Prognostic significance of the number of axillary lymph nodes removed in patients with node-negative breast cancer.

PURPOSE: The objective of the study was to evaluate the association between the number of lymph nodes removed at axillary dissection and recurrence and survival for patients with node-negative invasive breast cancer. PATIENTS AND METHODS: Subjects were 2,278 women with pathologically node-negative invasive breast cancer, diagnosed from 1989 to 1993 in British Columbia, Canada. Women aged > or = 90 years, with pure in-situ, bilateral invasive breast cancer or T4, N1, N2, or M1 stage, or who had axillary radiation were excluded. Two groups were defined for analysis: node-negative with no systemic therapy (n = 1,468) and node-negative with systemic therapy (n = 810). Median follow-up was 7.5 years. Prognostic variables assessed were age at diagnosis, tumor size, tumor grade, invasion of lymphatics, veins, or nerves, estrogen receptor status, and number of nodes removed.
RESULTS: For patients not receiving systemic therapy, regional relapse was significantly increased with smaller numbers of nodes removed (P =.03). There was a trend toward shorter overall survival with fewer nodes removed (P =.06). Node-negative patients who received systemic therapy did not have a higher regional relapse rate or shorter overall survival when fewer nodes were recovered.
CONCLUSION: Recovery of a small number of negative lymph nodes at axillary dissection likely understages patients and leads to undertreatment, resulting in an increased regional relapse rate and poorer survival. The use of systemic therapy may overcome this effect. The number of nodes removed, in conjunction with other prognostic factors, may be useful in selecting node-negative patients for systemic therapy.