Axillary dissection for breast carcinoma. The myth of skip metastasis.

The question of what constitutes an adequate axillary dissection for breast cancer remains open for debate. Central to this controversy is whether axillary nodal metastasis occurs in a stepwise fashion or spreads sporadically, creating skip metastases. The therapeutic aim of axillary dissection also must be considered. To resolve this controversy, a prospective study involving 129 patients who underwent complete axillary dissection for breast carcinoma was performed. The tissue from the axillary dissections was divided intraoperatively and sent to the pathologist as two specimens. The first specimen contained all nodes lateral to the pectoralis minor muscle (Level I), whereas the second contained all nodes beneath and medial to the pectoralis minor (Levels II and III). The tissue was analyzed to determine the frequency of skip metastasis. Only two patients, 1.6 per cent of the total group or 3.2 per cent of the positive node group, were found to have a positive node in Level II-III with no metastasis in Level I. A thorough dissection of Level I alone is sufficient to detect more than 98 per cent of all axillary lymph node metastases from breast cancer. Thus, proper staging of the disease can be obtained. When Level I contained positive nodes, the probability of metastatic disease to higher levels was significant (45%), indicating further treatment is necessary in incomplete axillary dissections.