Abstract P1-01-03: Interim analysis of the validation study on the clinical usefulness of the ICG fluorescence method for detecting sentinel lymph nodes in early breast cancer compared with the RI method (fICG-BR02)

Abstract

Abstract Background: Sentinel lymph node (SLN) biopsy guided by radioisotope (RI), blue dye or in combination methods is common. A high identification rate is reported for the RI-guided method. On the other hand, it has the demerits of radiation exposure, being expense, and it can only be used in a radiation-controlled area. The blue dye method, however, is safe and inexpensive, but the identification rate is lower compared with the RI method and requires training. The indocyanine green (ICG) fluorescent method involves the application of the fluorescing property. Lymph flow can be traced from outside the body with a photodynamic eye (PDE) camera simultaneously with an operation procedure. The ICG method is safe, inexpensive and requires little training, therefore its use will be widely permitted in any general hospitals. Recently, based on several retrospective clinical trials, the identification rate with the ICG fluorescent method has been reported to be equal to or greater than the RI method. The purpose of this multicenter study is to prospectively assess the diagnostic performance of SLN biopsy using the ICG fluorescence technique compared with RI. Materials and methods: In this validation study, the patients aged from 20 to 75 years-old with operable primary invasive breast cancer (cT1c-2N0M0) have been nominated and required the written informed consent. All candidates underwent SLN biopsy using the combined methods with RI and ICG fluorescence. The target sample size was 840 patients to evaluate the sensitivity of ICG method as a primary endpoint, and after 200 patients were enrolled we analyzed the identification rate and the SLN-positive rate of the RI and ICG methods respectively as the interim analysis planned beforehand. Results: Two hundred eligible patients were enrolled in this study from May 2011 to February 2012. Their median age was 53.0 years (range: 27-74 years). The number of patients with cT1c was 106 and that with cT2 was 94. The identification rate of the RI and the ICG method was 97% (194/200) and 96% (192/200) respectively. Of the 194 patients that were identified with the RI method, 186 (95.9%) were also identified with the ICG method. ICG identified 6 patients that were not identified by RI. On the other hand, RI identified 8 patients that were not identified by ICG. The SLN-positive rate was 25.5% (51/200). This rate was higher than we expected. Of the 51 patients with positive metastatic lymph nodes, 23 patients (21.7%) had cT1c breast cancer and 28 (29.8%) had cT2 breast cancer. The positive rate of the first SLN was 23.5% (47/200) and tumor cells skipped to the second or further tier in four cases (2%). Conclusions: The ICG-guided SLN biopsy procedure achieved a high identification rate almost equal to that with the RI method. Using this combination method, the identification rate was 100%. We will assess the sensitivity and the additive effect of combining the ICG fluorescence method with the RI method, etc., when all 840 patients have been enrolled (UMIN000005167). Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-01-03.