Abstract P1-01-26: The feasibility of SNIPE trial; sentinel lymph node biopsy vs. no-SLNB In patients with early breast cancer
Authors: Nadeem RM 
Published: August 2014

Abstract
Background: The results of ZOO11 have shaken our longstanding approach for the axillary management of small invasive breast cancers where the incidence and burden of axillary metastasis would be much less than that of ZOO11 population. The traditional approach of sentinel lymph node biopsy (SLNB) for ‘‘all invasive cancers’’ is challenged due to the diminishing role of axillary lymph nodes (ALNs) status in guiding adjuvant systemic therapy. Certainly this raises the question of whether SLNB can be avoided in a select group of patients without compromising clinical outcomes? The aim was to identify a group of patients with a very low burden of axillary disease where SLNB is no longer required. The feasibility of the proposed SNIPE trial; Sentinel lymph node biopsy vs. No-SLNB In Patients with Early breast cancer was discussed and compared with SOUND trial, Sentinel node vs. Observation after axillary UltrasouND.
Method: Patients with breast cancers ≤ 2 cm in size, clinically node negative who underwent breast conserving surgery and SLNB were identified. Patients were divided into different groups according to clinicopathological variables. The incidence of ALNs metastasis, further non-SLNs metastasis and ≥ 4 total number of tumour positive ALNs were determined.
Results:194 patients met the inclusion criteria. The mean patient age was 58.5 y;75% were ≥ 50 y. The incidence of tumour positive ALNs is &lt; 5% in T1b, G1-2 tumours where SLNB could be omitted without compromising the surgical outcomes. The burden of axillary nodal disease is shown below:
Incidence and burden of axillary metastasis in different groups.GroupsT1 tumours(SOUND trial)T1, G1-2T1b tumoursT1b, G1-2(SNIPE trial)T1 and G1≤ 15mm G1-2≤ 15mm G1Total patients with T1 tumours and clinically negative axilla with no multifocality of tumour = 194Number of patients1941514943579243Incidence of ALNs mets30/194(15.5%)20/151(13.3%)6/49(12.4%)4/43(9.3%)8/57(14%)15/92(16.3%)7/43(16.3%)Incidence of ALNs mets excluding micromets13.4%11.9%6.1%4.6%10.5%13%11.6%OSM (Overall size of metastasis) mean, median, range.4.1,3(0.3-19)3.7,3(0.3-9)3.5,1.9(0.3-9)3.5,3(0.3-9)3.7,3(0.3-9)3.7,3(0.3-9)3.7,3(0.3-9)Incidence of non-SLNs metastasis9/30(30%)7/20(35%)1/6(16.7%)0%2/8(25%)3/15(20%)2/7(28.6%)Incidence of ≥ 4 total number of tumour positive ALNs5/194(2.5%)4/151(2.6%)1/49(2%)0%1/57(1.7%)1/92(1.1%)1/43(2.3%)
Conclusion: It is possible to identify a group of patients where burden of axillary disease is acceptably low enough that SLNB can be avoided. Feasibility of a non-inferiority, multi-centres Randomized Controlled Trial in a select group of patients with or without SLNB has been explored to compare the distant disease free, disease free and overall survival and axillary relapse rate. Patients with 2 ≤ tumour positive SLNs would not have axillary node dissection inline with the recommendations of ZOO 11 trial. Overall, 1600 patients would be required to show that the group without SLNB is no more inferior in the outcomes to that with SLNB. Inclusion criteria and management of tumor positive SLNs in this proposed trial is open to discussion and should be debated intensively before starting such an important trial which may also improve accrual for this trial.
Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-01-26.