[A new perspective on axillary dissection in situations of metastatic sentinel node]

Breast cancer is the most common malignant disease in women and represents a worldwide problem. Up-to-date diagnostics methods, mammography screening and complex treatments have resulted in a substantial reduction of mortality rates. However, the incidence of the disease keeps growing constantly, although in a moderate way. The struggle against this disease has several levels, such as prevention, primary tumour therapy as well as the management of recurrent or generalized disease. Therefore, it is very significant to evaluate the prognosis on the basis of biological characteristics of the tumour and to determine the right individual therapy in each patient.

Our aim was to determine a group of patients with malignant breast disease based on biological characteristics of the tumour who can be treated without axillary exenteration even with a metastasis in the sentinel lymph node, thereby reducing the morbidity associated with this surgery, without worsening the prognosis.

The research project lasted from June 2012 to June 2015. It was a prospective randomized study where the main investigated group consisted of women with primarily surgically treated mammary cancer undergoing sentinel lymph node biopsy (SNB) during their surgery. These patients were divided into three groups: group 1 - positive SNB without axillary exenteration (axillary dissection - AD); group 2 - positive SNB with AD; and group 3 - negative SNB. Group 4 consisted of patients with primarily performed AD. We investigated statistically significant prognostic factors of metastatic lymph nodes and early disease progression. The results were statistically processed and differences between individual groups were evaluated, determining prognostically usable biological characteristics of the tumour in connection with metastases in lymph nodes and progression-free survival.

The study included 214 patients with breast cancer. No metastases of axillary lymph nodes were found in 136 patients (64%); on the other hand, 78 patients (36%) had positive axillary lymph nodes and included: 28 (13%) patients with a micrometastasis in the sentinel lymph node; 38 (17%) patients with 13 positive lymph nodes; 8 (4%) patients with 49 positive lymph nodes; and 4 (2%) patients had more than 10 metastatic lymph nodes. A statistically significant difference with respect to metastatic lymph node involvement was found for the tumour size, expression of oestrogen receptors, proliferative activity and grading.

The following prognostic factors of metastatic lymph nodes and early disease progression were shown to be statistically significant: tumour size over 2 cm, negative expression of oestrogen receptors, tumours with moderate and high proliferative activity, and tumour grades G2 and G3. In the course of the three years of this study, no regional recurrence was found in axillary lymph nodes in any patient, and therefore, it clearly follows that the completion of axillary exenteration can be omitted in the case of tumour sizes below 2 cm, present expression of oestrogen receptors, low proliferative activity and grade 1 even if one or two positive sentinel lymph nodes are present, provided that adjuvant radiation therapy can be used. Also, axillary exenteration is not needed if a micrometastasis or isolated tumour cells are found in the sentinel lymph node.Key words: breast cancer - sentinel lymph node biopsy - axillary exenteration - prognostic factors.