41 – Therapeutic Value of Axillary Node Dissection and Selective Management of the Axilla in Small Breast Cancers

Abstract Controversy has long existed regarding the biological implications and surgical treatment of regional lymph node metastasis in invasive breast cancer. Several factors have resulted in a renewed evaluation of axillary node dissection. First is the continuing biological controversy that axillary lymph node metastases are “indicators but not governors” of outcome in breast cancer. Indeed in all human cancers with few exceptions, this biological concept has been proved repeatedly, and in most studies addressing this issue, lymph node metastases have proved to be indicators only. Another factor that has led to resurgence of interest in the role of axillary node dissection is the downward trend in tumor size secondary to mammographic screening and the resulting decrease in proportion of patients with lymph node metastasis. Use of primary tumor characteristics and genomic patterns to aid in decisions to administer systemic chemotherapy, the failure of high-dose therapy with bone marrow support, and the increasing indications for systemic adjuvant therapy in most cases have also challenged the need for axillary node dissection. Finally, with the advent of sentinel lymph node biopsy and its widespread application, the need for complete axillary evaluation has been questioned. This chapter summarizes the role of the lymphatic system in breast cancer and factors that have led to the decreased need for surgical axillary evaluation. Alternatives to axillary lymph node dissection, including axillary observation only in patients with small tumors, treatment of the axilla with tangential whole breast radiotherapy fields or axillary radiotherapy, lymph node evaluation by four- and five-node sampling, sentinel node biopsy, and the use of ultrasound to stage the axilla are also discussed. The continuing controversy surrounding the potential value of axillary dissection in breast cancer patients is explored.