K. Englander3, K. Elleson1, J. Gallagher3, N. Chintapally3, J. Whiting2, W. Sun1, C. Laronga1, M. Lee1 1Moffitt Cancer Center And Research Institute, Breast Oncology, Tampa, FL, USA 2Moffitt Cancer Center And Research Institute, Biostatistics And Bioinformatics, Tampa, FL, USA 3University Of South Florida College Of Medicine, Tampa, FL, USA
Introduction: Lymph node metastasis is an important prognostic factor in breast cancer. Our primary aim was to evaluate the relationship between tumor size, location, distance to the nipple, hormone receptor subtype and lymph node positivity in early stage (T1) breast cancer patients.
Methods: This is a single institution retrospective chart review of stage I female breast cancer patients diagnosed with primary invasive breast cancer treated with upfront surgical resection from 1998-2019. Neoadjuvant, multicentric, bilateral, inflammatory, and in situ only cases were excluded. Tumor size in mm was a continuous variable. ANOVA test or Student T test was applied to test the association of continuous variables and nodal positivity, and Chi-square test (or Fisher exact test if applicable) was applied to test the association of categorical variables and nodal positivity.
Results: We identified 464 stage T1 patients treated with upfront surgical resection. 1.3% were T1mi, 12.9% T1a, 21.8% T1b, 64% T1c. 163/464 (35.1%) had nodal metastasis and there was a significant relationship between larger tumor size and nodal metastasis (16.4 vs. 11.4; p<.001). A larger mean tumor size was also associated with recurrence (23.9 vs 12.5; p<.001). The mean tumor distance to the nipple in node positive patients was 44.4 mm versus 62.7 mm in patients with negative nodes (p<.001), but there was no relationship between tumor distance to the nipple and node burden (p=.332). 38.3% of tumors with nodal metastasis were in the upper outer quadrant (UOQ) of the breast (p=.009). There was a significant relationship between increasing T-stage and lymphovascular invasion (p=.038) as well as ALND (p=.001). 22/47 (46.8%) HER2/neu+ patients, 8/41 (19.5%) ER-/PR-/HER2- patients, and 144/403 (35.7%) ER+ patients had nodal metastasis.
Conclusion: Larger tumor size, shorter tumor distance to the nipple, and UOQ location were associated with nodal positivity. HER2/neu+ molecular aberration had the highest rate of metastasis among T1 patients. Further study is warranted to determine predictors of metastasis in stage T1 disease.
