Predictors of Axillary Lymph Node Involvement in Women with T3 Breast Cancers: Analysis of 1988-2003 SEER Data

Background: We investigated characteristics associated with axillary lymph node (LN) status in patients with T3 breast cancers and hypothesized that LN status is an independent predictor of survival. Methods: Characteristics associated with axillary LN metastasis among women with T3 breast cancers were identified from the 1988-2003 Surveillance, Epidemiology, and End Results (SEER) database. The primary outcome was breast cancer-specific mortality. Cox models were used to calculate adjusted hazard ratios (aHR) and 95% confidence intervals (CI). Results: A total of 12,778 patients with T3 breast cancers were analyzed (8201 LN+, 3695 LN-, 882 unknown). LN+ patients were more likely to be <50 y, married, and have ER+/PR+, grade 3 invasive ductal cancers (P<0.01 for each). Most patients underwent mastectomy (87.4%). Post-mastectomy radiation was more commonly used in LN+ patients (P<0.01). LN+ patients had higher breast cancer-specific mortality (36.2% versus 16.4%, P<0.01) and were more likely to die during the follow-up period (aHR = 2.87, 95% CI: 2.62-3.15) compared with LN- patients. Conclusions: Analysis of the SEER database indicated that several patient and tumor characteristics predict a higher likelihood of axillary LN involvement in patients with T3 breast cancers. LN status was an independent predictor of survival in women with T3 breast cancers.