The Sentinel Node with Isolated Breast Tumor Cells or Micrometastases. Benefits and Risks of Axillary Dissection

Sentinel lymph node (SLN) biopsy has become the standard procedure to identify metastases in axillary nodes in breast cancer. Even after careful SLN examination additional micrometastases and isolated tumor cells (ITCs) are sometimes found, resulting in a need for delayed axillary lymph node dissection (ALND). This study was undertaken to assess prognostic factors identifying additional axillary lymph node (ALN) metastases at delayed ALND.

To define the impact of late ALND regarding their outcome, 162 breast cancer patients with 169 operated breasts treated between 2010 and 2012 were evaluated, with follow-up through 2016. Data were collected on the patients, histology and biologic profile of the cancer, lymph node involvement, recurrence of breast cancer and adverse effects of ALND.

With thorough examination and immunohistochemical stainings twenty-nine of 168 SLN biopsies (28 patients, 17% of the patients) showed micrometastases or ITC, and a full ALND was performed at a later time. During these ALNDs 13 to 31 lymph nodes were removed. Additional ALN metastases were found in three (10%) patients. Two (7%) of the 28 patients with triple-negative cancer deceased of metastatic breast cancer. Three patients (11%) reported adverse effects of ALND requiring physiotherapy due to pain, stiffness, swelling or arm oedema. Tumor factors such as molecular subtype (p=0.002), tumor size (p=0.004), and proliferation index (Ki-67) (p=0.003) correlated with higher numbers of ALN metastases.

Since most patients with micrometastases found in the primary operation showed no additional positive lymph nodes, completion ALND may not be required in patients with micrometastases or ITCs in the SLN. In our study, the predictive factors for additional ALN metastases were tumur size, molecular subtype and proliferation index. It is conceivable that the features of the primary tumor, rather than the amount of cancer cells in the SLN, might serve to identify patients in whom ALDN can be avoided.