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Sentinel Lymphadenectomy

Axillary Sentinel Lymphadenectomy for Breast Cancer

This new technique is slowly emerging as a choice for patients whose surgical protocol requires a standard axillary dissection. The theory behind this technique was introduced by several authors who postulated that when a sentinel axillary lymph node (or first node in the lymphatic drainage path) can be identified it correlates with the status of the rest of the lymph nodes of the axilla. The validity of this theory was affirmed by Reintgen et al. who noted the significance of the following conclusion. An axillary lymph node can be identified in 92% of the patients with breast cancer using combined dye and scintigraphic mapping techniques. In addition, a sentinel lymph node will be found positive (with metastatic tumor) in all patients with axillary invasion, and a negative sentinel lymph node equates to an axilla negative for tumor invasion. One of the positive aspects of a sentinel lymphadenectomy is that it will eventually eliminate most of the morbidity associated with standard axillary dissection.

NOTE: Although many surgeons are increasingly using this technique as a staging procedure, in 1997 it has not yet become a well accepted procedure. It is usually done with the support of an experienced nuclear medicine department. Finally, it should be stressed that standard axillary lymphadenectomy remains the standard of care for staging patients with Stage I, II and III breast carcinoma. If the following protocol is used all the risks and benefits of this protocol should be carefully disclosed to the patients.

  • The Technique

There are two methods or two mapping procedures to identify an axillary sentinel lymph node. 1) Vital Blue dye technique and 2) Filtered technetium-lable sulfur colloid (scintigraphy). Some authors have used the combination of both mapping techniques to increase the accuracy of their identification of the sentinel node. This is the technique found to be the most accurate and sensitive (1,2).

  • LYMPHAZURIN 1% (Isosulfan Blue - Vital Blue Dye)

Comes in a Lymphatic Mapping Procedure Pack*(USSC) or in single injection vial. Usual injection is 3 ml per tumor site. This dye (sterile acqueous solution) is classified as an inert physiological dye and has no known pharmacological action.

  • The NEOPROBE 1000™ (Portable Radioisotope Detection Device) or equivalent

  • Indications

All patients requiring an axillary dissection for staging purposes. This includes patients requiring a lumpectomy with axillary dissection followed by radiation treatment or a patient requiring a standard modified radical mastectomy (Stage I, II and III).

If feasible, the diagnosis of carcinoma should be made preoperatively with a FNA (3,4). This is considered an appropriate and accurate method to obtain a histological diagnosis. Patients with medial lesions of the breast should be excluded as well as patients whose lesions cannot be accurately diagnosed.

Some authors are now injecting the tumor or biopsy site in patient who have previously undergone a lumpectomy or incisional biopsy and then performing the sentinel lymphadenectomy.

  • Overall Protocol

This protocol labeled SNL is designed to obtain a diagnosis prior to performing the excisional biopsy, lumpectomy or mastectomy. This is usually done by FNA or core biopsy.

Another alternative is to inject the lesion, perform the lumpectomy, and if the lesion is malignant proceed with the SNL.

The Technique for SNL

  • STEP 1: The Tracer Injection

This technique uses a combined injection of 3 ml or 1% Vital Blue Dye (Isosulfan Blue) and 5 cc of Standard Concentration Technetium-labeled sulfur colloid (1).

Nonpalpable lesions are localized and the needle is left in place with the wire.

The radio-labeled tracer is injected around the tumor two to four hours prior to the procedure using this localization needle or by direct injection. Approximately 400 to 450uCi should be injected in the periphery of the tumor.

The vital blue is injected in the periphery of the tumor approximately 15 minutes prior to the procedure or using the localization needle.

NOTE: Increasingly, some surgeons are using this technique for patients who have previously undergone a lumpectomy. In these cases, the periphery of the biopsy/lumpectomy site is injected. The surgeon should be careful not to inject the center of the cavity which in many cases will remains cystic (seroma) for weeks.

