Abstract CS01-2: The role of radiation in the treatment of the axilla in the setting of neoadjuvant chemotherapy

Abstract

Abstract There is considerable controversy regarding the appropriate surgical procedure and its timing for evaluating the status of the axillary nodes in the neoadjuvant setting. Sentinel lymph node (SLN) surgery following initial chemotherapy avoids an axillary dissection and its associated morbidity in clinical N0 patients who have pathologic negative SLN. SLN identification and false negative rates (FNR) have been acceptable in these women and axillary recurrence rates without radiation directed to the axilla are £1%. For clinical N1 disease, 2 recent studies (SENTINA, ACOSOG 1071) reported SLN identification rates of 80% and 91%, FNR of 12.8 and 14% and ypN0 rates of 52% and 40% respectively. The SLN was the only positive node(s) in 58% and 40% of the ypN1 patients. Several studies have evaluated the role of regional node (RN) irradiation in clinical N1 patients who are ypN0 following neoadjuvant chemotherapy and have found no improvement in local-regional disease free survival. RN failure rates are low as reported by the NSABP B18 and 27 trials in the absence of post mastectomy radiation or with breast only radiation. The question of RN radiation is being addressed by an NRG (NSABP-RTOG) randomized trial. For women with clinical N1 disease who remain ypN1, axillary radiation may substitute for axillary dissection. Axillary radiation has been shown in randomized trials to be equivalent to axillary dissection in the adjuvant setting for clinical N0 women (NSABP B04) including those with positive SLN (Dutch Mirror, IBCSG 23-01, AMAROS). The Alliance trial will address this question. The potential advantage of neoadjuvant chemotherapy is the ability to adjust surgical and radiation treatment based on pathologic response and thereby minimize the morbidity of combined therapy. Various clinical scenarios will be presented with treatment options. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr CS01-2.