Abstract
Background: The need for axillary lymph node dissection (ALND) when sentinel lymph nodes (SLN) contain micrometastasis is controversial. The purpose of this study was to determine if the size of tumor in the SLN corresponds with additional positive non-sentinel lymph nodes (non-SLN) in pT1 breast cancer. Methods: This retrospective review of 483 patients with pT1 breast cancer identified 96 patients with tumor positive SLN biopsies between June 1999 and February 2010. The size of SLN metastasis and the number of tumor positive non-SLN were recorded using AJCC criteria. Receiver operating characteristic analysis was used to discriminate the SLN size with the optimal sensitivity, specificity and likelihood ratios (LR) for additional positive non-SLN. Results: Among 96 patients with a tumor positive SLN, 41% (n = 39) had micrometastasis, and 59% (n = 57) had macrometastasis. A positive non-SLN was identified after ALND among 18% (n = 7 of 39) with micrometastasis compared with 39% (n = 22 of 57) with macrometastasis (p = 0.04). The size of the SLN metastasis and presence of additional tumor positive non-SLNs corresponds to a positive likelihood ratio of 1.1 for micrometastasis and 1.6 for macrometastasis (95%CI: 0.56 - 0.74). Conclusions: Increased size of tumor in SLN is associated with greater likelihood of non-SLN positivity and should be considered for more aggressive follow-up and therapy.
Highlights
Sentinel lymph node (SLN) biopsy is the standard method for assessment of nodal involvement in clinically negative early breast lesions whereby only sentinel lymph nodes (SLN) containing metastasis require subsequent axillary lymph node dissection (ALND) [1]
A positive SLN was identified in 96 cases (19.9%), consisting of 40.6% (39/96) micrometastasis and 59.4% (57/96) macrometastasis
An additional 8 cases of Isolated tumor cells (ITC) (7.7%) were observed; these SLN were not classified as a positive SLN biopsy and were included only in the Receiver operating characteristic (ROC) curve analysis as the lowest cut point
Summary
Sentinel lymph node (SLN) biopsy is the standard method for assessment of nodal involvement in clinically negative early breast lesions whereby only SLNs containing metastasis require subsequent axillary lymph node dissection (ALND) [1]. Official guidelines from the American Society of Clinical Oncology (ASCO) released in 2005 advise all patients with SLN micrometastasis to undergo completion ALND, data from the National Cancer Institute’s Surveillance Epidemiology and End Results database suggest that fewer than 60% of patients with SNMM undergo additional axillary nodal clearance [1,3]. This change in clinicians’ attitude towards small volume SLN metastasis is reflected in a 2009 ASCO survey where 98.5% of those surveyed regard SNMM as important— only 23% of surgeons, 23% of medical oncologists and 15% of radiation oncologists recommend ALND for micrometastasis [5]. Conclusions: Increased size of tumor in SLN is associated with greater likelihood of non-SLN positivity and should be considered for more aggressive follow-up and therapy
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