  • STEP 2: Mapping and Identifying the Sentinel Node

1. Locating the highest concentration point of the Radio-tracer: A hand held gammadetection probe (Neoprobe 1000, Neoprobe corp., Dublin, Ohio) is used to identify the injected site ( highest count - over 15000), then the focus of highest activity in the axilla prior to making the incision.

2. Making the Skin Incision: the skin incision is made over this area (3-4 cm in size). The axilla is entered very carefully and the afferent blue stain lymphatic channels are identified and tracted to the sentinel lymph nodes. The sentinel lymph nodes are identified.

3. Confirmation of the SNL location: The nodes stained blue are removed. Tracer activity records are performed. First, control background readings are taken (over non Sentinel Node Areas in the Axilla). Secondly, ratios of potential sentinel nodes versus non sentinel nodes are taken. Ratio over 10 confirms the area contains a sentinel node. Thirdly, the resection bed is checked. If the activity is at least 1.5 time greater than the recorded background reading, the search for additional sentinel nodes should be continued.

4. Labeling the sentinel nodes: The resected sentinel nodes should be resected and labeled appropriately.

  • STEP 3: Performing the Lumpectomy or Total Mastectomy

The total mastectomy or the lumpectomy should be then performed. The lumpectomy can either be done as a formal surgical lumpectomy or by using the ABBI.

Technical Problems

-The Shine Through Phenomenon: As reported by Albertini et al. this occurs when the original activity site or the tumor is too close to the axilla thus interfering with the axillary reading of the radiolabeled tracer. In these cases the lumpectomy or mastectomy may have to be first performed to eliminate this interference.

-Inner Quadrant Tumors: Inner quadrant tumors are not amenable to sentinel node lymphadenectomy for obvious location reasons. The lymphatic drainage of these tumors is usually via the internal mammary nodes.

-Lymphatic Node Skipping Tumor Progression: There has been numerous concerns about skipped metastasis. Some authors have claimed it occurs in 15% of the cases. Albertini et al. in their study shows this does not affect the sentinel node mapping.

-Cystic/seroma center of biopsy and lumpectomy site: Patients who have undergone a previous excisional biopsy or lumpectomy most often will have a post-operative seroma at that site. The surgeon should be meticulous not to inject to tracer or dye in this seroma. The seroma will trap the tracer and dye and will invalidate the study. Instead, the borders of the llumpectomy site should be injected.

Results

Localization of the sentinel node can be achieved in 65% of the cases using the Blue dye only and in 71% (1) to 97.5% (5) of the cases using the radiolabeled colloid. In some studies, when the combination of both techniques is used a localization rate up to 92% is achieved (1).

Performing a sentinel lymphadenectomy for patients requiring appropriate staging with an axillary dissection will decrease the morbidity of the procedure and will truly make this procedure a minimally invasive lymphadenectomy staging procedure.

Most authors are now recommending patients found to have a negative sentinel lymph node should have no further axillary dissection. On the other hand, there is no real consensus on how to handle patients with a positive sentinel lymph node, i.e., should they or should they not undergo a formal axillary dissection assuming the axillary staging has been completed.

References

  • 1. Reintgen et al: Sentinel Lymph Node Sampling Accurately Stages Breast Cancer . JAMA 1996: 276:1818-1822.
  • 2. Guliano AE et al. Lymphatic mapping and sentinel lymphadenectomy for breast cancer. Ann Surg. 1994; 220:391-401.
  • 3. Wanbo et al: Fine needle aspiration cytology in lieu of open biopsy in the management of primary breast cancer. Ann Surg. 1984; 199;569-579.64-1867.
  • 4. Leong SP et al. Optimal selective sentinel lymph node dissection in primary maligant lymphoma. Arch Surg: 1997; 132 666-673
  • 5. Albertini JJ et al: Lymphatic mapping and snetinel node biopsy in patients with breast cancer. JAMA 1996-276,22:1818-1822
  • 6. Giuliano A et al: Sentinel Lymphadenectomy for Breast Cancer. J Clin Onc1997:15:2345

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