Observation or standard axillary dissection after sentinel-node biopsy in breast cancer: Final results from the German KISS study.

1012 Background: Although widely applied, data from randomized trials on long-term results after a sentinel node biopsy (SNB) approach in early breast cancer (BC) are still limited. The KISS study is a large prospective randomized phase III trial performed in 33 German centers, which had completed a training program before recruiting patients (pts). Methods: 1182 pts with operable, clinically node negativ, invasive breast cancer were equally randomized to either a strategy of standard axillary dissection (SAD) independent of the SNB finding (SAD arm, n=594), or to a strategy of performing SAD only in case of a positive SNB finding or failure of SN detection (control arm, n=588), but observation only in pts with negative SNB. Patients were stratified according to center, age and tumor size. The trial was designed to exclude an absolute difference in relapse-free survival (RFS) of 5% after 5 years (y) with sufficient confidence. Logrank tests were used to compare RFS (primary endpoint) and overall survival ...