Rationale/Objective: Neoadjuvant chemotherapy (NAC) is recommended for locally-advanced breast cancer (LABC) to improve resectability and provide in-vivo tumor response assessment. This study aimed to describe the clinical and pathologic tumor response of LABC patients after response-guided NAC. Methods: This is a retrospective cohort analysis of 128 LABC patients who underwent NAC using sequential doxorubicin/cyclophosphamide (AC) – docetaxel (T) regimen at the Philippine General Hospital Breast Care Center. Clinical and pathologic response rates were analyzed according to clinicopathologic variables including tumor intrinsic subtype. Results: Objective clinical response (complete and partial) was observed in 88% (111/128) of patients with 11% (14/128) achieving pathologic complete response (pCR). The hormone receptor-negative/ Her2-enriched (HR-/Her2+) subtype had the highest pCR rate (23.5%) followed by triple negative subtype (HR-/Her2-) at 19%. The hormone receptor-positive/Her2-positive (HR+/Her2+) subtype had the lowest pCR (4.7%). Two patients with initial poor response to AC but had good response upon shifting to T achieved pCR. Twelve patients (9.4%) had poor response to AC and T chemotherapy. Patients who were pre-menopausal (p=0.04), had ductal histology (p=0.03), with a HR-/Her2- (p=0.002) or HR+/Her2+ subtype (p=0.03) had good response to AC. Intrinsic subtype was not significantly associated with treatment response in those who received docetaxel. There was strong association between the pathologic and clinical responses (Spearman’s Rho score 0.69, p-value <0.0001). Conclusion Clinical and pathologic response to NAC was highly dependent on tumor subtype. Clinical response was predictive of pathologic response. Response-guided NAC allowed direct and early evaluation of tumor treatment response that allowed for treatment modifications.
Breast Neoplasms ; Neoadjuvant Therapy ; Drug Therapy