Correspondence to: Carl D. Atkins, MD, South Shore HematologyOncology Associates, 242 Merrick Rd., Ste. 301, Rockville Centre, NY 11570-5254 (e-mail: c3atkins{at}optonline.net)
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 AJCCs 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.
It is obvious that excluding patients with isolated tumor cells from the pN1 category will reduce the proportion of patients staged as node positive. The pertinent question is how this affects treatment. Axillary dissection or radiotherapy probably improves survival in patients with axillary lymph node metastases (5), and the detection of metastases identifies patients who will benefit more from systemic therapy (6). However, because of advances in pathologic techniques, we can no longer dichotomize patients into the simple categories of lymph nodepositive and lymph nodenegative. We must use our knowledge and skills to help patients understand the pros and cons of the treatment choices they must make, adding lymph node metastases to the long list of biologic variables that must be analyzed as part of a continuum. The new AJCC staging system appropriately reflects this continuum, but it should not be used as a basis for changing protocols for axillary dissection after sentinel lymphadenectomy.
REFERENCES
1 Hansen NM, Grube BJ, Te W, Brebbab ML, Turner R, Giuliano AE. Clinical significance of axillary micrometastases in breast cancer: how small is too small? [abstract 91] Proc ASCO 2001;20:24a.
2 McCready DR, Yong WS, Ng AK, Miller N, Done S, Youngson B. Influence of the new AJCC breast cancer staging system on sentinel lymph node positivity and false-negative rates. J Natl Cancer Inst 2004;96:8735.
3 Veronesi U, Pagenelli G, Viale G, Galimberti V, Luini A, Zurrida S, et al. Sentinel lymph node biopsy and axillary dissection in breast cancer: results in a large series. J Natl Cancer Inst 1999;91:36873.
4 Greene FL, Page DL, Fleming ID, Fritrz AG, Balch CM, Haller DG, et al. AJCC cancer staging manual. 6th ed. New York (NY): Springer; 2002. p. 2623.
5 Atkins CD. Breast cancer survival advantage with radiotherapy. Lancet 2000;356:126970.[CrossRef]
6 Ravdin PM, Siminoff LA, Davis GJ, Mercer MB, Hewlett J, Gerson N, et al. Computer program to assist making decisions about adjuvant therapy for women with early breast cancer. J Clin Oncol 2001;19:98091.
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