Abstract P3-01-10: Can we predict the risk for non-sentinel node metastases? Results from the Swedish breast cancer registry on 23053 patients
Authors: VikhePatil E , Arnesson L-G , Fohlin H 
Published: February 2018

Abstract
Introduction
Performing axillary clearance after node positive sentinel node biopsy (SNB) has been challenged. This register study aimed to predict the risk for non sentinel node metastases (non-SN) after axillary clearance in Swedish breast cancer patients. The Swedish Breast Cancer Registry has been in use since 2008 with &gt;99% compliance. National guidelines recommended axillary clearance for macro-and micromets in SN but not for isolated tumor cells (ITC). Breast cancer screening is performed nationwide.
Methods
Registerdata for 33 314 patients, 2008 until May 2012, was evaluated. SN was performed in 23 053 patients corresponding to 69% of all patients, a stable figure since 2008.This cohort of 23053 patients is further investigated. The median age was 62 years. Breast conserving surgery (BCS) was performed in 61,5%. SN detection mode was radiocolloid and blue dye injection and often (41%) lymphoscintigraphy. Mean tumor size after BCS -16mm and in mastectomy (ME) -23 mm. BCS and ME show positive SN in 19% and 31% respectively (sign.&lt;0.001). Number of excised nodes after axillary clearance was 13 (range 1-50). The dataset is not fully complete in all variables.
Results
Median harvested SNs was 2 (range 1-8). 5694 SN+ cases were found, distributed as14,9% macromets, 6,4% micromets and 2,0% ITC on the whole SN cohort. Screening detected cancers had metastatic SN in18 % while clinical cases showed positivity in 28% (sign.).
Altogether non-SN mets were found for 31% of SN positive patients. The risk of non-SN mets is: if 1 macromet in SN, 35% had further involved nodes. If 2 macromets in SNs, 49 % had non-SN mets and if ≥3 positive SNs the figure was 66% positive non-SN nodes (sign.p&lt;0.01). Evaluating 1299 SN micrometastatic cases gave these figures of freedom of non-SN mets: 1 micromet. node 86%, 2 micromets. 77% was free and ≥3 micromets show 61,5% non-involved mets. These figures are also significant. Data on lymphovascular invasion (LVI) was available for 18754 cases and showed a significant higher risk for non-SN mets in LVI-positive tumors 43% against 27%. Tumours &gt;20 mm and HER2 positive also show significant more non-SN mets.
Conclusion
The SN diagnostic technique works well in Sweden; 69% of patients had SN as the primary axillary procedure. SN+ was shown in 24,7%.The risk for non-SN mets is significant correlated to 2 or more involved SNs, positive LVI, tumour size &gt;20 mm and HER2+. Is this the group for axillary surgery? We will try to get a Swedish risk score for non-SN+. A new Swedish national randomized study now investigates the need for axillary clearance in a subset of SN+ patients.
Figures are collected from The Swedish Breast Cancer Registry-head K. Sandelin, Stockholm, Sweden.
Citation Format: VikhePatil E, Arnesson L-G, Fohlin H. Can we predict the risk for non-sentinel node metastases? Results from the Swedish breast cancer registry on 23053 patients [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-01-10.