In the case of primary surgery, in patients with sentinel node involvement, it has already been shown that omitting axillary lymph node dissection (ALND), often combining axillary radiotherapy (RT), does not worsen the prognosis and does significantly reduce the appearance of lymphedema. However, patients who have received neoadjuvant systemic treatment cannot benefit from this option, even though in the majority of those who have responded well to treatment, a residual disease in the armpit is low, but there are no studies yet published that supports the possibility of not performing lymphadenectomy. The primary endpoint is to evaluate wether axillary radiotherapy (ART) presents a lower risk of lymphedema with respect to lymphadenectomy (ALND) in patients with breast cancer who, after neoadjuvant systemic treatment (NST), present the sentinel node affected. Likewise, we will evaluate recurrences and overall survival in both groups. Finally, we will analyze the quality of life of these patients.