The sentinel lymph node of breast cancer and the radiation oncologist.

If the indications of sentinel lymph node biopsy and axillary lymph node dissection have been the subject of many trials, the indications of radiotherapy, in the absence of axillary lymph node dissection are a matter of debate. We reviewed the available literature on this topic and tried to draw some practical applications. In case of negative result of a sentinel lymph node biopsy, patients could be viewed as having pN0 disease and indications of adjuvant radiotherapy based on this paradigm. However, when the result of a sentinel lymph node biopsy was positive and no axillary lymph node dissection performed, indications of adjuvant radiotherapy are not so clear. For example, micrometastases could indicate a nodal irradiation as in the AMAROS trial, or not as in the IBCSG trial. Indications of postmastectomy radiotherapy are also not clearly defined in this setting. In the end, a clinical proposal was designed, emphasizing the unanswered questions.