4.4 Outpost Lymph Node Biopsy and Case Analysis
The concept of outpost lymph nodes（SLN）is based on the hypothesis that primary tumors can reach the first lymph nodes in a specific lymphatic drainage area through the lymphatic tube，called SLN.SLN in breast cancer patients is usually only one armpit lymph node，and sometimes the lymph nodes are outside the armpits.There are 4 methods to determine the SLN of breast cancer patients：1.dye method，2.radionuclide method，3.preoperative lymphatic imaging plus radionuclide method in surgery，4.dye and radionuclide combined method.Technically，SLN includes blue-dyed lymph nodes，lymph nodes directly pointed by blue-dyed lymphatic tubes，lymph nodes with radioactive hot spots，and any pathologically suspicious lymph nodes found in SLN biopsies（SLNB）.Hot spots are the points with the highest radiation count of armpits outside the injection point，as well as the lymph nodes with a maximum count of more than 10%.No blue-dyed lymph nodes or blue-dyed lymphatic tubes were found to point to the lymph nodes，and no radioactive hot spots were found in the armpit lymph node sweeper specimens as biopsy failures.
NSABP B-32 and a series of large-scale prospective clinical trials of breast cancer SLNB through long-term follow-up have all suggested that SLN-negative patients with local control and survival rates are equivalent to ALND.SLNB can replace ALND in early patients.Many surgeons and oncology centers have abandoned，the conventional ALND in T1-2NO and SLN-negative patients.(https://www.daowen.com)
However，medical units carrying out SLNB should be equipped with the relevant technical and equipment conditions as much as possible，and require multidisciplinary team collaboration in surgery，imaging，nuclear medicine，pathology，etc.More importantly，surgeons should complete a certain number of（e.g.40 cases）of research cases（ALND after SLNB），and only after the individual SLNB success rate of 90%，false negative rate of 10%are reached can they be routinely carried out SLNB.