The Prognostic Effect of the Number of Histologically Examined Axillary Lymph Nodes in Breast Cancer: Stage Migration or Age Association?
The number of pathologically examined axillary nodes has been associated with breast cancer survival, and examination of ≥10 nodes has been advocated for reliable axillary staging. The considerable variation observed in axillary staging prompted this population-based study, which evaluated the prognostic effect of a variable number of pathologically examined nodes.
In total, 5314 consecutive breast cancer patients who underwent mastectomy or breast-conserving surgery and axillary dissection between 1994 and 1999 were included. The prognostic effect of the examined number of nodes was assessed with crude and relative survival analysis.
A median number of 12 (range, 1–43) nodes were histologically examined, and 59% of the patients had no nodal tumor involvement. The number of examined nodes decreased with age (P < .001) and increased with tumor size (P < .001). Stratified for the number of tumor-positive nodes, overall survival seemed to be worse for patients with <10 compared with patients with ≥10 examined nodes (P < .001), whereas the relative survival did not differ. After adjusting for age, tumor size, number of positive nodes, and detection by screening in a multivariate analysis, the number of examined nodes was not associated with relative survival.
This study shows that the association between the number of pathologically examined axillary nodes and overall survival in node-negative and node-positive patients results from stage migration. The absence of an association between the number of examined nodes and relative survival further indicates that the association between the number of examined nodes and crude survival is confounded by age.
KeywordsBreast cancer Axillary staging Crude survival Relative survival Prognosis
- 1.National Comprehensive Cancer Network: update of the NCCN guidelines for treatment of breast cancer. Oncology 1997;11:199–222Google Scholar
- 12.Rosen PP, Lesser ML, Kinne DW, Beattie EJ. Discontinuous or “skip” metastases in breast carcinoma: analysis of 1228 axillary dissections. Ann Surg 1983;4:655–62Google Scholar
- 24.Hermanek P, Sobin LH (eds). International Union Against Cancer (UICC): TNM Classification of Malignant Tumors. 4th ed, 2nd rev. Berlin: Springer-Verlag, 1992Google Scholar
- 25.Sobin LH, Wittekind C (eds). International Union Against Cancer (UICC): TNM Classification of Malignant Tumors. 5th ed. New York: Wiley-Liss, 1997Google Scholar
- 26.Statistics Netherlands/Centraal Bureau voor de Statistiek. Available at: http://www.statline.cbs.nl/StatWeb [accessed February 2, 2006]
- 27.Ederer F, Heise H. Instructions to IBM 650 Programmers in Processing Survival Computations. Methodological Note No. 10, End Results Evaluation Section. Bethesda, MD: National Cancer Institute, 1959Google Scholar
- 29.McCullagh P, Nelder JA. Generalized Linear Models. 2nd ed. London: Chapman & Hall, 1989Google Scholar
- 32.Early Breast Cancer Trialists’ Collaborative Group. Tamoxifen for early breast cancer: an overview of the randomised trials. Lancet 1998;351:1451–67Google Scholar
- 33.Early Breast Cancer Trialists’ Collaborative Group. Polychemotherapy for early breast cancer: an overview of the randomised trials. Lancet 1998;352:930–45Google Scholar