Feasibility of sentinel lymph node biopsy omission after integration of F-18-FDG dedicated lymph node PET in early breast cancer: a prospective phase II trial

Objective: Sentinel lymph node biopsy (SLNB) is currently the standard of care in clinically node negative (cN0) breast cancer. The present study aimed to evaluate the negative predictive value (NPV) of F-18-FDG dedicated lymph node positron emission tomography (LymphPET) in cN0 patients. Methods: This was a prospective phase II trial divided into 2 stages (NCT04072653). In the first stage, cN0 patients underwent axillary LymphPET followed by SLNB. In the second stage, SLNB was omitted in patients with a negative preoperative axillary assessment after integration of LymphPET. Here, we report the results of the first stage. The primary outcome was the NPV of LymphPET to detect macrometastasis of lymph nodes (LN-macro). Results: A total of 189 patients with invasive breast cancer underwent LymphPET followed by surgery with definitive pathological reports. Forty patients had LN-macro, and 16 patients had only lymph node micrometastasis. Of the 131 patients with a negative LymphPET result, 16 patients had LN-macro, and the NPV was 87.8%. After combined axillary imaging evaluation with ultrasound and LymphPET, 100 patients were found to be both LymphPET and ultrasound negative, 9 patients had LN-macro, and the NPV was 91%. Conclusions: LymphPET can be used to screen patients to potentially avoid SLNB, with an NPV > 90%. The second stage of the SOAPET trial is ongoing to confirm the safety of omission of SLNB according to preoperational axillary evaluation integrating LymphPET.