Role of total tumour load of sentinel lymph node on survival in early breast cancer patients.

ABSTRACT

BACKGROUND: Axillary staging (pN) is considered one of the most important prognostic factors in breast cancer patients. However, the Z0011 study data drastically reduced the number of surgical axillary dissections in a selected group of patients, limiting the prognostic information relating to axillary involvement to the sentinel lymph node (SLN). It is known that there is a relationship between SLN total tumour load (TTL) and axillary involvement. The objective of this study is to analyse the relationship between the TTL and outcomes in patients with early stage breast cancer. PATIENTS AND METHODS: clinicopathological and follow-up data were collected from 950 patients with breast cancer between 2009 and 2010 on whom SLN analysis was conducted by molecular methods (One Step Nucleic Acid Amplification, Sysmex, Kobe, Japan). RESULTS: TTL (defined as the total number of CK19 mRNA copies in all positive SLN) correlates with disease free survival (HR, 1.08; p = 0.000004), with local recurrence disease free survival (HR = 1.07; p = 0.0014) and overall survival (HR 1.08, p = 0.0032), clearly defining a low-risk group (TTL <2.5 × 104 CK19 mRNA copies/µL) versus a high-risk group (>2.5 × 104 CK 19 mRNA copies/µL). CONCLUSIONS: SLN TTL permits the differentiation between two patient groups in terms of DFS and OS, independently of axillary staging (pN), age and tumour characteristics (size, grade, lymphovascular invasion). This new data confirms the clinical value of low axillary involvement and could partially replace the information that staging of the entire axilla provides in patients on whom no axillary lymph node dissection is performed.