Observational Study on Surgical Techniques for Axillary Lymph Nodes in Breast Cancer

Breast cancer (mammary carcinoma) is a malignant disease of the mammary gland tissue characterized by the uncontrolled proliferation of mammary gland cells. In addition to the primary tumor itself, the cancer cells can also spread through the lymphatic system and, for example, invade nearby lymph nodes in the armpit. Treatment of the disease depends on numerous factors, such as the patient’s overall health, the stage of the disease, the tumor’s growth rate (Ki-67 index), the presence of detectable hormone receptors on the surface of the cancer cells (estrogen receptor-positive, progesterone receptor-positive), and the increased expression of the HER2 receptor on the cells (HER2-positive).

If the disease has not already spread throughout the body (metastases) at the time of diagnosis, initial treatment typically involves chemotherapy (neoadjuvant therapy) with the goal of shrinking or completely destroying the tumor in the breast and, if necessary, the lymph nodes. This is followed by surgery to remove any remaining tumor. In cases of axillary lymph node involvement, it used to be standard practice to remove all lymph nodes in the affected armpit, regardless of whether tumor cells were detectable in each of these lymph nodes. However, this approach can cause significant discomfort for the patient, such as impaired lymphatic drainage in the arm. For this reason, only those lymph nodes that are confirmed to contain tumor cells are now typically removed (selective lymph node dissection). The reason for this change in treatment is study results showing that, as a result of neoadjuvant therapy alone, 60% of patients no longer have positive lymph nodes. Consequently, the actual benefit of the more invasive “complete lymph node dissection” is increasingly being questioned. However, the specific situation where more than three lymph nodes were involved and these appear uninvolved (ycN+) following neoadjuvant therapy has not yet been well studied. It remains unclear whether it is sufficient to to remove only the lymph nodes that were involved at the time of diagnosis, or whether there is a high probability that involved lymph nodes are being overlooked—lymph nodes that are mistakenly classified as non-involved prior to removal, even though they are actually affected (“false negative”).

The aim of this observational study is to investigate the safety of targeted lymph node resection in patients with more than 3 involved lymph nodes. To this end, the study evaluates how many of the lymph nodes initially assessed as uninvolved—and thus left in place during targeted lymph node resection—ultimately showed tumor cells on histopathological examination after the subsequent removal of all lymph nodes, meaning they were incorrectly classified as normal. The study does not test any new medications or surgical techniques, nor does it involve any novel therapies.

Patients aged 18 and older with breast cancer and at least 3 affected lymph nodes are eligible to participate in this study. The positive lymph nodes must have been confirmed by biopsy. There must be a recommendation for neoadjuvant therapy followed by surgery to remove the lymph nodes.