The Predictive Value of Micrometastasis in Nonsentinel Lymph Nodes

The rate of micrometastatic disease (MMD) to nonsentinel lymph nodes (NSLNs) has been shown to vary considerably in the literature. We identified patients with breast cancer with MMD (N1mi) and measured the incidence of NSLN involvement. We then compared these patients with those who had no metastasis to the SLN (N0) and those who had macrometastasis to the SLN (N2) in an attempt to better understand the behavior of patients with N1mi positivity. A retrospective analysis was conducted on 574 patients with invasive breast cancer between January 2000 and December 2007. Patients were stratified into three groups: no metastasis (N0), MMD (N1mi), and macrometastasis (N2). Chi square analysis and logistic regression models using SPSS software were applied to determine significance between groups. MMD rate was 7.7 per cent (44 of 574). Of this subset of patients, 33 underwent completion axillary dissection, and only two were found to have NSLN-positive disease. Statistical significance was achieved for NSLN positivity when comparing all three nodal groups against one another (χ22,572 = 337.084, P = 0.000). Logistic regression showed multifocality and lymphovascular invasion to be significant predictors of NSLN metastasis. NSLN positivity in patients with MMD acts similarly to node-positive disease and therefore cannot completely exclude axillary dissection from therapeutic algorithm.

Prognostic impact of isolated tumor cells in breast cancer axillary nodes: single tumor cell(s) versus tumor cell cluster(s) and microanatomic location

In breast cancer, it has been shown that pN0(i+) and pN1mi have a comparable negative impact on disease-free survival, compared with pN0. However, pN0(i+) is considered to be a heterogeneous group. We determined the effect of metastatic size and microanatomic location within the pN0(i+) group on breast cancer recurrence. We included all Dutch breast cancer patients diagnosed in 1998-2005 with favorable primary tumor characteristics and a final nodal status of pN0(i+). For this analysis, only patients without adjuvant systemic therapy were eligible (n = 513). Presence of single tumor cells versus cell clusters, metastatic size and microanatomic location were recorded. Primary endpoint was disease-free survival. Analyses were adjusted for age at diagnosis, tumor size, tumor grade, axillary treatment and hormone receptor status. The 5-year disease-free survival of patients with single tumor cell(s) (n = 93) was 78.6% and with tumor cell cluster(s) (n = 404) 77.1%. The hazard ratio for disease events was 1.05 (95% CI 0.63-1.76) for cell cluster(s) compared with single cell(s). In a Cox regression model, doubling of metastatic tumor size corresponded to a hazard ratio of 1.21 (95% CI 1.02-1.43). The adjusted hazard ratio was 0.90 (95% CI 0.54-1.50) for parenchymal (n = 112) versus sinusoidal location (n = 395). Single tumor cells bear similar prognostic information as small tumor cell clusters, even though results do suggest that within the pN0(i+) group, increasing size of nodal involvement is associated with reduced survival. Microanatomic location does not seem to have prognostic relevance.

Axillary lymph node dissection in early-stage invasive breast cancer: is it still standard today?

Evaluation of axillary lymph node status by sentinel lymph node biopsy (SLNB) and complete axillary lymph node dissection (ALND) are an inherent part of breast cancer treatment. Increased understanding of tumor biology has changed the prognostic and therapeutic impact of lymph node status. Non-invasive imaging techniques like axillary ultrasound, FDG-PET, or MRI revealed moderate sensitivity and high specificity in evaluation of lymph node status. Therefore, they are not sufficient for lymph node staging. Otherwise, the impact of remaining micrometastases and even macrometastases for prognosis and treatment decisions is overestimated. Considering tumor biology, the distinction of axillary metastases in isolated tumor cells (ITC, pN0(i+)); micrometastases (pN1mi), and macrometastases (pN1a) is not comprehensible. Increasing data support the thesis that remaining axillary metastases neither increase the axillary recurrence rate nor decrease overall survival. It is doubtful that axillary tumor cells are capable to complete the complex multistep metastatic process. If applied, axillary metastases are sensitive to systemic treatment and are targeted by postoperative tangential breast irradiation. Therefore, the controversy about the clinical relevance of tumor cell clusters or micrometastases in SLN is a sophisticated but not contemporary discussion. Currently, there is no indication for axillary surgery in elderly patients with favorable tumors and clinically tumor-free lymph nodes. Nonetheless, a rational and evidence-based approach to the management of clinically and sonographically N0 patients with planned breast-conserving surgery and limited tumor size is needed now.