There are three levels of axillary lymph nodes (the nodes in the underarm or "axilla" area):
- Level I is the bottom level, below the lower edge of the pectoralis minor muscle.
- Level II is lying underneath the pectoralis minor muscle.
- Level III is above the pectoralis minor muscle.
A traditional axillary lymph node dissection usually removes nodes in levels I and II. For women with invasive breast cancer, this procedure accompanies a mastectomy. It may be done at the same time as, or after, a lumpectomy (through a separate incision).
Based on the doctor's physical exam and other indicators about the likelihood that cancer has spread to your lymph nodes, the surgeon will generally remove between five and thirty nodes during a traditional axillary dissection. The total number of lymph nodes "involved" (showing evidence of cancer) is more important than the extent of cancer in any one node.
Your doctor will let you know if any lymph nodes were involved (and if so, how many), as well as the extent of tumor involvement in each node.