Refining the optimal technical approach for sentinel node localization in breast cancer patients.

Abstract

In this issue of Annals of Surgical Oncology, Linehan and associates, of the Memorial Sloan-Kettering Cancer Center (MSKCC), provide readers with a study that compares 200 consecutive sentinel lymph node (SLN) biopsy procedures, all utilizing intramammary injection of blue dye, with intraparenchymal (IP) and intradermal (ID) lymphatic injection of radioisotope. The authors initiated this evaluation to determine the optimal method for selection of the SLN after objective criteria for accuracy of the localization process was determined. Since the introduction of the SLN biopsy by Cabanas in 1977, for staging of penile carcinoma, an accelerated interest in the clinical application of SLN has been credited principally to Morton et al.,1 who used this technique for melanoma of the trunk and extremities in 1992. Many reports followed about SLN that used blue dye,2 radioisotope localization,3 or an approach that used a combination of both.4 To date, 20 collective series have demonstrated the worth of the SLN biopsy and all data have been verified with Level I-II axillary lymph node dissection. Moreover, these various trials have further identified the accuracy of the SLN relative to other dissected nodes in 98% of cases (95%–100%) with a low falsenegative rate ( 6%) in most series, including the 2236 patients in the Linehan et al. series. As stated by the authors, no uniform technique was practiced among the various series, with the exception that the use of unfiltered isotope was the most common approach for radionuclide SLN identification. However, particle size, type, injection timing, total volume of the diluent for the radioisotope, site of the injection, single/ combination applications of the procedure, and ultimate operative approaches varied from institution to institution and even varied among investigators within the same institution. It is clear, however, when this many approaches that lack standardization continue to produce accurate identification 97% to 98% of the time, one cannot doubt the ability of SLN biopsy to correctly judge the histologic positivity/negativity of the sampled lymphatics. Thus, the current report has particular merit because the authors attempt to standardize the injection approach, as well as to simplify its application so that translational approaches for community surgeons will be reproducible with histological accuracy similar to that evident in the aforementioned series. The authors are to be congratulated for showing that the single isotope size and stratification of the applications of the IP injection of 0.3 mCi (11.1 mBq) in 4 cc of normal saline in 4 equal portions near the tumor did provide the desirable accuracy. Equally important is the observation that the ID injection of 0.1 mCi (3.7 mBq) (Group 2) had similar high localization success (100%) using the combination isotope plus dye technique. The approach for Group 2 was perhaps prompted by the favorable reports by Borgstein,5 who used ID injection of blue dye into the subareolar area of the breast, as well as the report by Veronesi6 where subdermal injection of isotope was used. The extensive experience at MSKCC with the ID injection of radioisotope for cutaneous melanoma prompted the design of the present study that was based on low-dose (0.1 mCi), low-volume (0.05 cc), single-site injection of unfiltered Tc99m/sulfur colloid proximal to, or overlying, the index tumor quadrant of the breast. The Linehan et al. study shows the ID injection for SLN to be superior to the IP route (97% versus 78%). Importantly, it shows that the uptake of radionuclide in the axilla occurs sooner and the shadow of surrounding radiation initiated by the injection site is more discrete and focused; this allows more accurate radiolocalization Received May 19, 1999; accepted June 1, 1999. From the Department of Surgery, Rhode Island Hospital, Providence, Rhode Island. Address correspondence to: Kirby I. Bland, MD, Department of Surgery, Rhode Island Hospital, 593 Eddy St., Providence, RI 02903; Fax: 401-444-6612. Annals of Surgical Oncology, 6(5):418–419 Published by Lippincott Williams & Wilkins © 1999 The Society of Surgical Oncology, Inc.