Re: Influence of the New AJCC Breast Cancer Staging System on Sentinel Lymph Node Positivity and False-Negative Rates

Extract

The new American Joint Committee on Cancer (AJCC) staging system for breast cancer correctly recognizes that small clusters of malignant cells do not confer the same adverse prognostic impact as larger metastatic deposits ( 1 ). The AJCC’s decision to place patients with small clusters of malignant cells in the N0 category rather than the N1 category is rational. Also rational is their use of special substages based on findings from immunohistochemical or molecular techniques to distinguish patients that have otherwise undetectable metastatic deposits from patients with no evidence of disease in regional lymph nodes.

McCready et al. ( 2 ) misapply these staging guidelines by examining the impact of their use on the decision about the need for axillary dissection in patients undergoing sentinel lymphadenectomy. The reasonably low false-negative rates for sentinel lymphadenectomy have been achieved because malignant cells are more extensively evaluated in this procedure than in the standard analysis of axillary lymph nodes ( 3 ). Reducing the threshold for performing full axillary dissection would be expected to adversely affect the false-negative rate. There is nothing in the AJCC guidelines to suggest that fewer axillary dissections should be performed ( 4 ). Rather, the guidelines merely state that if the only evidence of lymph node metastases consists of clusters of tumor cells less than 0.2 mm in maximum diameter, the patient should be classified as pN0. Thus, if axillary dissection is performed and lymph node metastases greater than 0.2 mm are detected, the patient should be classified as pN1. Otherwise, the patient should be staged as pN0.