Applying the American College of Surgeons Oncology Group Z0011 Trial; Can Histological Parameters Predict Axillary Nodal Understaging in Breast Carcinomas ?
Kate M O'Connor, Aoife J McCarthy, Fionnuala O'Connell, Tara Jane Browne, Michael W Bennett. Cork University Hospital, Cork City, Ireland
Background: The American College of Surgeons Oncology Group Z0011 trial demonstrated that T1-T2 breast carcinoma patients with one or two positive sentinel lymph nodes, treated with whole-breast irradiation and systemic chemotherapy who do not proceed to axillary dissection do not have inferior survival, compared to those who do have axillary dissection. The implication is that such patients no longer require axillary lymph node dissection (ALND). The aim of this study is to determine whether application of the Z0011 trial would understage a proportion of patients and potentially lead to their undertreatment. We further aimed to investigate whether primary tumour and sentinel nodal metastasis characteristics could aid identification of understaged tumours.
Design: 331 consecutive breast carcinoma cases were anlaysed of whom 68 patients with T1-T2 tumours underwent sentinel lymph node (SLN) biopsy and axillary clearance. Main tumour characteristics analysed included grade, size, lymphovascular invasion and hormone status. Nodal metastasis characteristics analysed included grade of metastasis, nuclear grade,mitotic count / 300 cells, Ki-67/10HPF and Ki-67 per 300 cells.
Results: 59 patients (87%) had 1 or 2 positive SLNs and 17 (29%) of these had further positive nodes on axillary dissection. Of these 17 patients 7 (12%) were upstaged. Of these patients the average tumour size was larger in those who were upstaged by their axillary dissection compared to those who remained at the same stage (3.4cm vs. 2.4cm). Tumour grade,lymphovascular invasion, receptor status, SLN metastasis grade, Ki-67/10HPF and per 300 cells on the SLN metastasis and mitotic count /300cells on the SLN metastasis were not associated with nodal upstaging at subsequent axillary dissection (p= > 0.05).
Conclusions: If the results of the Z0011 trial are applied as currently suggested a significant number of patients will be understaged by omission of axillary clearance (12%). Tumour size is larger in these understaged patients, suggesting further analysis of this parameter in predicting non sentinel lymph node metastasis in T1- T2 tumours with one or two positive sentinel lymph nodes is warranted.
Wednesday, March 21, 2012 9:30 AM
Poster Session V # 21, Wednesday Morning