Prognostic significance of axillary dissection in breast cancer patients with micrometastases or isolated tumor cells in sentinel nodes: a nationwide study.

We estimated the impact of axillary lymph node dissection (ALND) on the risk of axillary recurrence (AR) and overall survival (OS) in breast cancer patients with micrometastases or isolated tumor cells (ITC) in sentinel nodes. We used the Danish Breast Cancer Cooperative Group (DBCG) database to identify patients with micrometastases or ITC in sentinel nodes following surgery for primary breast cancer between 2002 and 2008. A Cox proportional hazard regression model was developed to assess the hazard ratios (HR) for AR and OS between patients with and without ALND. We identified 2074 patients, of which 240 did not undergo further axillary surgery. The 5-year cumulated incidence for AR was 1.58 %. No significant difference in AR was seen between patients with and without ALND. The age adjusted HR for AR if ALND was omitted was 1.79 (95 % CI 0.41-7.80, P = 0.44) in patients with micrometastases and 2.21 (95 % CI 0.54-8.95, P = 0.27), in patients with ITC after a median follow-up of 6 years and 3 months. There was no significant difference in overall survival between patients with and without ALND, when adjusting for age, co-morbidity, tumor size, histology type, malignancy grade, lymphovascular invasion, hormone receptor status, adjuvant systemic treatment and radiotherapy, with a HR for death if ALND was omitted of 1.21 (95 % CI 0.86-1.69, P = 0.27) in patients with micrometastases and 0.96 (95 % CI 0.57-1.62, P = 0.89) in patients with ITC after a medium follow-up on 8 and 5 years. In this nationwide study, we found a low risk of AR on 1.58 % and we did not find a significantly increased risk of AR if ALND was omitted in patients with micrometastases or ITC in sentinel nodes. Furthermore, no significant difference in overall survival was seen between patients with and without ALND when adjusting for adjuvant treatment.