Can removal of the axillary lymph nodes be avoided if there is minimal involvement of the sentinel lymph nodes in breast cancer?

This study tested the effect of complete axillary lymph node removal, on survival without recurrence of the cancer (called disease free survival or DFS) in patients with breast cancer. 

Lymph nodes are small organs which are part of the immune system. They filter fluid called lymph. Lymph can be thought of as the sewer system of the body. It drains fluid from tissues and from in between the cells. When cancer is detected in the body, the first lymph node draining the area of the cancer is checked to see if the cancer has spread to it. This is called the sentinel lymph node. In the case of breast cancer, these lymph nodes are found in the axillary (arm pit) region. A biopsy (microscopic examination of a tissue sample taken with a needle or by small surgery) of the lymph nodes indicates if the patient's cancer has spread. Usually, if cancer cells are found in the sentinel node, all axillary lymph nodes are removed. This surgery is referred to as complete axillary lymph node dissection. It has been suggested though, that in patients showing only a limited involvement of the sentinel node, this complete dissection might be considered as overtreatment.

This phase III trial included 931 patients with an early stage breast cancer. All patients showed minimal involvement of the sentinel lymph node when a biopsy was performed. 464 patients were randomly chosen to receive a complete axillary lymph node dissection. The remaining 467 patients had only the sentinel nodes removed, but did not receive a complete axillary node dissection. Patients were followed for five years to check whether complete axillary node dissection affected prognosis.

Results showed that patients who did not undergo complete axillary node dissection had just as good an outcome as those who did. 5 years after surgery, DFS was 84.4% for patients in the group that underwent complete axillary node dissection, compared to 87.8% in the group that did not receive a complete dissection. In addition, 7 patients in the complete axillary node dissection group reported side effects such as damage to the nerves in the region related to the surgery itself. 

In this study, the complete removal of the axillary lymph nodes could be avoided in patients with minimal sentinel lymph node involvement.

The results of this study are similar to previously published trials on the subject. This gives these results greater credibility. However, it should be noted that only patients with very limited (<2mm) involvement of the lymph nodes were included, and these results are relevant only to these patients.

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