Internal Mammary Sentinel Lymph Node Biopsy With Modified Injection Technique

Internal Mammary Lymph Node (IMLN) and Axillary Lymph Node (ALN) are regarded as "the first station" of lymphatic drainage in breast cancer, serving as an important reference for lymph staging and decision-making. Although the concept of Internal Mammary Sentinel Lymph Node Biopsy (IM-SLNB) has been included in the AJCC guidelines since the 6th edition, technical bottlenecks and clinical benefits still remained to be the main reasons limiting its clinical application: Technical bottlenecks: In previous clinical practice, the internal mammary visualization rate was very low (13% on average, 0% -37%) under the guidance of the traditional radionuclide injection technique, which became a technology bottleneck restricting the widespread of IM-SLNB. After continuous exploration, our center invented the "modified injection technique" of injecting the nuclide tracer into the mammary gland layer at 6 and 12 o'clock around the areolar under the guidance of ultrasound, as well as increasing the injection volume to increase the local tension. A high internal mammary imaging rate of 71% was obtained, which laid a foundation for the further study and clinical application of IM-SLNB. Clinical benefits: The IM-SLNB is a method to assess IMLN metastatic status in a minimally invasive way, which may improve the system of regional staging and guide precise IMLN treatment. However, based on the current IM-SLNB indication, the internal mammary metastasis rate was only 8%-15%, and it only had little influence on treatment strategy, which led to the controversy of its clinical application. Previous studies of extended radical mastectomy showed that in ALN positive patients the IMLN metastasis rate was 28-52%, while in ALN negative patients the metastasis rate was only 5-17%. Therefore, the continuation of the previous A-SLNB indication (clinical ALN negative) to IM-SLNB is apparently not in line with the current clinical practice, but further evaluation of internal mammary metastasis st