Predictors of Pathological Complete Response in Women with Clinical Complete Response to Neoadjuvant Chemotherapy in Breast Carcinoma

OBJECTIVE: There is insufficient information on predictors of pathologic complete response (pCR) to neoadjuvant chemotherapy (NAC) in breast carcinoma that also presented clinical complete response (cCR) evaluated in breast, axilla and breast and axilla. METHODS: This retrospective study included 310 women with breast carcinoma who received NAC from 1/1/13 to 12/31/15 with follow-up until 8/31/16. The factors analyzed to predict pCR and cCR were menopausal status, Ki67, estrogen receptor, histologic grade, molecular subtype, tumor size, axilla status, and stage. RESULTS: The cCR/pCR rates were 53.2/16.5% (breast), 76.3/36.8% (axilla) and 50.6/13.9% (breast and axilla). Molecular subtype and HER2-positive were independent predictors to confirm pCR in women with cCR, mainly triple negative (TN) in breast (OR 22.81, 95% CI 7.13-72.96) and breast and axilla (OR 36.06, 95% CI 8.77-148.26), but not in axilla. Ki67 ≥50% expression was predictor of cCR in breast (OR 2.00, 95% CI 1.31-3.06) and breast and axilla (OR 1.67, 95% CI 1.10-1.45). CONCLUSION: TN subtype and HER2-positive were the main independent predictors of pCR in women who also had cCR to NAC in breast and breast and axilla, but none was predictor in axilla. The Ki67 ≥50% was the independent predictor of cCR in breast and breast and axilla.