Technical aspects of the sentinel node biopsy in the EORTC AMAROS sentinel node trial.

Abstract

Abstract Abstract #1006 Background: The AMAROS trial is a phase III study comparing axillary lymph node dissection (ALND) with axillary radiation therapy (ART) in patients with proven axillary metastasis by sentinel node biopsy (SNB). The main objective of the trial is to prove equivalent locoregional control and reduced morbidity for ART. The aim of this interim analysis was to analyze the technical aspects of the SNB.
 Methods: The first 2000 patients with operable unifocal invasive breast cancer (5-30 mm) and clinically negative lymph nodes enrolled in the AMAROS trial between 2001 and 2005 were analyzed. The 26 participating institutions have been site visited as part of the surgical quality assurance. SNB is performed using preoperative lymphoscintigraphy, blue dye and a gamma-ray detection probe. Patients with a negative sentinel node were not subjected to ALND or ART.
 Results: The SN identification rate was 97% (range per institute 89%- 99%), 33% (n=658) of the patients were SNB positive, 62% (n=1245) were SNB negative and 2%(n=32) had other outcomes (non-axillary, missing data). Median two sentinel nodes were removed in the SNB positive as well as the SNB negative group. In 17% (344) of the patients, non-blue and non radio-active nodes were removed during the sentinel node procedure, median 1 node. In 11 patients, these nodes were the only tumor positive nodes found. In the SNB positive group the incidence of macro-, micrometastasis and isolated tumor cells was 61% (389), 26% (164) and 13% (80), respectively. In the ALND arm, further nodal involvement was seen 47,5% , 21,4 % and 16,7%, respectively. There was no correlation between the size of metastasis and the tumor size, grade or histological subtype. Of the sentinel nodes 59% (1907/3259) were radioactive and blue, 33% (1087/3259) were only radioactive, 8 %(265/3259) were only blue. Non-visualization on lymphoscintigraphy was seen in 7.6%(152), in 78%(118) of these cases a sentinel node was found during surgery. At least one sentinel node was located in the axilla in 89%(1777), in the internal mammary chain in 5% (104) and infra/supraclavicular in 1%(15). The injection site was intra/peritumoral in 53% subcutane/intradermal over the tumor in 9% periareolair in 16%, a combination in 4%, missing data 17%. Sentinel nodes in the internal mammary chain were significantly correlated with a intratumoral injection technique.
 Conclusions: These results indicate that with a 97% detection rate in this prospective international multicenter study using the combination of radioactive tracer and blue dye, the sentinel node procedure is highly effective. Differences in injection site affect the finding of non axillary sentinel nodes. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1006.