ORIGINAL ARTICLE

Non-sentinel lymph node involvement in patients with breast cancer and sentinel node micrometastasis; too early to abandon axillary clearance

M A den Bakker¹, A van Weeszenberg¹, A Y de Kanter², F H Beverdam⁵, C Pritchard⁴, Th H van der Kwast¹ and M Menke-Pluymers³

¹ Department of Pathology, Erasmus Medical Centre Rotterdam, Daniel den Hoed Location, Groene Hilledijk 301, PO Box 5201, 3008 AE, Rotterdam, Netherlands
² Department of Radiotherapy, Erasmus Medical Centre Rotterdam
³ Department of Surgery, Erasmus Medical Centre Rotterdam
⁴ Department of Research and Development Support Unit, Royal Cornwall Hospitals Trust, Treliske Hospital, Truro, Cornwall, TR1 3LJ, UK
⁵ Department of Surgery, Medisch Centrum Rijnmond Zuid, Location Zuider, 3075 EA Rotterdam, Netherlands

Correspondence to:
Correspondence to:
Dr M A den Bakker, Department of Pathology, Erasmus Medical Centre Rotterdam, Daniel den Hoed Location, Groene Hilledijk 301, PO Box 5201, 3008 AE, Rotterdam, Netherlands;
michael{at}dbakker.demon.nl

Aims: It has been suggested that patients with T1–2 breast tumours and sentinel node (SLN) micrometastases, defined as foci of tumour cells smaller than 2 mm, may be spared completion axillary lymph node dissection because of the low incidence of further metastatic disease. To gain insight into the extent of non-sentinel lymph node (n-SLN) involvement, SLNs and complementary axillary clearance specimens in patients with SLN micrometastases were examined.

Methods: A set of 32 patients with SLN micrometastases was selected on the basis of pathology reports and review of SLNs. Five hundred and thirteen n-SLNs from the axillary clearance specimens were serially sectioned and analysed by means of immunohistochemistry for metastatic disease. Lymph node metastases were grouped as macrometastases (> 2 mm), and micrometastases (< 2 mm), and further subdivided as isolated tumour cells (ITCs) or clusters.

Results: In 11 of 32 patients, one or more n-SLN was involved. Grade 3 tumours and tumours > 2 cm (T2–3 v T1) were significantly associated with n-SLN micrometastases as clusters (grade: odds ratio (OR), 8.3; 95% confidence interval (CI), 1.4 to 50.0; size: T2–3 tumours v T1: OR, 15; 95% CI, 2.18 to 103.0). However, no subgroup of tumours with regard to size and grade was identified that did not have n-SLN metastases.

Conclusions: In patients with breast cancer and SLN micrometastases, n-SLN involvement is relatively common. The incidence of metastatic clusters in n-SLN is greatly increased in patients with T2–3 tumours and grade 3 tumours. Therefore, axillary lymph node dissection is especially warranted in these patients. However, because n-SLN metastases also occur in T1 and low grade tumours, even these should be subjected to routine axillary dissection to achieve local control.

Keywords: sentinel node; micrometastasis; breast cancer; pathological staging

Abbreviations: CI, confidence interval; H&E, haematoxylin and eosin; IHC, immunohistochemistry; ITC, isolated tumour cell; LN, lymph node; n-SLN, non-sentinel lymph node; OR, odds ratio; SLN, sentinel lymph node

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