Neoadjuvant chemotherapy for breast cancer: Pathologic response rates but not tumor size, has an independent prognostic impact on survival.

Aim: We investigated the pathologic complete response rates (pCR) and survival outcomes of early breast cancer patients who underwent neoadjuvant chemotherapy (NAC) over 14 years at a French comprehensive cancer center and reported pCR and survival outcomes by tumor subtypes and size. Methods: From January 2005 to December 2018, 1150 patients receiving NAC were identified. Correlations between cT stage, breast tumor response, axillary lymph node response, pCR, surgery, and outcomes were assessed. pCR was defined as (ypT0/ypTis) and (ypN0/pN0sn). Results: A pCR was reached in 31.7% (365/1150) of patients and was strongly associated with tumor subtypes, but not with tumor size (pretreatment cT category). Luminal‐B Her2‐negative and triple‐negative (TN) subtypes, cN1 status, older age, and no‐pCR had an independent negative prognostic value. Overall survival (OS), relapse‐free survival (RFS), and metastasis‐free survival (MFS) were not significantly different for cT0‐1 compared to cT2 stages. In Cox‐model adjusted on in‐breast pCR and pN status, ypN1 had a strong negative impact (OS, RFS, and MFS: HR = 3.153, 4.677, and 6.133, respectively), higher than no in‐breast pCR (HR = 2.369, 2.252, and 2.323). A negative impact of no pCR on OS was observed for cN0 patients and TN tumors (HR = 4.972) or HER2‐positive tumors (HR = 11.706), as well as in Luminal‐B Her2‐negative tumors on MFS (HR = 2.223) and for Luminal‐A on RFS (HR = 4.465) and MFS (HR = 4.185). Conclusion: Achievement of pCR, but not tumor size (pretreatment cT category), has an independent prognostic impact on survival. These results suggest potential NAC benefits in patients with small tumors (<2 cm), even in absence of clinically suspicious lymph nodes. Residual lymph node disease after NAC is the most powerful adverse prognostic factor. [ABSTRACT FROM AUTHOR]