Clinical evidence of breast cancer micrometastasis in the era of sentinel node biopsy.

Sentinel node biopsy for early-stage breast cancer has been established as an excellent surgical and staging procedure developed to enhance the detection of minimal lymph node involvement such as micrometastases. Multisection and the proper use of immunohistochemical staining have led to the increased detection of micrometastases, and this has given rise to new questions about the treatment to be employed concerning micrometastasis. That is whether complete axillary lymph node dissection (ALND) and adjuvant systemic therapy are really required for patients with micrometastasis because of the low prevalence of nonsentinel lymph node metastasis. Some currently published case studies report that selected patients with micrometastases without further ALND would not suffer from a high incidence of regional recurrence. However, the long-term prognostic risk of systemic recurrence and local failure associated with residual axillary disease in the sentinel lymph node-positive patient electing for no further axillary surgery has not been defined. Numerous studies have investigated the impact of occult metastases, which may be regarded as micrometastases or a small tumor deposit. Although data from randomized controlled trials are lacking, these studies suggest that the prognosis of breast cancer patients with micrometastases should not be considered the same as that in truly node-negative patients. Patients with micrometastases should have some adjuvant systemic therapy. Ongoing randomized trials will provide prospective answers to the question of the optimal treatment for micrometastasis.