Background: Guidelines advise modified radical mastectomy following neoadjuvant systemic therapy for T4 breast cancer. We studied the influence of current systemic therapy and tumor subtype on pathologic stage and practice patterns to identify patients for whom less aggressive operative treatment might be considered.
Methods: We identified 98 clinical T4 M0 cases operated on at our institution from October 2008-July 2015. Patient, tumor, and treatment variables were analyzed.
Results: Clinical T4 substage was 7% T4a, 32% T4b, 3% T4c, and 58% T4d. Tumor biologic subtype was 41% ER+/HER2-, 36% HER2+, and 23% ER-/HER2-. A total of 86 patients (88%) had neoadjuvant systemic therapy; 87% of patients underwent total mastectomy, 9% skin-sparing mastectomy, and 4% breast conservation. Axillary dissection was performed in 74% of patients and sentinel node surgery with (14%) or without (11%) axillary dissection in the remainder; 41/98 (42%) were lymph node negative at operation. The pathologic complete response rate in the breast (31%) and axilla (39%, cN+ cases) correlated with biologic subtype (P < .0001). Overall 5-year, disease-free, and breast cancer-specific survival were 68% and 86%.
Conclusion: Alignment with guidelines was substantial for both breast and axillary operation. Favorable breast cancer-specific survival suggests current multidisciplinary treatment has improved outcomes. Careful assessment of pathology and treatment response may identify clinical T4 patients appropriate for breast or axillary conservation.
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