Changes in Pathological Complete Response Rates after Neoadjuvant Chemotherapy for Breast Carcinoma over Five Years

Historically, neoadjuvant chemotherapy (NACT) was extrapolated from adjuvant regimens. Dual HER2 blockade and the introduction of carboplatin for triple negative breast cancers (TNBC) emerged by December 2013 and have improved pathological complete response (pCR) rates. The objective of this study was to assess the pCR rates before and after the introduction of these new neoadjuvant regimens. Materials and Methods. Stage I-III breast cancer patients who received NACT were analyzed for rates of pCR by clinical characteristics (i.e., age, BMI, axillary lymphadenopathy, and histologic subtype), by time period (1 = 3/2010-11/2013, 2 = 12/2013-3/2015), and by type of chemotherapy (e.g., anthracycline/taxane only, carboplatin-containing, and HER2 blockade). Results. 113 patients received NACT. Overall pCR rate was 26.5 percent (n = 30). The pCR rate increased from 14% to 43.1% (p = 0.001) from time period 1 to time period 2 and were associated with HER2 positivity (p = 0.003), receiving treatment during time period 2 (p = 0.001) and using an anthracycline/taxane plus additional agent type of regimen (p = 0.004). Conclusions. Our study revealed a significant difference in rates of pCR over five years. Window of opportunity trials and other trials that utilize pCR analysis should be encouraged.