Positive axillary sentinel lymph node: Is axillary dissection always necessary?

Summary: There is considerable interest in foregoing axillary dissection (AD) when the sentinel node (SN) is positive in early breast cancer, particularly when axillary involvement is minimal (micrometastases or isolated tumor cells). In fact, clinical practice has run ahead of the evidence, since recent population-based data indicate that AD is 'underused' in breast cancer patients when the SN is positive. Several trials are addressing the problem (IBCSG 23-01, ASCOG Z0011, EORTC AMAROS). Only Z0011 has published interim results, finding, after a median follow-up of 6.3 years, no differences in locoregional recurrence or regional recurrence between patients, with a positive SN, who received AD vs. no further axillary treatment. Our own retrospective study evaluated patients with micrometastases or isolated tumor cells in the SN who received no further axillary treatment. We found high five-year survival and low cumulative incidence of axillary recurrence, supporting the findings of Z0011 and justifying the increasingly common practice of foregoing AD in women with minimal SN involvement. It is important to sound a note of caution however: If axillary dissection is not always necessary in women with a positive axilla, it seems important to be able to reliably identify the patients at high risk of developing overt axillary disease who should receive elective AD. Ancillary analyses of the IBCSG 23-01 and AMAROS trials, still in follow-up, may be able to do this.