Sentinel node biopsy (SNB) is used in the treatment of early stage breast cancer. This procedure is usually performed concomitant with breast conserving surgery or mastectomy.
There is a primary lymph node (sentinel node) which drains the lymph from a certain area.This sentinel node reflects the status of the remaining lymph nodes because the sentinel node is the first node where malignant cells from the primary tumor will locate. If the sentinel node does not contain tumor cells, the other lymph nodes in the axilla will, with a high probability, be free of metastases, and axillary dissection is unnecessary*.
Two methods are used for identifying sentinel nodes: radioactivity and staining. The radioactive isotope, 99m Tc-labeled colloidal human albumin, is injected some hours, or possibly one day, preoperatively. Methylene blue is injected immediately preoperatively. Lymphoscintigraphy is done after injection of radioactive isotope.
By this procedure, blue and/or radioactive lymph nodes are excised, and sent for histological examination or as frozen sections. Sentinel lymph nodes should have activity over 5 and preferably > 10x background activity.
- Invasive carcinoma stage T1 -T3 without evidence of lymph node metastasis.
- DCIS van Nuys grade 3 histologic where mastectomy will be performed. An axillary dissection should not be performed in this situation if the sentinel node is not found.
- If breast conserving surgery for DCIS is to be performed, SNB is not indicated. However, if the final diagnosis is invasive carcinoma, the SNB can be done afterwards.
- Avoid unnecessary axillary dissection
- Avoid destruction of lymph drainage of the arm
* Kim T et al. Lymphatic mapping and sentinel node biopsy in early stage breast carcinoma. Cancer 2006; 4-16