J. Clin Oncol 17 (3): 976- 983, 1999
5. Leong SPL, Habb FA, etal: Optimal selective sentinel lymph node dissection in
in primary malignant melanoma. Arch Surg 132: 666- 673, 1997
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