Hypothesis: The incidence of nodal positivity in patients with early breast cancer is low, and axillary lymph node dissection may not be justified in all such patients. Design: Retrospective case series. Setting: Tertiary institution. Patients: All patients with T1a and T1b breast cancer who had both primary breast surgery and axillary lymph node dissection at Mayo Clinic in Jacksonville, Fla, from January 1, 1992, through February 28, 1998. Interventions: None. Main Outcome Measures: Tumor size and biological grade, estrogen and progesterone receptor status, number of nodes harvested, and number of nodes positive for disease. Results: Of 163 patients studied, 39 had T1a and 124 had T1b tumors. Node positivity was 0% for T1a and 11.3% for T1b tumors (P=.03). Lymph node involvement and estrogen receptor status were not related (P=.29). However, the risk of lymph node positivity for progesterone receptor-negative (P=.01) and estrogen receptor-negative/progesterone receptor-negative tumors was significantly higher than for progesterone and estrogen/progesterone receptor-positive tumors (P=.04). Furthermore, the risk of lymph node positivity was significantly higher as tumor size increased (P=.002). Finally, higher tumor grade conferred a higher risk of lymph node involvement (P=.02). Conclusions: T1a tumors have minimal risk of nodal positivity and may not require subsequent axillary lymph node dissection in the future. T1b tumors should be managed with routine analysis of axillary lymph node status. Whether sentinel node mapping can change this standard awaits further study.
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