Is a completion axillary dissection indicated for micrometastases in the sentinel lymph node?

OBJECTIVE: The purpose of this study is to determine if a completion axillary dissection (CAD) is necessary when microscopic metastasis (<2 mm) is detected in the sentinel lymph node (SLN) of patients diagnosed with breast cancer.
METHODS: A retrospective chart review was performed on 227 consecutive breast cancer patients who underwent SLN mapping (SLNM) between June 1998 and March 2001. These patients underwent intraoperative lymphatic mapping with peritumoral injections of blue dye alone or in combination with technetium-labeled sulfur colloid. The SLN was assessed by touch preparation or frozen section at the time of surgery, and later, by hematoxylin and eosin stain. Patients in whom the SLN showed evidence of metastatic disease on frozen section underwent immediate CAD.
RESULTS: One patient was excluded because of inability to identify the SLN. Of the 226 patients in whom SLNM was successful, 67 (27%) had macrometastasis in the SLN, and a completion CAD was performed. Thirty-four of these 67 patients (51%) had additional disease in the axilla. A total of 15 patients (6.7%) was determined to have micrometastasis. In 11 patients, micrometastasis was identified and CAD was performed with no further evidence of disease. The 4 patients diagnosed with micrometastatic disease on permanent staining did not have further surgical intervention. The 15 patients identified with micrometastasis show no evidence of local recurrence to date, with a mean follow-up of 13.5 months (range 1 to 27).
CONCLUSIONS: This study suggests that CAD may not be necessary for the subset of breast cancer patients with micrometastasis detected upon SLNM. A larger randomized prospective study with long-term follow up is necessary to confirm these data.