Neoadjuvant Chemotherapy for Breast Cancer: Evolution of Clinical Practice in a French Cancer Center Over 16 Years and Pathologic Response Rates According to Tumor Subtypes and Clinical Tumor Size: Retrospective Cohort Study

Abstract

We examined characteristics trends in early breast cancer patients receiving neoadjuvant chemotherapy (NAC) over a 16-year period. Our primary objective was to analyze variations in tumor stage and subtype over time. Secondary objectives included analyses of type of surgery and pathological response, from January 2005 to May 2021, 1623 patients receiving NAC were identified. Three periods were determined: 2005-2009 (P1), 2010-2014 (P2), 2015-2021 (P3). Correlations between periods and patient features with cT stage, pathological breast and axillary node response, pathological complete response (pCR), and type of surgery were assessed in univariate and multivariate analyses. We observed a significant increase in cT0-1 and N0 stages with periods (from 6.8% at P1 to 21.2% at P3, and from 43.2% at P1 to 55.9% at P3, respectively) and in the proportion of HER2+ and triple negative (TN) subtypes. In a multivariate analysis, a decrease of cT2-3-4 tumors during P3 was observed for HER2+ (OR:0.174; p=0.004) and TN tumors (OR:0.287; p=0.042). In-breast pCR and pCR were observed in 40.8% and 34.4% of all patients, respectively, with strong association with tumor subtypes, but not with tumor size in multivariate analysis (37.0% pCR for cT0-1 tumors, 36.4% for cT2 tumors, 29.1% for cT3 tumors (cT0-1 versus cT≥2; p=0.222)). pCR was negatively associated with cN1 stage (OR:1.499; p<0.001 for cN1 patients compared to cN0). We observed an increase in the proportion of small cT0-1 and N0 stages treated with NAC, especially in HER2+ and TN subtypes. No significant impact of tumor size on pCR rates was found.

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

“…Thus, it is unclear whether similar benefits may be found in smaller tumors. In a previous study, 15 we have shown that the pCR rate after NAC was neither higher nor significantly different for tumors <2 cm compared with tumors ≥2 cm, especially for HER2+ and TN subtypes for which adjuvant therapy can be offered to improve prognosis. An evaluation of OS and RFS comparing patients with these sizes of tumors and adjusted for other prognostic factors was warranted.…”

Negative Survival Impact of Occult Lymph Node Involvement in Small HER2-Positive Early Breast Cancer Treated by Up-Front Surgery

“…HER2-positive BCs larger than 2 cm or with clinical and/or ultrasound involvement of the axillary lymph nodes are currently treated with neoadjuvant chemotherapy [ 37 ], except where contraindicated by age, comorbidities, and, in particular, physiological age. However, as the rate of complete pathological response does not correlate with the initial clinical size of the tumor, neoadjuvant chemotherapy is increasingly proposed for tumors with no clinical axillary lymph node involvement of more than 15 mm, or even more than 10 mm [ 38 ]. This study aimed to determine, from a multicenter cohort, the prognostic value of axillary node invasion by ITC or micro-metastases in HER2-positive BCs treated by primary surgery for all patients, as well as for patients with pT1a-b cancer.…”

Triple-negative and Her2-positive breast cancer in women aged 70 and over: prognostic impact of age according to treatment

“…Hence, a significant proportion of older patients with TN and Her2-positive BC should receive neoadjuvant chemotherapy (+/-Trastuzumab): cN1 or cN0 usN1 with positive axillary lymph node and cN0 pT2. Meanwhile, neoadjuvant chemotherapy is discussed in patients with cN0 pT1c (mainly in 15-20 mm tumors) (26,27). After up-front surgery, lymph node-positive or lymph node-negative and > pT1b patients should receive adjuvant chemotherapy in TN phenotypes (28,29) and adjuvant chemotherapy and Trastuzumab in Her2-positive disease (28, 30).…”