Impact and Outcomes of Routine Microstaging of Sentinel Lymph Nodes in Breast Cancer: Significance of the pN0(i+) and pN1mi Categories

Annals of Surgical Oncology (Impact Factor: 3.93). 12/2008; 16(1):113-120. DOI: 10.1245/s10434-008-0121-x


BackgroundIn 2003, the American Joint Committee on Cancer (AJCC) initiated the 6th edition staging criteria, including pN0(i+) and pN1mi
categories for breast cancer. However, the clinical significance of these categories is debated in the literature.

MethodsA prospective registry was used to identify patients staged with sentinel lymph node (SLN) biopsy. SLN evaluation included
routine serial sectioning and immunohistochemical stains. SLN biopsies performed before January 2003 were restaged according
to the AJCC’s 6th edition criteria.

ResultsOf 954 SLN biopsies identified, on review, 491 N0i-, 86 N0i+, 73 N1mi, 146 N1a, 29 N2a, and 11 N3a patients were available
for analysis with a median follow-up of 45.4 months. Significant prognostic and therapeutic differences existed between the
groups. Differences in overall survival (OS) and recurrence-free survival (RFS) were only noted when the size of the metastases
reached the N1a level. There were no statistically significant differences in OS or RFS between N0(i−) and N0(i+) or N1mi
disease. Cases that were N0(i+) or N1mi were more likely to have other poor prognostic factors and to receive more aggressive

ConclusionSLN biopsy allows a more sensitive evaluation of lymph nodes for metastatic cells. This has led to the increased identification
of very small axillary metastases. While the new microstaging categories are not yet clearly associated with a significantly
decreased OS or DFS in this series, they are associated with other poor prognostic factors and more local/regional and systemic
therapy. Further analysis of the microstaging categories is needed.

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